mock exam 8 (anatomy , preventive, pediatric, periodontics and orthodontics (study mode)

Local resolution should be attempted for all complaints received by the practice— verbal or written. A clear complaints protocol should be in place, which includes the time frame for acknowledgement of receipt of complaint and the time frame for investigation. The GDC’s standards for dental professionals state practices require a clear and effective complaints procedure. It is good practice to acknowledge a complaint as soon as possible, and a full response should be given within 0 working days. If the investigation takes longer, then the patient should be updated at least every 0 days. Where local resolution fails, the NHS ombudsman or the Dental Complaints Service can be utilized for NHS and private treatment, respectively. These services may investigate the complaint and advise actions accordingly. It is unlikely that a well- handled complaint should require escalation to the GDC. However, issues of patient safety, illegal practice, or concerns regarding a registered dentist’s or dental care professional (DCp)’s conduct are more serious matters that are more likely to require GDC involvement. It may be advisable to contact your indemnity provider for advice before responding to complaints, as their guidance can help to resolve matters faster.

Gingival recession following orthodontic treatment is relatively common. Camouflage of the malocclusion can occasionally result in a tooth being positioned outside of the bony envelope, leading to dehiscence or fen estration. If there is associated inflammation in the tissue and the biotype is thin, then recession can result. Thicker biotypes with a greater bulk of connective tissue tend to result in less recession, as they are more robust. When aesthetics is not a major concern and the patient has no com plaints of sensitivity, root coverage surgery is not necessary unless the defect is progressing or excessive. If sensitivity is present, then desensitizing agents may be used to remedy this initially. The next consideration relates to the effect of the high frenal attachment. previous investigations demonstrated little evidence to suggest a frenal pull during muscular activity has any direct effect on gingival recession. However, the high attachment may inhibit effective plaque removal. Some clinicians also suggest there is a plunging effect which drives plaque into the gin gival sulcus or an effective gingival seal is prevented, either way perpetuating further local inflammation. Anecdotally, therefore, relieving the frenal attachment can help improve local plaque control and stabilize the situation. Alternatively, if the patient can maintain good plaque control, then surgery may not be warranted. Moreover, where there is little sulcal depth, apical displacement of the frenum during the procedure will help to create greater sulcal depth and facilitate any future root coverage procedures. Some clinicians may do this as a single- stage procedure, combined with root coverage, depending on the situation. It should be appreciated that treatment planning in these situations is contentious and very scenario- specific.

Localized gingivitis should be carefully examined to consider all possible aetiologies. In this case, recent crown placement is evidently the causative factor. poor crown margins are extremely common occurrences that should be rectified, if present. By definition, crown margins that are intra- sulcular have not invaded the junctional epithelium and, as such, have not encroached upon the supracrestal attached tissues. excess cement and poor crown margins were not identified upon clinical examination, and allergy to adhesive resin would be extremely rare. poor bulbous emergence profiles can hinder oral hygiene practices and promote plaque and biofilm development. Where insufficient reduction has been provided, the technician has to overbulk the restoration to create sufficient thickness of porcelain for aesthetics and strength. In this scenario, the opaque appearance is potentially suggestive of inadequate reduction. The veneering ceramic is thinner than required for optimal aesthetics, and the more opaque layer becomes visible. restorations with this design fault could represent a plaque- retentive factor, which would ultimately lead to localized gingivitis

Infrabony defects are usually classified by the number of remaining walls surrounding them (i.e. 0 to 3). The predictability of the regenerative outcomes is affected by wound stability and maintaining space for the repopulating cells. Defects that are self- contained are much more likely to maintain both the membrane and regenerative material in position, and therefore provide a stable clot during the healing period. In other words, a three- walled defect will support a membrane or regenerative material better than a one- walled defect. This is most relevant when unreinforced biodegradable membranes or gel formations of growth factor products are utilized, as they will displace more easily. Obviously, titanium- reinforced membranes may negate this problem, as they are self- supporting, but they do require a further surgical procedure to remove them. Furthermore, challenges can arise in producing primary closure with tented membranes, which is another factor that can affect the success of regenerative procedures.

The complement cascade is a general component of innate immunity. Activation of the complement cascade is pro- inflammatory. Activated complement recruits immune cells and assists in bacterial cell destruction. Complement also binds bacteria in a process known as agglutination, which assists in destruction of the pathogens. The membrane attack complex is formed during complement activation and is heavily involved in the destruction of pathogens. The classical, common, and alternative pathways have been identified. LpS (endo toxin), a component of bacterial cell walls, has been identified as a potent complement activator in periodontal disease. The classical pathway involves antigen– antibody complex formation, which activates C1 of the complement cascade. The alternative pathway is activated by LpS and bacterial proteases. Both pathways converge at C3 activation where the common pathway begins. IgG is an anti body produced by B cells, whilst IL- 1 is a group of immune- regulating cytokines.

The mucogingival junction is a soft tissue landmark where the attached

gingiva meets the alveolar mucosa. The attached gingiva is keratinized

tissue, which results in a distinctly lighter colour than the adjacent, highly

vascular alveolar mucosa.The keratinized attached gingiva serves a vital

protective function during mastication and tooth brushing. removal of

the entire attached gingiva is not advised for crown lengthening, and if an inadequate attached gingiva is present (i.e. <2– 3 mm), then apical repositioning of the flap is advised. The free gingival groove corresponds to the cemento– enamel junction of the tooth. At this point, the free gingiva meets the attached gingiva. The free gingival groove is present in <50% of patients and is often lost when periodontal tissues become inflamed. See Figure 4.2 which shows macroscopic periodontal landmarks.

Free gingival (FG) or connective tissue grafts involve complete detachment of the graft from its donor site to the recipient site. An FG graft involves removal of keratinized tissue, whilst a connective tissue graft is removal of the subepithelial connective tissue only. Adequate preparation of the recipient site is imperative for successful integration, as is careful handling of the graft during harvest and placement. The palate is the most common site for harvest of a soft tissue graft. Subepithelial connective tissue grafts are most commonly sourced from the palate, as the available volume is greater. The tuberosity can be used, but it often lacks the necessary width of connective tissue required in graft procedures. These flaps do not maintain their original blood supply and, as such, rely heavily upon the vascularity of the recipient site for survival. A key component of graft success is to ensure its immobility during the healing period and allow undisrupted angiogenesis. Alternatively, pedicle grafts are not detached and, as such, retain their blood supply. retention of blood supply is a significant advantage. However, these flaps can only be repositioned locally (e.g. rotational flap or coronal advancement flap) and sometimes lack sufficient volumes of connective or keratinized tissue.

Toothwear is an increasing problem within the adult population. Toothwear resulting in only  mm of remaining coronal tooth tissue is severe and has significant consequences in terms of treatment predict ability. Composite restorations placed at an increased occlusal vertical dimension (OVD) are now a relatively common treatment modality utilized in toothwear management. To facilitate restorations, crown length ening can be performed to apically reposition the gingivae and recontour the bone (osseous recontouring). An apically repositioned flap without osseous recontouring will likely result in gingival rebound with inad equate crown height gained. Gingivectomy alone is also likely to encroach upon the supracrestal attached tissues. reduction of the mandibular incisors may provide space for maxillary restorations, but no increase in bonding surface would be gained. Direct restorations to manage toothwear are commonly placed at an increased OVD, and the Dahl concept is utilized. Overdenture pro vision should not be overlooked as a potential management strategy; however, overdenture provision would not facilitate the direct restoration of teeth.

The scenario above describes a typical presentation of a patient with generalized aggressive periodontitis (Ap)— now classified as generalized stage III, grade C periodontitis. Ap is a relatively rare disease, associated with rapid attachment loss. plaque levels are often inconsistent with the severity of bone loss, and there are strong familial tendencies. patients are often young (<35 years) and otherwise fit and well.Antibiotics are important and often lifesaving medications. There are few indications for antibiotic use within dentistry, especially in the management of periodontal disease, but Ap is one indication.Localized Ap is associated with particularly virulent pathogens, e.g. Aggregatibacter actinomycetemcomitans (Aa), whereas serum antibodies to infective agents in generalized Ap are less robust. These pathogens have been shown to invade local gingival tissues, and this makes elimination with rSD alone challenging.The timing and use of antibiotics in Ap remain controversial. However, contemporary evidence shows a greater outcome with antibiotics provided immediately after the first round of rSD. prior to commencing any antimicrobial therapy, dentists should be confident in their diagnosis, with referral to a specialist advised. Complement inhibition therapy limits the effect of the complement system and has been shown to reduce the amount of inflammatory markers and minimize attachment loss and bone destruction in monkey models. There is no current evidence on their use in humans.photodynamic therapy is an antimicrobial treatment modality where a photosensitizer is administered to bacteria prior to application of a light source. The photosensitizer then breaks down upon activation to produce free radicals which damage the cell membrane. Clinical data do not show consistent long- term benefit overnon- surgical management alone.probiotic therapy involves taking a tablet containing primary colonizing bacteria that are more conducive to periodontal health, shifting the ecological environment. Again clinical results show minimal clinical significant difference over non- surgical treatment.

: Various systemic conditions are associated with rapid periodontal destruction. examples include: Chèdiak– Higashi syndrome, Down’s syndrome, ehlers– Danlos syndrome, hypophosphatasia, leucocyte adhesion deficiency, and papillon– Lefèvre syndrome. papillon– Lefèvre Syndrome is a rare autosomal recessive hereditary con dition, most common in the South Asian population. A genetic mutation results in the loss of function of a lysosomal enzyme found in neutrophils called cathepsin C; this has an important function in bacteria destruction. Other clinical findings include: palmar– plantar keratosis, arachnodactyly, recurrent skin infections, pes planus (flat feet), onychogryphosis (hyper trophic nails), and acro- osteolysis (resorption of distal phalanges). Management of these patients is difficult, and there is a high risk of tooth loss and edentulism. Furthermore, implants placed in these patients are high risk for peri- implantitis.

The three attachment structures of the periodontium to the tooth are as follows (coronal to apical):

1. The junctional epithelium
2. The connective tissue attachment
3. The periodontal ligament.

In health, the JE is, on average, 0.97 mm and the connective tissue attachment is 1.07mm; together, they comprise the supracrestal attached tissues (formally the ‘biological width’). During active periodontal dis ease, the Je becomes ulcerated and there is damage to the connective tissue attachment. As the process progresses, the periodontal pocket deepens and the Je and CT attachments migrate apically. Following successful non- surgical therapy, the epithelial cells migrate the quickest and are the first to colonize the root surface, starting at the apical portion of the pocket and migrating coronally. This leads to the formation of a long Je. The connective tissue repair then helps to stabilize this new attachment. In regenerative therapies, the aim is to restore the original periodontal architecture before disease and facilitate the formation of new cementum, pDL, and bone. Healing following successful non- surgical periodontal therapy is therefore reparative whereby a long Je develops.

plaque is the primary cause of periodontitis. If the patient is unable or unwilling to maintain low plaque levels, another round of rSD is unlikely to provide any long- term benefit. patient education and involvement is fundamental to successful management of periodontal disease. This discussion is dynamic and must adapt to each patient’s situation. It is important to emphasize that professional treatment is an adjunct to excellent home care. Further discussion of the aetiology, management, and progression of periodontal disease, along with further oral hygiene instruction, should take precedence over further treatment. referral for periodontal surgery is inappropriate, as periodontal surgery is not suitable for generalized periodontitis in patients with poor compliance. Antibiotics are not routinely used to treat periodontitis, unless disease is rapidly progressing and suggestive of grade C (aggressive) periodontitis. Specialist periodontists are unable to provide any additional treatment until suitable levels of plaque control are attained.

Necrotizing periodontal diseases involve bacterial invasion of the periodontium, leading to necrosis and tissue damage. The condition is usually very painful and associated with distinct malodour. Amongst others, bacteria thought to be associated with this disease are Prevotella intermedia, Fusobacterium spp., and Treponema spp. patients may also be immunocompromised. Therefore, risk factors, such as smoking, stress, malnutrition, poorly controlled diabetes, steroid use, and other medical conditions which may compromise the immune system, should be noted. Management of this condition is through a combination of antibiotics and localized mechanical debridement of the biofilm (local anaesthesia is often required in order to do this).

