Chapter 1

Better results may be anticipated when composites are prescribed in combination with strategically placedrestorations having a metal or ceramic occlusal surface. By restoring adjacent teeth with more wearresistant occlusal surfaces, the composite may be protected from high occlusal forces, but its successrate has not been reporte

Some patients have multiple posterior teeth with severely worn occlusal surfaces. The temptation to restore them only with composite should be tempered by the catastrophically high failurerate of 52% reported at 3 years for a micro!lled composite when used either directly or indirectly.

Wang’s systematic review of all-ceramic crowns reported similar results with a 5-year fracture rate of 4.4%. There was a significantly higher fracture rate for crowns on molar teeth compared with premolars (8.1% c.f. 3.0%) and crowns on posterior teeth compared with anteriors (5.4% c.f. 3.0%).

One disadvantage of indirect composite restorations with an inlay component is that they often require additional tooth removal to prepare a cavity free from undercut.

to enhance the composite’s physical properties by heating to 120 °C and to reduce problems from polymerisation shrinkage

To protect ceramic restorations from bruxism, a soft or hard occlusal splint may be advisable; however, it is not known to what extent this approach may improve restoration longevity, and it relies of course on patient compliance

Failures were related to fractures/chipping (4%), followed by endodontic complications (3%), secondary caries (1%) and debonding (1%). More failures were reported in molars and root-treated teeth

Clinical wisdom recommends ceramic onlays be made in thicker section (2 mm occlusally) to prevent fracture due to the brittle nature of the material.

For bruxists we recommend at least 1 mm occlusal thickness to reduce the risk of a posterior onlay wearing away and perforating

These restorations are sometimes called “shims” when used on posterior teeth without a retentive inlay component or on anterior teeth.

Advances in composite technology are promising and may eventually make direct composite at least as good aesthetically as ceramic veneers. Clearly, long-term data are needed to inform material choice and technique

In addition, although both types of veneer had transient post-operative sensitivity, there was a non-significant trend to a higher incidence with composite veneers. So, doubts remain clinically with indirect composite veneers over possible higher levels of pulpal sensitivity following veneer placement and their longerterm wear and aesthetic characteristics. They do however provide a cost-effective and modifiable option to the clinician. Furthermore, direct composite veneers require minimal tooth preparation.

Often veneers are provided for teeth with existing fillings. Some authorities suggest bonding to the existing fillings as it is conservative of tooth tissue, but other studies report higherfailure rates. Failure may be due to resin bonding to the existing filling being compromised by water sorption and lack of availability of reactive sites in the resin of the old composite.Furthermore, preparation of an existing composite filling will expose un-silinated filler particles whichcan be difficult to bond to. For longer-term stability, it may be prudent to replace the fillingshortly before the preparation or immediately after the veneer is fitted. These approaches also help to ensure that the filling is properly bonded to the underlying tooth. An existing but satisfactory composite may also be conditioned using airborne particle abrasion.

Often veneers are provided for teeth with existing fillings. Some authorities suggest bonding to the existing fillings as it is conservative of tooth tissue, but other studies report higherfailure rates. Failure may be due to resin bonding to the existing filling being compromised by water sorption and lack of availability of reactive sites in the resin of the old composite.Furthermore, preparation of an existing composite filling will expose un-silinated filler particles whichcan be difficult to bond to. For longer-term stability, it may be prudent to replace the fillingshortly before the preparation or immediately after the veneer is fitted. These approaches also help to ensure that the filling is properly bonded to the underlying tooth. An existing but satisfactory composite may also be conditioned using airborne particle abrasion.

Reasons for veneer failure include debonding, fracture, marginal discoloration and defects, especially when bonded to dentine or existing restorations. Failure may also result from pulpal involvement following tooth preparation or from subsequent microleakage or caries.

There are three main types of veneer determined by material: feldspathic ceramic, non-feldspathic (generally high-strength ceramics) and composite (direct and indirect).

Veneers comprise a layer of tooth-colored material attached to the surface of a tooth. They are
frequently used to improve aesthetics by modifying the color, shape or position of a tooth.

adhesively retained restorations are often the only viable conservative option where a tooth has already lost a significant amount of tissue and where removal of further tissue to incorporate retentive features (e.g. grooves and boxes) could render it unrestorable. Adhesive technology may also be employed in the placement of posts in endodontically treated teeth.

This is an important consideration because conventional cements are inherently brittle and, like a piece of crisp bread, will fail at relatively low tensile stress. Despite the adhesive properties of glass ionomers and zinc polycarboxylates, they are still too brittle to be used with tooth preparations which are short or too tapered

A conventional restoration is distinguished by needing a tooth preparation so it can be luted with conventional cement (e.g. zinc phosphate, zinc polycarboxylate and glass ionomer).