Subir Banerji and Shamir B. Mehta
Concerns with the use of dental amalgam have paved the way for alternative dental materials for the direct restoration of posterior teeth.1 Resin composite is one such material. The advantages and disadvantages of resin composite in this application have been summarised in Table 5.5.1.
The indications of directly bonded posterior composite restorations include the following:
- The treatment of small to moderately sized restorations
- Where aesthetics are of prime importance
- Where an occlusal prescription is being developed or monitored in cases of tooth wear.
However, caution is advised where:
- The centric occlusal stops are likely to be placed on the restorative material, due to concerns with material wear
- The patient exhibits signs of excessive occlusal wear or loading
- It is not possible to achieve good moisture control
- The patient is allergic or sensitive to resin-based materials
- The patient has a poor standard of oral hygiene/plaque control with high caries predisposition
- The gingival cavosurface margin is not located on intact enamel, as the bonding of resin composite to dentine is less effective.
Table 5.5.1 The merits and drawbacks of resin composite as a posterior restorative material
|Conservation of dental hard tissues||Post-operative sensitivity|
|Reduced thermal conductivity||Secondary caries|
|Potential for repair||Decreased wear resistance and bulk fracture|
|Adhesion to tooth tissue||Technique sensitivity|
|Lack of galvanic conduction||Water sorption|
Pre-operative shade selection must be accomplished (with the aid of a proprietary shade guide) prior to the application of rubber dam, as dehydration and isolation may alter shade. It is advisable to undertake shade selection following the completion of cavity preparation to enable you to gain a better insight into the colour variations that may be present in the dentinal layer. It is important to be aware that most available composite resin shade guides are based on acrylic materials (rather than the actual composite resin). Hence, it is prudent to compose a customised shade guide. With the availability of opaque shades, it is also possible to mask residual discoloration at the base of a cavity.
Pre-operative centric stops should be marked with articulating paper. Eccentric contacts should also be identified. Ideally, occlusal contacts should be maintained on tooth tissue where possible; if not, they should be reproduced in the anatomy of the restoration (when undertaking ‘conformative procedures’).
Complete moisture control is mandatory for clinical success with posterior resin composites, as outlined in Chapter 5.2.
For details about adhesive cavity preparation and matrix application for a posterior resin restoration, refer to Chapter 5.3. For some restorations, especially where they are in close proximity to the pulp chamber, there may be a need to consider the use of a base/liner. Commonly used materials include glass ionomer cements, auto-cured and flowable resins, as well as ‘bioactive dentine substitutes’.
The use of RMGICs