: Diagnosing drug- induced gingival overgrowth (DIGO) requires a thorough history and examination. Suboptimal oral hygiene could precipitate gingival swelling in the form of dental biofilm- induced gingivitis. However, the appearance of gingival overgrowth is generally distinct from that of dental biofilm- induced gingival swelling. Careful consideration of the patient’s medications is prudent. Anticonvulsants (phenytoin), immunosuppressants (ciclosporin), and calcium channel blockers (nifedipine) have all been implicated in the development of DIGO. All the drugs listed above could be used in the management of this patient’s medical conditions. Of the drugs listed, amlodipine, a calcium channel blocker, is frequently associated with DIGO. Whilst nifedipine may have been more widely reported in the literature regarding the development of DIGO, amlodipine is an alternative calcium channel blocker more regularly prescribed and also linked with DIGO. Good knowledge of drug classifications and drug names is important in determining the correct answer in this scenario.

The scenario describes a young male patient with what was traditionally known as localized aggressive periodontitis but would now be classified as localized, grade C periodontitis (the stage would reflect the amount of destruction at the specific time point). Aggressive periodontal dis ease described a group of diseases in which there is rapidly progressing destruction of the periodontal attachment. It is classified as either local ized, generalized, or molar– incisor, depending on its distribution. In the majority of cases, patients tend to be younger in age with good plaque control. There is also a propensity for familial aggregation, and patients display a non- contributory medical history. Whilst multiple ‘red- complex’ pathogens have been implicated in periodontitis, Aggregatibacter actinomycetemcomitans (Aa), formerly Actinobacillus actinomycetemcomitans, has been identified as a key pathogen in localized aggressive periodontal disease (now more cor rectly approximated to molar– incisor, stage III, grade C periodontitis), with patients demonstrating serum antibodies against the causative agent. This bacterium possesses numerous virulence factors, enzymes, and endotoxins which upregulate the connective tissue inflammatory response, increase connective tissue destruction, and inhibit poly morphonuclear leucocytes function. Furthermore, this bacterium may also invade epithelial cells of the periodontal pocket, increasing its resist ance to root surface debridement

The basic periodontal examination is a widely used screening tool to assess for the presence of periodontal disease. It is conducted with a ball- ended probe that has black bands on it (WHO 621 probe) at 3.5– 5.5 mm and 8.5– 11.5 mm. When conducting the assessment, the mouth is split into sextants and every tooth (apart from the third molars) is examined; the worst score for each sextant is recorded. The score then gives an indication of what treatment is required. Table 4. describes the scoring system. The addition of a star to a sextant score indicates there is furcation involvement. Historically, the star was a standalone score for a sextant indicating either furcation involvement or attachment loss of >7 mm; however, this was changed in 2011.

Until recently, classifications of periodontal disease were based upon

the work of Armitage and colleagues at the International Workshop for

Classification of periodontal Diseases and Conditions in 1999. A new

classification system was released in summer 2018, based upon updated

understanding of periodontal biology, which also allows for incorporation of individual patient factors. It is a more pragmatic multidimensional staging system that not only facilitates future adaption to emerging

evidence, but also permits personalized diagnosis that is crucial to con

structing a comprehensive care plan. One of the big changes is ‘aggressive’ disease and ‘chronic’ disease are no longer distinct entities and have been incorporated into an overall umbrella term of ‘periodontitis’, which is subsequently modified by the clinical findings for that individual patient.

periodontal disease is now classified by:*

1. The severity and complexity:

Stage I: initial periodontitis

Stage II: moderate periodontitis

Stage III: severe periodontitis with potential for additional tooth loss

Stage IV: severe periodontitis with potential for loss of dentition

2. The extent and distribution:

Generalized: >30% of dentition affected

Localized: <30% of dentition affected

Molar– incisor distribution: affecting incisor and molar teeth

3. The risk of progression or anticipated treatment response:

Grade A: slow rate of progression

Grade B: moderate rate of progression

Grade C: rapid rate of progression.

periodontal disease is extremely prevalent in the population. Traditionally, the disease process was classified into four stages: initial, early, established, and advanced— although ultimately, it is a continuous spectrum. In the first three stages, signs of inflammation develop and the immune response establishes. Vasodilatation occurs, bringing with it various cytokines and leucocytes. As the disease becomes more established, there is a shift from the innate immune response to the adaptive immune response, with T and B cells beginning to predominate. The next stage is the advanced stage of the disease (periodontitis). In this stage, there is a dense inflammatory infiltrate, with large numbers of inflammatory mediators present. The mechanism of tissue destruction is a complex combination of direct bacterial action and indirectly as a result of the host response. Not all cases progress from gingivitis to periodontitis, but it is known that the host response plays a significant part in the overall clinical picture. Around 0– 5% of the population will be hypersensitive and suffer from severe disease, and about 0% of the population will be innately resistant to the disease process. recession and pocket depth measurements are combined to calculate clinical attachment loss.

: Gracey curettes are site- specific hand scalers used for subgingival debridement. The lower terminal shank should be inserted parallel to the long axis of the tooth. The working tip is designed with a single lower cutting edge to improve adaptation of the curette to the root surface and the base of the pocket. If inserted correctly, this produces an optimal angle of 70° between the tooth surface and the working tip. Absence of a second cutting surface is designed to reduce trauma to the periodontal tissues when scaling.

: research by Lang et al. in the 980s and 990s highlighted the link between absence of bleeding on probing (BOp) and periodontal sta bility. recession and a reduction in probing pocket depths are likely to represent successful treatment outcomes. However, these factors alone do not indicate periodontal stability, as further periodontal destruction could occur concomitantly. plaque retentive factors are likely to encourage biofilm formation and aggravation of periodontal tissues. These should be addressed as part of the overall periodontal management. plaque accumulation is a fundamental component in periodontitis. plaque indices, such as the O’Leary plaque index, are useful tools in the assessment and management of caries and periodontitis. Whilst they are useful in assessing patient compliance and prognosis, a low plaque score does not indicate periodontal health, as plaque accumulation will inevit ably lead to gingival inflammation, which, depending on host response, may progress to periodontitis.

Study models are an important part of case planning and assessment in orthodontics. They are part of a patient’s clinical records and, as such, should be kept for a minimum of  years or until the patient is 25 years old (whichever is longer). In this scenario, as the patient was  years old at the time of the impressions, they should be stored until the age of 25 because this is longer than the standard  years for adults. As they have already been stored for 4 years, they need to be kept for a further 0 years. This also applies to clinical notes, clinical photographs, and radiographs, which all form part of a patient’s medical records.

With the digital revolution in dentistry, scanning and storing models electronically can save vast amounts of space, but it is important to ensure adequate security systems are in place and the data are regularly backed up. The guidelines below illustrate time to keep records.

In a growing patient, an upper removable appliance with a flat anterior bite plane allows eruption of the posterior teeth and reduction of a deep overbite. The resultant reduction in vertical overlap of the teeth (overbite) will allow a lower fixed appliance to be placed simultaneously, without the lower brackets being in traumatic occlusion.

A twin block is a type of functional appliance. These guide the forces of muscle function, tooth eruption, and growth to encourage correction of a malocclusion. Commonly, twin blocks are used in growing patients to correct Class II malocclusions with an increased overjet. A twin block will correct a deep overbite by differential eruption of the posterior teeth. As this patient is young, it is possible to utilize his growth in the management of his malocclusion. The timing of twin block appliances is important, and preferably they should be used just before the ado lescent growth spurt begins. However, they require adequate retention such as using Adam’s clasps, labial bows, and ball hooks. Correction of the malocclusion has been attributed to roughly 30% of skeletal and 70% of dento- alveolar change. Orthognathic surgery is reserved for when facial growth is com plete but the skeletal pattern is too severe to consider orthodontic camouflage alone.

Supernumerary teeth occur in 2% of the population in the permanent dentition and are more common in males. Supernumerary teeth can be described according to their morphology or position in the arch. Conical supernumerary teeth are the most common form, and when a con ical supernumerary tooth is located in the midline, this is known as a mesiodens. Conical supernumerary teeth can cause displacement or failure of erup tion of a maxillary central incisor, or crowding. In some cases, super numerary teeth have no effect on adjacent teeth. Typically, they require removal to facilitate alignment. Complex and compound odontomes are disorganized masses of min eralized tissue that can impede eruption of teeth.

The angle ANB represents the relationship of the maxilla and the mandible to the anterior cranial base and is obtained by subtracting the angle formed by the sella turcica, nasion, and B point (SNB) from the sella turcica, nasion, and A point (SNA).

ANB = SNA –  SNB

The average value is 3° ± 2°, indicating a Class I skeletal relationship. An increased ANB value is indicative of a Class II skeletal relationship, and a decreased ANB is indicative of a Class III skeletal relationship. Broad classification is as follows:

• ANB <2°: Class III
• 2° ≤ ANB ≤ 4°: Class I
• ANB > 4°: Class II.

parallax is a technique used to identify the position of an unerupted tooth relative to a reference point such as an adjacent tooth. Two radio graphs must be taken, with a change in the position of the X- ray tube between the two radiographs. The object farthest away from the X- ray beam will move in the same direction as the tube shift. Two periapical radiographs can be used for horizontal parallax, and an OpT and a USO for vertical parallax. In this scenario, an OpT is also required to assess the developing dentition.

The ‘SLOB’ rule can be used as a memory aid for this (same lingual, opposite buccal). When using the parallax technique, if a tooth moves in the same direction as the change in direction of the X- ray beam, then that tooth is lingually/ palatally positioned. CBCT is a very useful contemporary tool for assessing impacted teeth. However, due to the higher dose of radiation, it is not a first- line imaging technique and is reserved for cases where resorption of the adja cent teeth is suspected or further information is required for surgical exposure of the canine.

The definitions for Classes , II (1), II (2), and III should be known, in order to be able to do an orthodontic assessment in practice and make appropriate referrals.

Class I— the lower incisor edges lie immediately below the cingulum plateau of the upper incisors.

Class II, division — the lower incisor edges lie posterior to the cingulum plateau of the upper incisors and the upper central incisors are proclined or of average inclination with an increased overjet.

Class II, division 2— the lower incisor edges lie posterior to the cin gulum plateau of the upper incisors and the upper central incisors are retroclined. The overjet is usually minimal or may be increased.

Class III— the lower incisor edges lie anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed.

Class II is always classified with a respective subdivision.

In this scenario, the lower incisors occlude posterior to the cingulum plateau, indicating a Class II relationship, and the upper incisors are retroclined.

Bodily movement requires 50– 20 g force, similar to the force required to torque teeth into position, which is 50– 100 g. rotational movement and extrusion require a force of 35– 60 g. Tipping movements require 25– 60 g. Bodily movement requires the highest force, as a greater area of the periodontal ligament is involved, so the force is dissipated over a greater area, and therefore, more force needs to be applied in order for optimal force levels to be obtained.

: The ideal ages for the use of functional appliances to achieve the de sired jaw growth vectors is 0– 2 years for girls, and 2– 4 years for boys. Studies have shown that an earlier treatment start with a twin block prolongs treatment time for patients and can result in losing patient compliance with lengthened treatment. Following a twin block (approximately 9 months if worn well), fixed appliances are provided, which is a further 8– 24 months of treatment. Cases where a twin block may be fitted early include occasions when a child is being bul lied about their malocclusion or when a child is at increased risk of trauma.

Orthodontists may differ in the retention regime prescribed; however, in the absence of clear instructions, vacuum- formed retainers should be worn every night (2 hours). There is a high risk of relapse if the patient does not consistently wear them. There is a risk of caries and damage to the enamel if food and drinks are consumed whilst wearing the retainers. Only water can be consumed safely. The patient should return to their orthodontist to seek clarification of their retention regime if they are unsure.

A removable appliance typically comprises four parts: one or more ac tive component, retention, anchorage, and a base plate. The active com ponent exerts the force required for the desired movement and can be a spring, an elastic, or a screw, or a combination of any of these com ponents. For arch expansion, a midline expansion screw is commonly used. There are various types of springs and screws that can be used, depending on the tooth movement required.

• An acrylic base plate provides the framework of the appliance to which all other components attach and provide anchorage.
• Adam clasps are a non- active component which provide retention by engaging undercuts, generally on the posterior teeth.
• An alternative retentive component is a southend clasp on the anterior teeth.

● A posterior bite plane allows some disclusion to aid crossbite correction

Fixed appliances can offer a wider range of tooth movements in com parison to removable appliances. Greater control over tooth movement can be achieved, as brackets not only provide vertical or tilting move ments on the tooth surface, but also a force couple can be generated by the interaction between the bracket and the archwire. rotational and apical movements are also possible. removable appliances are capable of the following tooth movements:

1. Tipping
2. Movement of a block of teeth
3. Influencing eruption of opposing teeth, i.e. flat anterior bite plane, buccal capping.

Overbite is described as the vertical overlap of the lower incisors by the upper incisors, along with a description of the contact that the lower incisor edge makes with the upper incisors or palate. The normal ver tical overlap is described as the upper incisor teeth covering one- third to one- half of the lower incisor crown height. Less than this is described as reduced, and greater than this is described as increased. An overbite is complete if the edge of the lower incisors make contact with the upper incisors or palatal mucosa, and incomplete if the edge of the lower in cisors do not make contact with the tooth surface or palatal mucosa. An increased overbite is more commonly associated with Class II division 2 cases where the upper central incisors are retroclined. An increased overbite does not necessarily require treatment, unless it is causing trauma to the palatal mucosa.

Decalcification occurs when cariogenic plaque is present with a high- sugar diet. A fixed appliance predisposes to plaque accumulation, as cleaning around the fixed appliance can be difficult. Demineralization of the enamel can occur if patients do not follow dietary advice and do not brush their fixed appliances adequately, leaving a white outline around the brackets. Some degree of tooth mobility during treatment is normal. Other common risks discussed include relapse, root resorption and gingival recession. rarely, pulpal necrosis might occur if rapid and excessive force is applied to the teeth that are already compromised.

The dental health component of the IOTN was developed from an index used by the Dental Health Board in Sweden to reflect these occlusal traits. Grade 5 indicates a very great need for treatment:

• 5a— increased overjet greater than 9 mm
• 5h— extensive hypodontia with restorative implications (> tooth missing in any quadrant), requiring pre- restorative orthodontics
• 5i— impeded eruption of teeth (except third molars) due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause
• 5m— reverse overjet greater than 3.5 mm, with reported masticatory and speech difficulties
• 5p— defects of cleft lip and palate and other craniofacial anomalies
• 5s— submerged deciduous teeth.

The clinical scenario describes a 9- year- old child with delayed eruption of a permanent central incisor. With the exception of the midline super numerary tooth impeding eruption, none of the other options would score grade 5. Moreover, this patient is very young and not all of her permanent dentition will have erupted. Therefore, an accurate assess ment of her IOTN is difficult, but a midline supernumerary tooth would be picked up at around this time frame. Delayed eruption of a permanent maxillary incisor tooth can be con sidered in the following circumstances:

• eruption of the contralateral incisor occurred >6 months previously
• The maxillary incisors remain unerupted > year after the eruption of mandibular incisors
• There is a significant deviation from the normal eruption sequence, i.e. lateral incisors erupting prior to the central incisor.

The index of orthodontic treatment need (IOTN) comprises a dental health component and an aesthetic component. The acronym MOCDO (Missing teeth; Overjet; Crossbite; Displacement of contact points; Overbite) can be used to help prioritize the single worst feature of a malocclusion, in order to score the dental health component. The order of the acronym is hierarchical. A score of 4d indicates severe displacement of teeth of >4 mm.

• 3a— increased overjet 3.6– 6mm with incompetent lips
• 3d— displacement of teeth 2.– 4mm
• 3f— increased and complete overbite without gingival trauma
• 4a— increased overjet 6.– 9mm.

The scenario describes a potential case of dental neglect. At 7 years of age, the child will rely on parents to attend appointments and, as such, the term ‘was not brought’ is preferred over ‘did not attend’. As a junior clinician, the foundation trainer should be the first port of call to discuss the case. It is more than likely that the foundation trainer will have experience in handling such cases, with pragmatic advice to assist in handling the issue. It is important to adhere to your local safeguarding policy and any guid ance provided by your local safeguarding children board. However, re peated failure to comply with reasonable appointment requests would be a cause for concern, and your practice or local safeguarding nurse would be an appropriate second step. This may require follow- up with the patient’s GMp or local Social Services Department, as the family may be known to social services and may already have a designated support worker assisting the family.

GA should be reserved as a last resort; however, in this case, the main concerns are the patient’s medical status and level of anxiety; for this reason, a GA referral would be appropriate. poorly controlled diabetes would warrant extra precaution during the GA procedure; for this reason, it is often best to keep the patient in overnight. However, this decision is made at the discretion of the treating anaesthetist, and in some cases, this may be managed as day- case GA, providing inpatient facilities are available, should they be required. Good cooperation is needed from patients during inhalation sedation, as the patient is conscious during the procedure. This may be difficult for a patient of such young age. performing extractions using local anaesthesia in multiple quadrants in anxious patients may be difficult, as they may not wish to return after the first appointment.

AI describes a number of genetically controlled conditions that affect the structure of enamel. The conditions are hereditary but can occur following spontaneous genetic mutations and can present in numerous different forms. enamel derived from epithelial tissue in the developing tooth germ is produced by ameloblasts. The timing of the defect with regard to enamel development is fundamental to the type of enamel formed, and ultimately the defect observed. The process is intimately linked with genetics and can be classified based on the mode of inherit ance. However, the type of defect is often used to classify the condition.

• Hypoplastic— enamel is often thin or translucent. radiographically, normal enamel– dentine contrast is observed.
• Hypocalcified— this results from inappropriate calcification and, as such, the enamel is of normal thickness but is weak or chalky. This structural change results in enamel that appears more radiolucent than the underlying dentine.
• Hypomaturation— this results from inappropriate resorption of the enamel matrix. The enamel is stronger, by comparison to hypocalcified AI, but is generally softer than normal and is prone to wear. Mottling can occur, and similar enamel– dentine radiodensity can be observed.

An unrestorable molar tooth will require extraction. Therefore, root canal treatment is not appropriate. When extracting FpMs, there is a risk of undesirable tooth movement of adjacent teeth, which may provide unfavourable over- eruption or changes to tooth alignment. This should be taken into account when planning treatment for the patient. Due to the risks involved with a general anaesthetic, treatment plans are fre quently more radical in order to try and prevent repeat operations. It is suggested that, with FpMs, when a lower molar is removed, removal of the opposing upper FpM should be given close consideration to prevent over- eruption (i.e. a compensating extraction). Where a local anaes thetic can be used, these extractions are hard to justify and removal is indicated only if there is unfavourable movement at review. Balancing extractions (removal of the contralateral tooth) is unwarranted, as there is no evidence to suggest removal of FpMs affects the midline. In the case of severe crowding or complex malocclusions, orthodontic input is suggested. The evidence supporting this is fairly weak, and each case should be assessed individually.

: This developmental defect is caused by invagination of the enamel epi thelium into the dental papilla during tooth formation. It is most commonly associated with the upper lateral incisors and sometimes the premolars. In this instance, the patient is young and has no symptoms, so a more conservative approach would be suitable. Good- quality fis sure sealants would reduce the chances of developing caries without sacrificing tooth tissue. Flowable composite may be considered a suitable alternative. However, fissure sealants are considered a more suitable first- line management strategy (many of which are resin- based anyway). Depending on severity, teeth with dens invaginatus are highly susceptible to caries, so simple oral hygiene instructions are unlikely to prevent decay. As the patient is asymptomatic, with positive sensibility tests and no evidence of active caries, more complex restorative treatment is not necessary at this stage. Teeth with dens invaginatus can be challenging to perform root canal treatment on, with CBCT frequently used to diag nose and help plan treatment.

At the age of 8 years, the Ur would be expected to have incomplete root development, as completion occurs typically 2– 3 years after erup tion. Although the coronal pulp has been contaminated, inflammation is usually fairly localized due to the cellular structure of the pulp. If the inflamed/ infected pulp tissue is removed, there is potential for healing to occur and pulp vitality to be retained. The resulting benefits include con tinued root development and maintenance of normal repair, defence, and sensory functions. The clinical technique for this is called a pulpotomy (complete or partial). The tooth should be kept under review, as in the long term, there is a risk of losing vitality. Where the apex is immature, the potential for healing is considered to be better. A direct pulp cap could be attempted if pulp exposure is not so severe (<1mm and <24 hours). extraction would not be an ideal first- line treatment in this case as the tooth is still restorable, and root canal treatment is inappropriate as the tooth is still vital. Apexification is useful when a tooth with incomplete root formation has lost vitality. Non- setting calcium hydroxide can be used to induce a calcific barrier at the apex before root canal treatment can be performed, but more commonly a bioceramic barrier technique is now employed.

Modelling is a branch of observational psychology that involves a behav iour being learnt through imitation. Specifically to dentistry, the young or inexperienced child observes a non- fearful child, or ‘model’, having a positive experience at the dentist. This approach is thought to work best if the patient can observe a ‘live’ model with whom they can closely relate, i.e. they are a relative or friend of similar age. In reality, the model is often an older sibling, parent, or family member. Behaviour shaping utilizes selective reinforcement, in which positive reinforcement is provided for behaviours that are closer to the desired behaviour, e.g. praising a child for sitting nicely in the chair, even though they will not open their mouth. enhanced control is designed to empower the child, so they feel in control of the situation. A stop signal or a countdown are useful examples of this. Systematic desensitization is one approach to achieving a desired goal in phobic patients. A hierarchy of steps are outlined, with each step getting progressively closer to the ultimate de sired goal. positive reinforcement is a branch of operant conditioning whereby a behaviour is strengthened, based on its association with a positive stimulus.

: In this case, the Ur is considered to be moderately intruded and importantly, root development is incomplete. Severity of intrusion:

• Mild 6 mm.
• Moderate 3-6mm
• Severe >6mm

Initial management for permanent incisors that have incomplete root development is to allow for passive repositioning for 2– 3 weeks. However, each clinical situation differs and some severe intrusions can be managed surgically. Active repositioning, including surgical and orthodontic repositioning, should be considered if no movement is evident within the first 2– 3 weeks or if passive eruption ceases and the tooth remains infraoccluded. Teeth with complete root development that are mildly intruded can be monitored for passive repositioning for 2– 3 weeks prior to active repositioning. Moderate and severe intrusions are best managed with either orthodontic or surgical repositioning and may be best referred for specialist care. Appropriate special investigations and trauma charts should be carried out to monitor the vitality of the intruded tooth and its adjacent teeth. It is likely that root canal treatment will be required, especially in teeth with complete root development, and regular radiographic analysis should occur to confirm no inflammatory resorptive changes.

Minimal occlusal caries with evidence of dentine involvement requires exploration and removal. preventive resin restoration enables caries to be identified and removed, whilst remaining minimally invasive. Furthermore, fissure sealing of the remaining fissure pattern will protect the tooth from further occlusal caries in the pits and fissures. Amalgam is a suitable restorative material, but it is more destructive due to cavity design requirements for retention and the need for a minimum thickness of approximately 2 mm. Implementation of the Minamata Convention recommendations is also decreasing amalgam usage. From  July 208, in england, regulations state that amalgam should not be used in children under 5 years of age and pregnant or breastfeeding women (unless deemed strictly necessary by the clinician). A conventional composite restoration may be required if the caries extends over a significant pro portion of the occlusal surface or through the marginal ridge. Dentists using truly minimally invasive procedures have presented evidence for sealing caries with resin fissure sealants alone. Theoretically, sealing the carious lesion blocks substrate from reaching the bacteria. However, caution is required during placement of the sealant, with careful long- term maintenance. Fissure sealants alone in irregular attendees would not be advised.

Treatment depends upon multiple factors, including the severity and rate of infraocclusion and the patient’s age. However, an orthodontic assessment is nearly always indicated to enable the correct long- term treatment plan to be decided, particularly when there is concomitant malocclusion. early diagnosis of infraoccluded teeth can help to reduce potential complications. Delayed treatment can result in: tipping of adjacent teeth, loss of arch space, over- eruption of opposing teeth, insufficient development of alveolar width or height, increased risk of developing caries, and localized periodontal attachment loss. As a per manent successor is not present, orthodontics could help to close the space, without the need for restorative treatment, or to maintain the space to facilitate restorative treatment in the future. reassurance and monitoring of an infraoccluded tooth are only advised in the short term if the tooth is not ankylosed, the successor is present, the tooth is not having a detrimental effect on the patient’s oral health, and the degree of infraocclusion is slight. This is usually more relevant in late- presenting adult patients. Composite build- ups and indirect onlays can be used in the medium term to maintain occlusal stability in cases of slight or mod erate infraocclusion. In this scenario, extraction will be likely due to the severity and the patient’s age, but an orthodontic opinion is needed first. Definitive restoration of the resulting space would typically be delayed until dento- alveolar development is complete, or it may not be necessary.

When trauma causes a tooth to become mobile, splinting can pro vide stability to allow periodontal healing and comfort for the patient. Splinting for too long can result in the tooth becoming ankylosed, and not splinting for long enough may result in less favourable healing out comes. Generally, the type of healing is classified as: calcific healing (dentine and cementum), fibrous healing (connective tissue), osseous healing (bone and connective tissue), and non- healing. The chances of calcific healing are likely improved with good apposition of the fractured segments— potentially more so than the length of time for which the tooth is splinted. patient advice should include a soft diet for a week, good oral hygiene, and short- term use of chlorhexidine mouthwash for optimal prognosis. Follow- ups are recommended at 4 weeks, 8 weeks, 4 months, 6 months,  year, and 5 years.

This child has a high caries rate and should be managed accordingly. An evidence- based toolkit has been devised by the United Kingdom’s Department of Health to assist in the management of oral health in children and adults. The third edition of this toolkit was released in 2014. Children aged 7 years and older who are causing concern should be placed on a 3- month recall. They should have fluoride varnish applied twice or more times a year, and all permanent molars fissure- sealed using a resin sealant, ideally within the first year post- eruption. A fluoride mouth rinse may also be considered from the age of 8 years. Diet advice and oral hygiene instructions are fundamental in managing these cases and should be reinforced at every opportunity. A significant proportion of this educa tion and advice needs to be directed towards the child’s parents or carers.

Unplanned early or late loss of a lower first molar can create numerous occlusal problems and exacerbate malocclusions. The timing of the extraction is therefore very important. The best predictor for this is when there is radiographic evidence showing calcification of dentine at the root bifurcation of the lower second molar. This is thought to occur between 8 and 0 years. Analysis of the developing dentition and ortho dontic consultation should be sought, if possible. However, removal of pain and infection should take priority, if present. early loss of a lower first permanent molar is associated with:

• Distal drifting, tipping, and rotation of the second premolar
• potential for premolar spacing. Late loss of a lower first permanent molar is associated with:
• Mesial tipping and mesio- lingual rotation of the lower second molar. This results in poor occlusal contacts and buccal segment spacing

● The second premolar can drift distally. Orthodontic consultation is required, as skeletal classification and crowding can impact upon the designated treatment plan

pMCs or stainless steel crowns (SSCs) are the restoration of choice in teeth that have been pulp- treated, either with pulpotomy or pulpectomy. Asymptomatic carious primary molars with marginal wall breakdown or caries involving two surfaces are also recommended for restoration with a pMC. A systematic review of five randomized controlled trials concluded that teeth restored with pMCs were less likely to develop problems such as pain and abscess formation, as well as being less uncomfortable to the patients during treatment. plastic restorations with amalgam, composite, compomer, and GIC generally record a poorer performance by comparison to pMCs, which show lower failure rates in many studies.

It is unusual for anybody to hurt themselves behind the ears or the neck. Accidental injuries usually occur on areas of the body that are exposed (hands) or areas which protrude (chin, nose). Therefore, trips and falls can easily traumatize a child’s chin, hands, or knees. Other suspicious injuries include torn frena in non- ambulatory children, bruises of different ages (i.e. various shades and colours), and bruises around the thighs and buttocks. Assessment of the child’s general appearance, including cleanliness, and their social interactions with family and the dental team will provide further information regarding the likelihood of neglect or an NAI. Discussing the injuries with the child’s parents or the child themselves may elicit important information regarding the mechanism of injury, which may corroborate the clinical findings. escalation and discussion with a more senior clinician, a practice safe guarding lead, or a local safeguarding officer/ nurse would be appropriate as a first- line measure. It is not advisable to manage these situations on your own or without additional support. You should always be aware of your local child protection guidelines.

The simplified Bpe uses a WHO 62 probe to examine the index teeth of children aged 7– 7. The index teeth are all permanent first molars and the upper right and lower left permanent central incisors. It has been recommended that between the ages of 7 and , Bpe scores— 0, , and 2— are used to assess gingivae for bleeding, calculus, and plaque reten tive factors. prior to 2 years of age, periodontal false pocketing can be evident, particularly around partially erupted teeth. From 2 to 7 years of age, the full range of Bpe scores— 0, , 2, 3, 4, and *— should be used on index teeth. Assessment of all teeth is considered excessive, as true periodontal disease would be unlikely to present without involving the index teeth described above. Just as in adult patients, further investigations would be required if pocketing is identified, which would include radiographs and more detailed periodontal charting. Specialist referral may be required in these cases.

Dental caries is a dynamic process. For demineralization to occur, the following four factors must be present.

• Substrate (fermentable carbohydrate)
• Bacteria
• Time
• Host (tooth).

All of the options above may be involved in caries prevention. Clearly, in this scenario, no amount of intervention or preventative advice will reduce the caries risk, unless the frequency of sugar intake is reduced. each time food or drink (with sugars in) is consumed, substrate will be available to bacteria in dental plaque. The result is a drop in acidity of the local environment at the tooth surface, leading to demineralization. eventually, saliva buffers the acid formed by fermented carbohydrates and tips the equilibrium in favour of remineralization. The more frequent the intake of sugar, the greater the length of time that demineralization will occur throughout the day. Therefore, in this scenario, it is important to reduce the intake of sugar. Fluoride contained within oral saliva is especially effective at remineralizing enamel when it comes in contact with the enamel– plaque interface. Constant supply of low- level fluoride in liquid form (i.e. topical fluoride) is most effective at preventing caries. Brushing removes plaque and thus helps prevent further demineralization, thus tipping the dynamic process in favour of remineraliza tion. Systemic fluoride is less effective in caries prevention than topical fluoride, and it does not remineralize softened enamel. Systemic fluoride used during tooth formation can help with caries prevention by strengthening the tooth structure and forming shallower fissures, which are less susceptible to caries. Chewing gum will stimulate saliva after consumption of food or drink.

The Children Act 2004 sets out who has parental responsibility for a child. The information provided in this scenario means that no date of birth is actually required to interpret parental responsibility. Biological fathers who are named on the birth certificate for births registered after  December 2003 (in england) or who have subsequently married the mother would be able to give legal consent. Therefore, in this scenario, the father can provide consent for treatment. In addition to this, fathers holding a court order granting them parental responsibility overrides any issues relating to birth certificates and marital status. If a mother were to choose to give her child up for adoption, she would also surrender parental responsibility to the adopting parents. In situations where a patient under the age of 6 presents for treatment, a clinician can use his or her professional judgement to establish whether the patient understands the nature of treatment, along with its benefits and limitations, and whether they can compare alternative treatments to come to a decision. This is called Gillick competence. It is unlikely that a child of this age can truly understand and weigh up the information regarding their dental treatment. Clinicians are advised to exercise caution when determining if a patient is Gillick- competent and, if possible, to delay treatment until an adult with parental responsibility is available.

The history and examination describe a lateral luxation injury. These teeth are often non- mobile due to impaction of the root into the alveolar bone and can be associated with vertical displacement. Dental trauma injuries are common between  and 4 years of age. preservation of the integrity of the permanent successor is a fundamental concept when managing primary dental trauma. Luxation with labial crown displacement carries a high risk of damage to the permanent tooth, as the root is displaced towards the developing tooth germ of the permanent successor, and consequently, they are best managed with extraction. Severity of damage to the permanent tooth has been linked with the age of the child at injury. radiographs are likely to show the tooth is elongated and would reaffirm the need for extraction. Mild luxation injuries may be monitored when damage to the permanent successor is not suspected. Orthodontic re positioning is not appropriate for this scenario, but referral to a specialist may be indicated where compliance is challenging and general anaesthesia is necessary, which may frequently be the case within this age bracket

The child is only 4 years old and will be in the primary dentition. primary teeth must never be re- implanted, as the apex of the primary tooth may be pushed into the developing permanent tooth germ, causing damage. Losing consciousness after trauma may be an indicator of an underlying brain injury, so it is important to have the patient examined immediately by a medical professional. Other indicators of neurological damage include vomiting, memory loss, confusion, and headaches. Checking for neurological damage would take priority over the patient’s oral health in most situations. reassurance only is incorrect in this scenario. Trauma must always be followed up with a dentist to examine for oral injuries and to allow clinical and radiographic assessment, as symptoms or pathology may have a delayed presentation.

It helps to know the eruption dates of all teeth. Knowing which teeth should be present at any given age will help you to identify the teeth when charting and will alert you to abnormal eruption patterns which may have an underlying cause. In this particular scenario, the mother is likely to be concerned that a gap exists between the Bs and Ds, and only reassurance is required at this stage.

The average age for eruption of the upper permanent canines is between  and 2 years. However, a range of 0– 2 years has been identified in epidemiological studies. Variation occurs across the population, and each case must be assessed based on the general stage of development and eruption of all permanent teeth. As a very basic mnemonic for assisting in the assessment of canine develop ment, the phrase ‘Big Canines for Big School’ can be of some help. Knowledge of when the contralateral canine erupted or its degree of eruption would provide crucial information regarding whether the missing canine is likely to erupt spontaneously. Six months is con sidered a reasonable time period to monitor for contralateral tooth eruption prior to investigation. However, further information should be sought regarding:

• previous extractions
• previous trauma, particularly to the primary teeth
• Spacing or crowding in the relevant labial and buccal segments
• Whether the canine can be palpated buccally— this should be documented from the age of 9 years.

radiographs are likely to provide the greatest information regarding canine location. parallax periapicals or an orthopantomogram (OpT) with an upper occlusal would enable positioning of the canine to be de termined, whilst CBCT can be indicated where tooth resorption or cyst formation is suspected.

The normal innervation of the mandibular teeth is from the incisive branch of the inferior alveolar nerve (IAN). The teeth on the left side are supplied by the left IAN, and the teeth on the right side by the right IAN. In reality, there is often crossover of innervation at the midline of anatomical structures, and the mandible is no exception. It has been reported that in 42% of patients, there is crossover of innervation of the lower mandibular incisors from the contralateral IAN. However, given that, in this scenario, a buccal infiltration has been given, crossover supply from the contralateral IAN is unlikely, as the local anaesthetic has been deposited locally and this should anaesthetize both teeth. Although the nerve to the mylohyoid is classified as a motor nerve, a number of studies have identified that mandibular teeth can receive sensory innervation from sensory fibres travelling within this branch. They are thought to enter the mandible through the retromental foramina located on the lingual aspect of the mandible, superior to the genial tubercles. A lingual infiltration will help to anaesthetize accessory sensory neurons. The lingual and long buccal nerves may supply accessory nerves to the third mandibular molar teeth. The hypoglossal nerve is a purely motor nerve and not known to carry accessory sensory neurons.

The first action in this case would be to fast- bleep the stroke registrar! The signs and symptoms described indicate an upper motor neuron (UMN) lesion because the forehead has been spared, which is most likely to have been caused by an intracranial tumour or stroke. Knowledge of neuroanatomy is fundamental for this question, specifically the facial motor nucleus. The concept of UMN and lower motor neuron (LMN) lesions can be complicated to grasp. A UMN is any neuron carrying information within the central nervous system between the motor areas and CN nuclei. An LMN is any neuron carrying motor information from the CN nucleus to the target muscles and is the same as the peripheral nerve. When put simply, the area of the facial motor nucleus controlling the upper face receives its nerve supply from both sides of the cere bral hemispheres, whilst the part controlling the lower face receives its supply only from the contralateral hemisphere. Therefore, when a right UMN lesion occurs, the patient retains some control over the left fore head (from the left side of the brain), but loses motor control of the left lower face. However, when an LMN injury occurs, all neurons leaving the facial motor nucleus in the brainstem are affected, and as a result, all five peripheral branches of the facial nerve on the same side are af fected. This results in complete paralysis of all the muscles on the same side. Therefore, a left LMN lesion would affect the muscles on the left- hand side, rendering the left side of the face completely paralysed, e.g. Bell’s palsy, which is a diagnosis of exclusion when all other causes have been eliminated

The glossopharyngeal nerve provides parasympathetic fibres to the otic ganglion via the lesser petrosal nerve. post- synaptic parasympathetic fibres then pass to the parotid gland via the auriculotemporal nerve. The otic ganglion is one of four parasympathetic ganglia of the head, along with the submandibular, ciliary, and pterygopalatine ganglia. These gan glia are the site of synapse for parasympathetic fibres of the autonomic nervous system (ANS). The ANS can be subdivided into the sympa thetic, parasympathetic, and enteric nervous system. Of these subdi visions, the sympathetic (fight or flight) and parasympathetic (rest and digest) divisions are heavily involved in everyday functions such as heart rate, breathing, salivation, and swallowing. In the head, these ganglia are primarily secretomotor in function, i.e. they induce secretions from various glands (with the exception of the ciliary ganglion). Functions of the parasympathetic ganglia of the head include:

• pterygopalatine ganglion— secretomotor to the lacrimal gland and mucous glands of the mouth, palate, and nose. Known colloquially as the ‘hay fever’ ganglion. Supplied by CN VII— facial
• Otic ganglion— secretomotor to the parotid gland
• Submandibular ganglion— secretomotor to the sublingual and sub mandibular glands. Supplied by CN VII— facial
• Ciliary ganglion— motor to the constrictor muscle of the eye and the ciliary body (responsible for adjusting the shape of the lens in the eye to enable focusing on objects at various distances). Supplied by CN III— oculomotor. All the other answers listed are CNs that carry out important functions throughout the body, particularly the head and neck.

Oral epithelial and mesenchymal cells, along with migrating neural crest cells, are responsible for tooth formation. The interaction between these cell layers is essential for tooth development. These cell layers form the dental lamina, and within this lamina, the various stages of tooth development occur. These stages are named the bud, cap, and bell. During the bud and cap stages, the epithelial and mesenchymal cells proliferate to form the enamel organ and the dental papilla, respectively. The bell stage is defined by cell morphodifferentiation and histodifferentiation when enamel- and dentine- producing cells develop. enamel- forming ameloblasts develop from the cells of the inner enamel epithelial cells, whilst odontoblasts (dentine- producing cells) differentiate from ectomesenchymal cells (neural crest cells) that lie adjacent to the inner enamel epithelium. The resultant crown shape is determined by the inner enamel epithelium. Ameloblasts begin depositing enamel after dentine has begun to form, and this site of initial dentinogenesis and amelogenesis is referred to as the amelodentinal junction (ADJ). Ameloblasts subsequently pass through several stages, including a secre tory and maturation phase. AI is a group of hereditary conditions that can present with multiple phenotypic variations. The crown maturation (primary epithelial band) stage involves growth of the enamel crystals that have been deposited, and this phase accounts for the majority of the mineral found in enamel. Defects in the crown maturation stage are likely to present with hypomaturation AI, which would typically present in the manner described in the scenario. See Figure .9 which shows the initiation stage of human tooth development.

Children can be born with various kinds of cleft, which are reported to occur in approximately  in 700. There is a 2: male- to- female ratio when it comes to clefts involving the lip alone, and the ratio is inverted for cleft palates alone. This may be due to the fact that the palatine shelves elevate a week earlier in boys than girls. The face derives from five facial prominences that form during facial development:

• Two mandibular processes
• Two maxillary processes
• Frontonasal process.

The frontonasal process gives rise to the lateral and medial nasal pro cesses, which fuse with the bilateral maxillary prominences to form the upper lip, nose, and philtrum. The two medial nasal prominences fuse together at the midline to form the intermaxillary segment. As the maxillary prominence grows inwards, it fuses with the lateral nasal prominence to form the nasolacrimal groove. Failure of the maxillary prominence to fuse with the medial nasal process (or intermaxillary segment) results in a cleft lip, which can be uni- or bilateral. Inadequate fusion of the two nasal processes can result in a very rare median cleft lip. See Figure .8 which illustrates facial development.

General signs and symptoms of facial bone fractures include pain, swelling, bruising, haematomas, and bony steps. Specific signs related to is fractured), visual disturbances (if the orbit is fractured), paraesthesia (if nerves are damaged), or limited opening (if muscles are involved). Limited opening may be as a result of muscle entrapment or muscular spasm or purely due to localized swelling and discomfort. Fracture of the zygomatic arch may occur in isolation or, more commonly, in com bination with a zygomatic complex fracture. The origin of the tempor alis muscle is the temporal line at the superior aspect of the parietal bone of the skull. From here, it passes medial to the zygomatic arch and inserts onto the coronoid process of the mandible. If the zygomatic arch is depressed, the inferior fibres or the tendon of the temporalis will be impinged at the insertion to the coronoid process, therefore limiting the normal range of opening of the mandible on that side. Of the remaining options, only the masseter muscle attaches directly to the zygoma. However, its origin is the external surface of the zygomatic arch and, as such, depression would not lead to entrapment. The remaining options do not attach or pass under the zygomatic arch and therefore would not be affected.

There are three pairs of major salivary glands: the parotid, submandibular, and sublingual glands. As well as this, several hundreds of minor salivary glands are located within the submucosa of the mouth. These glands can become blocked or traumatized to form mucoceles or can undergo neoplastic change to become benign or malignant neoplasms. However, minor salivary glands are absent from the anterior hard palate and the gingivae. As a result, swellings identified in these regions are unlikely to have developed from salivary tissue, and this can be excluded from the differential diagnosis. Understanding the histology of the oral mucosa and soft tissues is important during assessment and diagnosis of disease.

The anatomical planes are key references used to describe and document clinical findings (see Figure .7 for anatomical position and planes). More recently, in dentistry, the use of advanced radiography techniques, such as CBCT, has gained popularity due to their ability to provide high- quality, three- dimensional (3D) images of complex anatomical structures. The technology is now frequently encountered in everyday scenarios, e.g. when assessing impacted teeth, root canal anatomy, and residual bone for implant placement. Whilst CBCT images can be reformatted to provide a 3D reconstruction, they are frequently viewed individually in each of the three anatomical planes:

1. Coronal (frontal)— a vertical plane that divides the body into anterior and posterior segments
2. Sagittal (longitudinal)— a vertical plane that divides the body into left and right segments
3. Transverse (axial)— a horizontal plane that divides the body into superior and inferior segments.

on lower posterior periapicals adjacent to, or overlapping, the root apices of the posterior teeth. It is often visualized as a radio- opaque line within the premolar– molar region. Knowledge of the anatomical attachment of this muscle is important when diagnosing pathology and assessing the proximity of the inferior dental nerve. Furthermore, the location of the mylohyoid ridge can have significant ramifications with regard to the spread of periapical infections. As the mylohyoid represents the inferior boundary of the mouth, roots that lie above the mylohyoid ridge are more likely to produce a sublingual swelling, as infection is likely to remain above the mylohyoid. By comparison, roots that pass below the mylohyoid attachment are more likely to enable spread of infection below the floor of the mouth into the sub mandibular region, i.e. a submandibular space swelling. The origins and insertions of the other muscles can be found in the recommended reading.

The temporomandibular joint (TMJ) comprises the mandibular fossa and articular eminence of the temporal bone and the head of the mandibular condyle. An articular disc separates the two bones, and the joint is sur rounded by a joint capsule which contains synovial fluid. The articulating surfaces are lined with fibrocartilage, and the articular disc is attached to the capsule and to bone by anterior and posterior fibroelastic bands. The anterior aspect of the articular disc and joint capsule is attached to the superior head of the lateral pterygoid muscle. The condylar head undergoes two major components of movement during opening: rota tion and translation. These allow elevation, depression, protrusion, and retraction of the mandible to take place. Initial rotation of the mandible about the terminal hinge axis (THA) oc curs within the inferior compartment of the joint capsule and accounts for the first 5– 20 mm of opening (total 45 mm). Following this, translation occurs in the upper compartment, and the mandibular head moves anteriorly onto the articular eminence. Therefore, in the absence of pathology, translation accounts for the majority of mouth opening

paget’s disease of bone is a rare chronic disease that involves disorganized bone remodelling. The disease can result in pain, fractures, and arthritis. It most commonly affects bones of the axial skeleton and is often localized to a small number of bones, including the pelvis. It can occasionally affect the cranial bones, with potential compression of neural tissue at the cranial foramina. Good knowledge of nerve pathways is therefore important during diagnosis and assessment of symptoms. In this particular scenario, trigeminal neuralgia is affecting the mandibular distribution of the trigeminal nerve. See Figure .5 (see Colour plate section) which shows a superior view of the cranial base.

Foramen and associated CNs include:

• Optic canal— optic nerve (CN II)
• Superior orbital fissure— oculomotor (CN III), trochlear (CN IV), abdu

cens (CN VI), ophthalmic branches of the trigeminal nerve

• Foramen rotundum— maxillary branches of the trigeminal nerve
• Foramen ovale— mandibular branch of the trigeminal nerve
• Stylomastoid foramen— facial nerve (CN VII)
• Jugular foramen— glossopharyngeal (CN IX), vagus (CN X), branches of

the accessory nerve (CN XI)

• Hypoglossal canal— hypoglossal nerve

Nerve supply to the maxillary teeth is via the maxillary branch of the trigeminal nerve (CN V2 ). The nerve enters the pterygopalatine fossa via the foramen rotundum. At this point, the posterior superior alveolar nerve bifurcates and passes inferiorly along the infratemporal surface of the maxilla to innervate the maxillary molars. The majority of the maxillary nerve continues as the infraorbital nerve, which con tinues through the pterygopalatine fossa and inferior orbital fissure to enter the infraorbital canal. The middle superior alveolar nerve branches along this course and runs to supply to upper premolars and, on occasions, the mesiobuccal root of upper first molars. The anterior superior alveolar nerve branches further along this course to supply the canine and upper incisors. Collectively, these branches form a plexus which can be referred to as the superior dental plexus. The upper anterior teeth can also be anaesthetized using an infraorbital block. For extractions, it is also necessary to anaesthetize the gingival tissues. The palatine gingivae are supplied by the greater palatine nerves, and the buccal and labial gingivae are supplied by the same superior alveolar branch that supplies the tooth. Buccal or labial infiltration will therefore anaesthetize the tooth and its labial or buccal gingivae, so only the palatal gingivae require additional infiltration. Knowledge of these nerve path ways is essential for all dental practitioners and can assist in the diagnosis of poorly localized, irreversible pulpitis when other special investiga tions have failed.

CN assessments are an important part of a junior dentist’s clinical know ledge. If asked to assess the CNs, the twelfth nerve (hypoglossal— XII) deviates to the affected side, i.e. if the patient had a large malignant lesion at the base of the left side of their tongue, the tongue would deviate to the left side. The glossopharyngeal nerve supplies sen sory function to the posterior part of the tongue. The lingual nerve is a branch of the mandibular nerve of the trigeminal nerve (CN V), which does not provide motor function to the tongue. The pharyngeal plexus supplies the palatoglossus muscle of the tongue, which is a small extrinsic muscle of the tongue that passes from the soft palate into the tongue. Motor fibres of the pharyngeal plexus supply the majority of the muscles of the soft palate and the constrictor muscles. The motor fibres travel to the muscles via the vagus nerve but are derived from the cranial root of the accessory nerve (CN XI)

Branches of the external carotid artery provide the vascular supply to the majority of structures in the facial region. The maxillary artery branches from the external carotid artery and passes deep to the head of the mandibular condyle. It supplies numerous oral structures, including the teeth and the muscles of mastication. The inferior alveolar artery branches from the first part of the maxil lary artery and supplies the lower teeth. The teeth and associated structures in the maxilla are supplied by the posterior, middle, and anterior superior alveolar arteries. These are branches of the third, or pterygopalatine, part of the maxillary artery, which branches in the pterygopalatine fossa. The facial artery and the transverse facial arteries supply the tissues of the face, and the lingual artery supplies the tongue. The facial artery runs in close proximity to the angle of the mandible before continuing up into the cheek. Great care must be taken when performing surgery (incisions) in the lower molar region, especially when localized swelling may distort the soft tissues. Inadvertent injection of local anaesthetic into the facial artery has also been reported, with subsequent blanching of the soft tissues of the cheek.

The direct technique for achieving inferior alveolar anaesthesia is one of the most common procedures carried out in dentistry and provides anaesthesia to the entire quadrant of mandibular teeth, as well as associated soft tissues. The needle passes medially to the internal oblique ridge and lateral to the pterygo- mandibular raphe at a height of approximately  cm above the occlusal plane. After passing through the buccinator muscle, the needle travels along the inside of the mandibular ramus into the pterygomandibular space and is in serted approximately 20– 25 mm until it touches bone. The needle should be withdrawn slightly before local anaesthetic is deposited. At this point, the needle tip will be superior to the mandibular foramen, medial to the mandibular ramus and lateral to the medial pterygoid and sphenomandibular ligament. The attachment for the sphenomandibular ligament, or lingula, will be slightly inferior and anterior to the final needle position. Upon withdrawing, continued injection of solution is likely to anaesthetize the lingual nerve. It is important to remember the bony reference points when administering the local anaesthetic. The buccinator muscle passes anteriorly from the pterygomandibular raphe to insert into the orbicularis oris anteriorly where it contributes to the modiolus. It forms the lateral aspect of the oral cavity and inserts into the lateral surfaces of the maxilla and mandible. It is supplied by the facial nerve [cranial nerve (CN) VII)]. See Figure .2 which illustrates the mandible.

The lingual nerve supplies general sensation to the anterior two- thirds of the tongue, the floor of the mouth, and the lingual aspect of the mandibular gingivae. It passes along the lingual aspect of the mandible and is often in close proximity to the bone forming the sockets of the mandibular wisdom teeth. As a result, it can be easily damaged during extraction. The reported incidence of lingual nerve injury following third molar surgery (when a lingual flap is not raised) varies significantly from study to study; permanent injury is thought to occur in approximately 0– 2% of cases. Lingual nerve damage following third molar surgery is more likely than damage to the inferior alveolar nerve, and risk factors such as distoangular impactions, inappropriate technique, or lack of experience can increase a patient’s risk. Lingual nerve damage is often temporary, and recovery is reported in the majority of cases. Lingual retraction during lower wisdom tooth extraction remains controversial. However, some clinicians claim a reduced risk of permanent lingual nerve damage as justification for use of this technique. Incidence data do not support this theory, with higher permanent damage documented. The hypo glossal nerve provides motor function to the muscles of the tongue. The inferior alveolar nerve runs within the mandible to supply the mandibular teeth and exits the mental foramen to become the mental nerve, which innervates the skin, labial gingivae, and soft tissues of the chin. The nerve to the mylohyoid provides motor control to the mylohyoid muscle. The chorda tympani nerve supplies special sensory function (taste) to the anterior tongue

Formation of the bony skeleton begins in utero as early as 6 weeks post- fertilization. protection, support, and production of blood cells are vital functions of bone. Bone formation (osteogenesis) relies upon the gradual. Skeletal derivatives of the pharyngeal arches Pharyngeal arch Cranial nerve Muscular structures Skeletal structures Vascular structures First (mandibular) V— trigeminal Muscles of mastication, anterior belly of the digastric, tensor tympani, tensor veli palatini Meckel’s cartilage (contributes to mandible), incus, and malleus Maxillary artery Second (hyoid) VII— facial Muscles of facial expression, posterior belly of the digastric, stapedius, stylohyoid Styloid process, stapes, upper part of body of the hyoid and lesser cornu Hyoid and stapedial artery Third IX— glossophary-ngeal Stylopharyngeus Lower part of body of the hyoid and greater cornu Internal carotid artery Fourth X— vagus pharyngeal constrictors, cricothyroid, levator veli palatini Thyroid cartilage right subclavian artery and aorta reproduced from Atkinson Martin e, Anatomy for dental students, replacement of tissue with bone by osteoblasts in a process known as ossification. Two main types of ossification exist: endochondral and intramembranous. endochondral ossification occurs in the majority of bones in the body and involves gradual replacement of a cartilage model with bone. The genetically determined cartilage model grows via expansion (endosteal ossification) and new cartilage production on the outer surface (ectopic ossification), prior to fibroblasts differentiating into osteoblasts and depositing bone. In contrast, intramembranous ossification involves primitive connective tissue (mesenchyme) differentiating into osteoblasts. The osteoblasts secrete a matrix which is subsequently calcified. The mandible and maxilla are both formed via intramembranous ossification, along with numerous other facial bones, the flat bones of the skull, and the clavicles, to name a few. remodelling (periosteal ossification) is heavily involved in both ossification processes, as the bones formed are maintained via dynamic osteoblastic– osteoclastic activity. This process is responsible for the changes seen in the alveolar ridge fol lowing a tooth extraction. It is important to note that, whilst calcification occurs during ossification, the terms are not synonymous, as calcification can take place without the formation of bone. Intramembranously ossified bones: skull vault, squamous part of the temporal, mandible, premaxilla, maxilla, zygoma, wings of the sphenoid. Endochondrally ossified bones: petrous part of the temporal, ethmoid, body of the sphenoid, basilar part of the occiput.

The pharyngeal apparatus comprises the pharyngeal arches, pouches, membranes, and grooves. Specifically, several pairs of pharyngeal arches begin to develop, following migration of neural crest cells into the head and neck regions during the fourth embryonic week. each arch has a car tilaginous component, which develops into skeletal structures and a mus cular component that develops into the muscles of the head and neck. A cranial nerve also develops with each arch, which goes on to supply the muscular and mucosal derivatives of the arch.

The management of developmental white spot lesions is frequently an aesthetic concern and can be challenging to manage. The four traditional management strategies are remineralization, masking with bleaching, microabrasion, or restoration. Most clinicians would wish to avoid formal restoration, if possible, particularly in younger patients. However, the most conservative measures are inconsistent in their results, and furthermore, microabrasion can remove up to 360 μm of enamel and leave a rough surface.

resin infiltration is a contemporary technique that uses low-v iscosity resin to fill subsurface porosities. It was initially developed for preventing progression of early carious lesions. In white spot lesions, the resin fills the subsurface porosities, increasing the refractive index to a value similar to that of the surrounding enamel (.52). prior to infiltration, the porosities are filled with air or water, which has a much lower index (air has a refractive index of ) and makes the lesion more obvious to the eye. Although results are not 00% successful, they are promising and can provide acceptable results without the need for further treatment.

Keywords: resin infiltration, aesthetic concerns.

→ Kim S, Kim eY, Jeong TS, Kim JW. The evaluation of resin infiltration for masking labial enamel white spot lesions. International Journal of Paediatric Dentistry. 20;2:24– 8.

A vast array of suture materials are available in modern medicine, and often numerous materials will be appropriate for a given situation. In relation to modern periodontal microsurgery (particularly in the aesthetic zone), a number of basic principles apply to material choice. In general, monofilament sutures are preferential to multifilament fibres, as they do not ‘wick’ bacteria into the wound, which aggravates the inflammatory response. Secondly, in delicate tissues (e.g. the dental papilla), finer and less traumatic sutures are recommended, as this promotes quicker wound healing and causes less chance of disruption to the blood supply.

Synthetic monofilament fibres are usually considered the material of choice, as they are least traumatic and only induce mild tissue reactions. Despite this, some clinicians favour the use of polyglycolic acid, as good knot tension can be achieved.

Black silk is a braided multifilament material which produces one of the higher tissue reactions, and although it has good handling properties, it is infrequently used. polyester is again a multifilament fibre and not frequently used in dentistry. Vicryl^® (polyglycolic acid) is a multifilament, synthetic, resorbable material. In smaller sizes, it may be appropriate for the task at hand; however, #4.0 is generally considered too large. It is frequently used in dento- alveolar surgery.

poliglecaprone (e.g. Monocryl^®) would be a more suitable resorbable material, as it is a monofilament fibre and has high initial strength during the first few days of wound healing. It is, however, more expensive. The most appropriate choice would therefore be 6.0 polypropylene (prolene^®), a small monofilament, non- resorbable suture which induces minor tissue reactions. Being non-r esorbable, there is less risk of dislodgement and wound dehiscence during the critical early healing stages, compared with resorbable sutures.

Keywords: periodontal surgery, microsurgical, suture.

→ Kurtsmann G. Suturing for success. Dentistry Today. Available at: http:// www.dentistrytoday.com/ periodontics/ 359- suturing- for-  surgical- success

→ Velvart p, peters C. Soft tissue management in endodontic surgery. Journal of Endodontics. 2005;3:4– 6.

Fixed and removable prostheses rely upon the accuracy of working impressions. In implant dentistry, this accuracy has greater relevance, particularly where suprastructures are used to join implants. Any discrepancies prevent passivity of fit and may cause complications (e.g. fracture of veneering material or marginal bone loss).

Contemporary elastomeric materials have high accuracy and good dimensional stability. polyethers are generally favoured over addition pVS in the scenario, as they have greater rigidity and therefore are thought to better retain the impression copings in the correct position during casting. It is important though that polyethers are poured within  hour, as moisture absorption can cause distortion. pVS materials are suitable alternatives, as studies have shown similar accuracy to polyethers. However, results are less reproducible.

Some clinicians may still use impression plaster for the above situation, but it is only applicable to edentulous cases with no undercut. Furthermore, there is significant cumulative distortion, following the pouring of the master model.

Hydrocolloids are not accurate or rigid enough for this application.

The era of digital dentistry is beginning to revolutionize prosthodontics, and with future advances, intraoral scanning may supersede conventional impression techniques.

Keywords: minor undercut, open- tray impression, implants.

→ Donavon T, Chee W. Impression materials: a comparative review of impression materials most commonly used in restorative dentistry. Dental Clinics of North America. 2004;48:445– 70.

→ Hoods-M oonsammy V, Owen p, Howes D. A comparison of the accuracy of polyether, polyvinyl siloxane, and plaster impressions for long- span implant-s upported prostheses. International Journal of Prosthodontics. 204;27:433– 8.

Various active ingredients have been investigated to assess their potential to protect against erosion, with limited conclusive results. Some compounds, such as Cpp- CAp, calcium nanophosphate, titanium fluoride, and stannous fluoride, have shown potential in reducing the impact of erosion. Over time, these compounds build a protective glaze/ coatings on the tooth surface. Alternatively, some clinicians would prescribe higher- strength sodium fluoride (.% in patients over 6 years of age), but this would help to remineralize the lost ions, rather than prevent dissolution. Although the actual quality of the evidence is weak and there are numerous methodological challenges which reduce the external validity of results, stannous fluoride toothpastes are readily available on the high street and may provide greater benefit to patients over sodium fluoride alone. Furthermore, as the product cost is low (compared to Cpp- ACp or a prescription) and this type of fluoride formulation is not detrimental, then the authors would suggest its use to supplement a preventative programme until further evidence is available. Clinicians should also remember that standard dietary advice and any necessary medical management are necessary and more important than the active ingredient of toothpaste.

Arginine is generally used as a desensitizing agent, and sodium lauryl sulfate is a foaming agent in toothpastes.

Keywords: erosion, widely available, toothpaste, protective.

→ Carvalho FG, Brasil VL, Silva Filho TJ, Carlo HL, Santos rL, Lima BA. protective effect of calcium nanophosphate and Cpp- ACp agents on enamel erosion. Brazilian Oral Research. 203;27:463– 70.

→ Hove LH, Holme B, Young A, Tveit AB. The protective effect of TiF4, SnF2 and NaF against erosion-l ike lesions in situ. Caries Research. 2008;42:68– 72.

→ Wang X, Megert B, Hellwig e, Neuhaus KW, Lussi A. preventing erosion with novel agents. Journal of Dentistry. 20;39:63– 70

Composites placed at an increased occlusal vertical dimension (OVD) for toothwear are becoming common practice. The chosen material needs to have good mechanical properties to resist the increased occlusal loads placed on these ‘proud’ restorations, along with good aesthetic properties. Traditional microhybrid composites combine large and small filler particulars to increase the filler content. Higher filler contents generally improve the mechanical properties and reduce polymerization shrinkage. Old microfill composites utilized smaller filler particles, which reduced the size of surface irregularities and improved surface smoothness and appearance. However, this negatively impacted on mechanical properties, as the glass content was reduced.

The introduction of nanoparticles to modern composites has been claimed to maintain the mechanical properties of the microhybrid, but also to harness the aesthetic properties of microfill composites. Therefore, in a case like in the scenario, a nanohybrid composite would be the most appropriate choice of materials. A conventional microhybrid material would be a suitable alternative, as it has a proven track record.

Keywords: composite, worn, teeth, increased OVD.

→ Moraes rr, Gonçalves L de S, Lancellotti AC, Consani S, Correr- Sobrinho L, Sinhoreti MA. Nanohybrid resin composite: nanofiller loaded materials or traditional microhybrid resins. Operative Dentistry.

2009;34:55– 7.

In vital pulp therapy, CH was traditionally the gold standard until newer materials, such as MTA [a type of bioactive endodontic cement (BeC)], became available. When applied directly to pulp tissues, CH forms a superficial layer of necrosis, which contains calcium deposits. These act as foci for calcification, and subjacent pulp cells differentiate into odontoblasts to produce reparative dentine and a hard tissue barrier. Furthermore, the high pH is thought to solubilize proteins and growth factors trapped in the adjacent dentine, which stimulates pulp cell differentiation. BeCs have been shown to release a greater number of growth factors than CH.

BeCs differ in that they have been demonstrated to induce less inflammation at the interface and cause greater proliferation of odontoblasts. Some research suggests that the formation of CH within BeCs is responsible for this finding (again solubilizing cytokines from the surrounding dentine). Additionally, BeCs biocompatibility have been linked with the material’s ability to form hydroxyapatite. Biologically, BeCs are more biocompatible, and results suggest that histologically dentine formation is more regular, less porous, and in increased amounts.

Additionally, the ability to bond to dentine is important in the success of pulp capping. Mechanically, BeCs have been shown to have an ionic bond to the dentine, which may limit bacterial penetration. Both materials display antibacterial properties, and neither material has been shown to be obtundent.

Keywords: direct pulp cap, new calcium silicate, calcium hydroxide, biological reason.

→ Modena KC, Casas- Apayco LC, Atta MT, et al. Cytotoxicity and biocompatibility of direct and indirect pulp capping materials. Journal of Applied Oral Sciences. 2009;7:544– 54.

Various types of corrosion can affect dental materials, and the surrounding environment plays a role in this. When dissimilar metals are placed within an electrolytic solution, there is potential to create an electrochemical cell (e.g. a chemical battery), otherwise known as a galvanic cell. It has been reported that when amalgam is placed adjacent to gold in saliva, a galvanic cell can be induced, leading to galvanic corrosion. This leads to surface staining with a silver brown colour in a ring around the contact point. However, it is suspected that it is the presence of free mercury that results in galvanic corrosion. This reaction is short- lived, with little mercury remaining after about  hour and almost no residual current after  day.

The effects of this corrosion are clinically insignificant with regard to the alloy properties, but it has been reported that this galvanic current can occasionally cause short-l ived mild pain. replacement of the restoration is not normally required.

Keywords: amalgam, gold, silver/ brown circular stain, contact point.

→ Fusayama T, Katayori T, Nomoto S. Corrosion of gold and amalgam placed in contact with each other. Journal of Dental Research. 963;42:83– 97.

→ Upadhyay D, panchal AD, Dubey rS, Srivastava VK. Corrosion of alloys used in dentistry: a review. Materials Science and Engineering. 2006;432:– .

Traditionally, dental alloys have been produced by casting methods utilizing the lost wax technique; this method is labour- intensive and time- consuming. CAD/ CAM has become readily available in dentistry for prosthesis production. CAD/C AM methods can either be subtractive (i.e. milling of pre- manufactured blocks) or additive (SLM, stereolithography, etc.). SLM works by high-p owered lasers selectively fusing areas of a metal powder, layer upon layer, to the designed 3D structure. This process has the advantage over milling of being able to produce hollow 3D structures. In comparison to traditional casting methods, porosities are greatly reduced, which significantly improves the alloy’s physical properties. The accuracy is also comparable, if not better, than casting.

The σ- phase of Co- Cr makes the material more brittle. This is related to the composition of the alloy, and not the production process. The addition of molybdenum increases the γ- phase (which demonstrates improved strength), but this is not related to the manufacturing process. The addition of tungsten helps to reduce the σ- phase.

Keywords: CAD/ CAM, SLM, stronger.

→ Koutsoukis T, Zinelis S, eliades G, Al- Wazzan K, rifaiy MA, Al Jabbari YS. Selective laser melting technique of Co- Cr dental alloys: a review of structure and properties and comparative analysis with other available techniques. Journal of Prosthodontics. 205;24:303– 2.

Composite is primarily composed of a resin matrix and an inorganic filler. The filler improves the material characteristics by reducing shrinkage, increasing compressive strength, and improving wear rate. Fillers are commonly composed of glass particles (e.g. aluminoborosilicate), and the size of the particles is used to classify the type of composite (e.g. microfilled, nanofilled, nano-h ybrid, etc.). The composition of the filler particles significantly influences the physical properties of the resultant composite.

Unfortunately, resins and fillers do not bond chemically, and as such, an intermediary silane coupling agent is required. Silanes have both an inorganic and an organic end to their molecule, allowing the chemical linkage of the resin and filler. Contact of the composite with air inhibits the polymerization process, leaving an unreacted surface that can be used for future bonding. However, in old composites, this is inevitably worn (or polished) away, leaving a surface layer predominantly composed of exposed inorganic filler. The original silane coating again will have been worn away from exposure to the oral environment, and therefore, to optimize the bond when repairing composites, a fresh silane layer should be applied. Some newer universal bonding agents may already contain silane.

Barium oxide is added for its radio- opacifying properties. Camphorquinone is the source of free radicals for the polymerization reaction of light-c ured composites. Hydroquinone prevents premature polymerization. TeGMA is a low- weight resin monomer added to improve handling characteristics and reduce viscosity.

Keywords: composite, repair, prior to bonding.

→ Staxrud F, Dahl J. Silanising agents promote resin- composite repair. International Dental Journal. 205;65:3– 5.

For a long time, metallo-c eramic crowns were the mainstay of aesthetic indirect restorations due to their greater resilience than traditional porcelain jacket crowns. The advent of dentine bonding and modern high- strength ceramic restorations has led to alternative options becoming available that are generally considered to be more aesthetic due to their optical properties. However, there is still a place for metal- ceramic restorations as they have a proven track record, are durable in high- stress situations, and provide a good compromise between aesthetics and tooth reduction. High-s trength ceramics generally require greater circumferential tooth reduction.

The mechanical and aesthetic properties of the materials in metal- ceramic crowns dictate the space. A relatively thin, uniform layer of porcelain supported by metal is the strongest but often does not provide acceptable aesthetics. The absolute minimum requirements for porcelain is 0.7 mm, and metal 0.3–0 .5 mm. However, to avoid an opaque-looking  restoration, .5– 2 mm of incisal reduction is advocated. Therefore, in this scenario, as  mm of incisal clearance already exists, a minimum of 0.5- mm further reduction is needed.

Keywords:  mm of space, desired incisal level, metallo-c eramic crowns.

→ ricketts D, Barlett D. Advanced Operative Dentistry: A Practical Approach (st ed.). Churchill Livingstone, London; 203.

MTA has become commonly used for the formation of an apical plug in endodontics, due to its biocompatibility. One of the adverse effects is the resultant discoloration of the tooth. Although the exact mechanism is not yet fully understood, it is suspected to be related to the presence of the radio-o pacifier bismuth oxide. A number of potential interactions have been hypothesized. It has been suggested that bismuth oxide can interact with collagen in the dentine to form a dark precipitate. Alternatively, some research suggests that residual sodium hypochlorite can react with bismuth oxide to form a dark precipitate. In efforts to reduce the discoloration of MTA, manufacturers have tried to reduce the content of heavy metals. Iron content has been reduced in white MTA, yet discoloration remains a documented complaint.

Calcium silicate cements with alternative radio- opacifiers, such as zirconium oxide, may reduce discoloration risks in areas of aesthetic concern. One further suggestion has been made that sealing the dentine prior to placement of MTA may reduce discoloration.

endodontic sealers may cause minor discoloration, but this is not as consistent as with MTA. rMGIC is not known to stain teeth.

Keywords: marked discoloration, MTA.

→ Yun D, park SJ, Lee Sr, Min KS. Tooth discoloration induced by calcium- silicate- based pulp- capping materials. European Journal of Dentistry. 205;9:65– 70

residual monomers in dentures can cause mucosal irritation and theoretical reductions in strength (as the polymerization conversion is reduced). The international standard for residual monomer content is

2.2%. Manufacturers’ curing cycles vary in method but typically have a prolonged period of around – 2 hours at 70°C, followed by a final boil at 00°C for half hour to  hour. Despite several traditional studies investigating curing cycle optimization, the reference below demonstrates that there is no scientific basis to account for these two temperatures in the curing cycle. Curing at 95°C overnight would achieve residual monomer levels consistently below the required standard of 2.2%. Achieving similar levels at 70°C would require curing times in excess of 300 hours. The justification for using the protocol outlined above is for practicality, energy efficiency, and concerns of rapid temperature increases boiling the monomer.

excess powder would lead to granular porosities from unreacted polymer powder. Heating rapidly above acrylics boiling point would lead to gaseous porosities. packing at the ‘wet sand’ stage would likely lead to an under- filled mould, and under- compression would result in an overly thick denture base and an unwanted increase in vertical dimension.

Keywords: replacement, denture, burning/i tching sensation, excess monomer.

→ Lung C, Darvell B. Minimization of the inevitable residual monomer in denture base acrylic. Dental Materials. 2005;2:9– 28.

The recognized way of classifying colour was devised by Albert Munsell. He divided colour into three components to precisely define every colour: hue, chroma, and value. Hue is the ‘actual’ colour and is either red, yellow, green, blue, or purple, or somewhere within that circular scale. This natural order of colour makes up Munsell’s colour wheel. Teeth have hues of reds or yellows. This is reflected by the L and r values on the Vita 3D shade guide^™; ‘L’ represents a yellower hue, and ‘r’ more red (i.e. left and right shifts on the colour wheel). Chroma is the saturation of a colour, i.e. the colour intensity. On the 3D shade guide, this is denoted by the ‘M’ value. The value is how light or dark an object is (i.e. white to black) and, on the shade guide, is represented by the numbers  to 5. When using the shade guide, the value is selected first, then the chroma (‘M’ value), and finally, if required, the hue is adjusted (‘L’ and ‘r’ values). The 3D shade guide provides a comprehensive, systematic chart covering standard tooth colours. In comparison, standard shade guides generally cover a selection of common colours. Modern technological advancements include chairside spectrometers to aid colour selection. polarized or greyscale images (with shade tabs in them) can help to select the correct hue and value, respectively.

Keywords: dark, element of colour, Vita 3D shade guide^™.

→ Vita 3D shade guide user manual. Vita Zahnfabrik. Available at: https:// www.vita- zahnfabrik.com/ en/ VITA- Toothguide- 3D- MASTer- 26230,27568.html

The management of flabby ridges can be difficult. The basic principle comes down to the argument of whether the denture- bearing area should be recorded under compression or relaxation (mucocompressive or mucostatic). With fibrous ridges, it is generally considered that a mucostatic impression of the hypermobile tissue is desirable, as it is more stable during rest (the soft tissue would recoil and dislodge the denture if recorded under compression).

Therefore, a selective pressure technique is used to record the normal tissues under slight compression and the flabby tissue at rest for optimal support and retention. A variety of techniques have been suggested in the literature, each one as an alternative method of achieving a mucostatic impression. They all tend to employ a custom-m ade tray, with some form of venting or spacing over the flabby tissue. The choice of material is important, as the viscosity is required to be low enough that, when pressure is applied to seat the tray, the resistance of the flabby tissue is greater than the inherent stiffness of the material causing it to flow and not displace the tissue. Traditionally, plaster of paris was used, but the contemporary replacement is low- viscosity silicone.

Keywords: flabby ridge, window technique.

→ poonam Sr, Agrawal H. A review of prosthodontic management of flabby ridge conditions in maxilla and mandible by noninvasive techniques and with the use of contemporary materials. Guident. 202;5:24– 32.

Dental amalgam is an alloy composed primarily of silver, tin, copper, and mercury. Its setting reaction has been refined over many years. The reaction creates a fine balance between various compounds (referred to as gamma phases), with each influencing the property of the amalgam. A crumbly or grainy amalgam has been under- triturated, and the material is often unusable as insufficient wetting of the alloy has occurred. Over- trituration would result in an amalgam mix that is excessively sticky.

Amalgam contraction occurs with all amalgams during the first hour, and this would not noticeably influence the workability of the material.

Moisture contamination remains a problem with zinc- containing amalgams, as this can result in delayed expansion of the amalgam.

Burnishing improves the marginal integrity of amalgams and, as such, reduces the risk of leakage at the margins.

Keywords: amalgam, crumbly, unusable.

The bonding mechanism of the composite is micromechanical. Following demineralization of the surface of the dentine with an etchant, a primer and a bonding agent are used to create a hybrid layer to allow the hydrophobic composite to bond to the ‘wet’ or hydrophilic dentine surface. This hybrid layer creates resin tags within the exposed dentinal tubules, giving micromechanical retention. The reference listed below gives an excellent summary of the evolution of dentine- bonding agents. The concept of ‘wet bonding’ was brought about when it was discovered that overdrying of the surface led to a reduction in bond strength. At a microscopic level, when the dentinal surface is etched, the demineralization process leaves a matrix of collagen fibrils exposed, which is supported by residual water. If overdried, this layer collapses (collagen collapse) and the resulting hybrid layer is thin and weak, potentially decreasing the bond strength. Conversely, if the residual water is not expelled, then water globules will form within the resin layer, again resulting in a weaker bond and the risk of future degradation. With modern combined primers and bonding agents, two coats should be applied to thoroughly expel the residual water and optimize the bond. prevention of collagen collapse is key to the ‘wet bonding’ principle.

Keywords: composite, wet bonding.

→ pashley D. The evolution of dentin bonding. Dentistry Today. 2003.

Available at: http:// www.dentistrytoday.com/ materials

Gold onlays are commonly used in the management of toothwear to restore posterior teeth because of the limited tooth reduction required. However, their preparation design frequently lacks retention and resistance form. They therefore rely on adhesive cements to retain them in situ. From the list given, chemically active resin cements are the most suitable option. All the other options exhibit insufficient strength to resist the functional forces placed upon a restoration lacking resistance or retention form. resin cements are stronger, with high enough bond strengths to retain onlay-t ype restorations. It is important to remember that resin cannot be light-c ured through gold restorations and, as such, dual- or chemically cured resin cement should be used. One of the challenges with bonding to gold is the inherently inert nature of the material and the lack of an oxide layer produced. Chemically active cements, such as panavia^®, can bond to noble metals, but methods such as heat treating or tin plating have been advocated to improve the bond strength. However, despite these suggestions, evidence exists to show that air- abrading (sand blasting) the fitting surface alone provides adequate micromechanical retention to achieve a successful clinical outcome.

Keywords: gold onlays, minimal retention or resistance form, cementation.

→ Chana H, Kelleher M, Briggs p, Hooper r. Clinical evaluation of resin- bonded gold alloy veneers. Journal of Prosthetic Dentistry.

Amalgam is commonly classified by the shape of their silver-t in particles, which can be spherical, lathe-c ut, or admixed. Lathe-cut amalgam  hardens more slowly and gives a longer working time. The remaining answers refer to properties of spherical amalgam, except answer D which is another property of lathe- cut amalgams.

Spherical amalgam can achieve a smoother finish because the alloy particles do not impinge upon each other as they do in lathe-c ut amalgams. It is easier to condense because there is less friction between the spherical particles than there is in lathe-c ut amalgams. Also, spherical alloys have less mercury, which results in greater shrinkage, so contacts are likely to be less tight.

Older amalgams underwent net expansion as the setting reaction progressed. Modern- day amalgams show net contraction, the reasons for this being:

• Older amalgam had larger alloy particles and a higher mercury content
• Before amalgamators were available, amalgam was mixed by hand trituration, with more vigorous trituration, resulting in more contraction.

Admixed amalgam demonstrates properties between spherical and lathe- cut amalgams.

Keywords: struggling to pack, before it sets, lathe- cut.

The increased organic composition of dentine and the presence of dentinal fluid, compared with enamel, mean that a hybrid layer has to be formed in order to allow the hydrophobic resin to bond to the dentinal surface. To allow this to happen, modern bonding systems have three stages: etching, priming, and bonding. etching demineralizes the enamel or dentine surface to create microporosities or prepare the surface for bonding. It also removes the smear layer. The primer has small hydrophilic monomers, along with solvent molecules, that improve the wettability of tooth structure and allow infiltration of the resin molecules into the exposed collagen fibrils to form a hybrid layer when bonding to the dentine. The bond component is either lightly filled or unfilled resin that combines with the hybrid layer to form a hydrophobic surface for the composite to bond to.

Manufacturers have tried to simplify the bonding process by combining various stages. Self- etching systems have had their priming monomers modified to incorporate carboxylic or phosphate acid groups. When bonding to enamel, in comparison to phosphoric acid, self-e tching primers do not produce such high bond strengths, as the acid primers cannot etch as deeply or as uniformly. The results to the dentine are, however, similar to conventional etching methods and furthermore may reduce the technique sensitivity of bonding to the dentine, as there is no risk of overdrying the dentine and collapsing of the exposed collagen fibres. For these reasons, when using a self-e tching system for composite restoration, selective etching of enamel is recommended. Keywords: self- etch adhesive bonding system, modified, etching. → Ozer F, Blatz M. Self-e tch and etch-and- rinse adhesive systems in  clinical dentistry. Compendium of Continuing Education in Dentistry.

203;34:2– 4.

There are various factors influencing patients who have hypersensitive gag reflexes. The gag reflex itself is ‘an involuntary contraction of the muscles of the soft palate or pharynx that causes retching’. It is an important protective reflex present in human physiology. It can be described as either somatic (stimulated by touching areas of the mucosa) or psychogenic. The severity of gagging can be graded  to 5. Above- moderate gagging (grade 3) routine dental treatment can be challenging. For denture wearers with hypersensitive gag reflexes, coverage of the palate is a frequent complaint that they associate with the problem. However, poor retention and an overly thick palate can contact the dorsum of the tongue and stimulate the gag reflex. provision of a CoCr denture with good retention and a thin major connector may help from both a physiological and a psychological perspective.

Yield strength is the point at which permanent plastic deformation (proportional limit) occurs within the material. CoCr has a yield strength in the region of 600–7 00 Mpa, giving it good flexural rigidity, and allows denture bases of thin section. Strength in thin section means less palatal coverage and smaller connectors are required. Keywords: CoCr, property, thinner, major connector.

→ Al- Jabbari Y. physico- mechanical properties and prosthodontic applications of Co-C r dental alloys: a review of the literature. Journal of Advanced Prosthodontics. 204;6:38– 45.

→ Forbes- Hayley C, Blewitt I, puryer J. Dental management of the ‘gagging’ patient— an update. International Journal of Dental and Health Sciences. 205;3:423– 3.

Fibre posts should be bonded into the root canal system. This aids not only retention, but also helps to distribute the forces along the root canal system. In order to do this, resin- based cement is required. resin- based cements can be light-c ured, chemically cured, or dual-cured. The reliable  curing depth of conventional composite is around 2 mm, which would not normally be sufficient to cure to the full depth of the post preparation. However, translucent fibre posts can transmit the light along the length of the post and initiate the curing reaction. The problem with this is that the curing reaction will be towards the post. The enormous c- factor could easily lead to the dentine bond being broken. Although there is evidence to suggest that light- cured and dual systems have similar bond strengths along the root regions for this type of post, the authors would argue that dual-c ured cement (the chemically cured component) is more likely to reliably achieve full curing throughout the lute and therefore is preferable. Another key element to a successful bond is the use of a dual- cured/ chemically cured bonding agent.

It is important to realize that achieving a reliable bond to the root dentine can be challenging, and debonding of fibre posts is a common reason for failure.

Keywords: glass- fibre post, cement.

→ Barfeie A, Thomas MB, Watts A, rees J. Failure mechanisms of fibre posts: a literature review. European Journal of Prosthodontics and Restorative Dentistry. 205;3:5– 27.

→ Giachetti L, Scaminaci russo D, Baldini M, Bertini F, Steier L, Ferrari M. push- out strength of translucent fibre posts cemented using a dual- curing technique or a light- curing self-a dhering material. International Endodontic Journal. 202;45:249– 56.

Sodium hypochlorite remains the gold standard for chemical disinfection of the root canal system. It is a highly effective antimicrobial agent that dissolves organic matter and helps lubricate the root canal system. The major disadvantage of sodium hypochlorite is that it is unable to remove the smear layer created during mechanical cleaning of the canals. The smear layer (composed primarily of inorganic material and approximately 5 μm in thickness) blocks dentinal tubules and remains a potential reservoir for pathogens. removal of the smear layer has been shown to improve endodontic outcomes, especially in rerCT. Alternative irrigants are therefore available to help remove the inorganic matter that remains (e.g. eDTA, citric acid). These irrigants chelate the inorganic components that make up the smear layer and help remove the associated bacteria. Furthermore, the underlying dentinal tubules are exposed, and it is thought that this increases the penetration of the sealer and subsequently improves the adaptation of the root canal filling.

HeBp (- hydroxyethylidene- ,- bisphosphonate), or etidronate, is gaining popularity within the endodontic community as a possible alternative chelating agent. However, eDTA remains the most widely used and evidence- based chelating agent at present.

Keywords: inorganic matter, irrigant, root canal.

→ Hülsmann M, Heckendorff M, Lennon A. Chelating agents in root canal treatment: mode of action and indications for their use. International Endodontic Journal. 2003;36:80– 30.

→ Shavravan A, Haghdoost AA, Adl A, rahimi H, Shadifar F. effect of smear layer on sealing ability of canal obturation: a systematic review and meta- analysis. Journal of Endodontics. 2007;33:96– 05.

Addition- cured silicones are based on polymers of vinylsiloxanes. One half of the material contains polydimethylsiloxane with some methyl groups replaced with hydrogen, and the other half contains polydimethylsiloxane with some methyl groups replaced with a vinyl group. When mixed in the presence of platinum, a cross- linking reaction occurs between the single hydrogen groups and the vinyl groups. Clinically, due to the inherently hydrophobic nature of these polymers, the presence of moisture can result in air blows.

The addition of surfactants (a molecule which reduces the material’s surface tension) is one method some manufacturers have used to combat this. Surfactants are bidirectional molecules which have both a hydrophobic and a hydrophilic end. Their addition to pVS materials lowers the surface tension and causes a reduction in the contact angle the material makes with water. This improves the wettability of the material and theoretically decreases the risk of air blows. However, the authors would still recommend that the impression surface is dried thoroughly (particularly in crown and bridge work) to improve the quality of the impression.

Drags may occur when the material is removed before it is set or where undercut is present and high- viscosity material is used.

Folds may occur where the materials do not mix properly or where one material has started to set before the other is placed (when using a two- viscosity technique). Keywords: pVS, air- dried.

→ Van Noort r. Introduction to Dental Materials (4th ed.). elsevier, edinburgh; 203.

ZOe cements have a number of properties which facilitate their use as dental material. primarily, eugenol is thought to leach out from the material and into the surrounding dentine where it is said to have an obtundent or sedative effect upon the dentino- pulpal complex. Its mode of action is primarily attributed to its inhibition of capsaicin receptors. The material is generally supplied as a powder and liquid which has a relatively quick setting time once mixed. The material has historically been used as a lining or base material in deep cavities, as well as a root canal sealer. The material can have antimicrobial properties and has been shown to have good sealability when placed in adequate thickness. However, these would be secondary benefits in this scenario.

evidence exists to show that dentine bond strengths are negatively affected by ZOe materials. As such, their use should be avoided, or further surface preparation will be required where future adhesive restorations are to be placed. Non-e ugenol- containing zinc oxide root canal sealers are available to overcome this issue when restoring the root- treated tooth.

New tricalcium silicate-b ased restorative materials (e.g. Biodentine^™) have a growing wealth of evidence to support their use over ZOe in these clinical situations. However, these materials are more expensive and are yet to be routinely adopted into this clinical scenario.

Keywords: deep amalgam restoration, shooting pain, ZOe.

→ Koch T, peutzfeldt A, Malinovskii V, Flury S, Häner r, Lussi A. Temporary zinc oxide- eugenol cement: eugenol quantity in dentin and bond strength of resin composite. European Journal of Oral Sciences. 203;2:363– 9.

An attractive feature of GIC is that it can be placed in bulk and is less technique- sensitive than composite resin. Moisture control should still be maintained, as contamination with blood or saliva can reduce the bond strength.

The use of a conditioning agent on teeth prior to placement of GIC has been demonstrated to improve the bond strength, but the evidence is not conclusive. The main purpose of the conditioner is to remove debris from the surface and facilitate a clean surface for bonding. Strong agents that demineralize the tooth structure surface (such as citric acid or phosphoric acid) should be avoided, as they will reduce the quality of the ionic bond to apatite. polyacrylic acid 0% is the most commonly recommended conditioner for GICs.

Keywords: GIC, conditioning agent.

→ McCabe J, Walls A. Applied Dental Materials (9th ed.). Blackwell publishing Ltd, Oxford; 2008.