From the Research
The purpose of an outline bevel in a Class II cavity preparation is to increase the surface area for bonding, improve aesthetics, and prevent microleakage, and it should be created with a flame-shaped diamond bur at a 45-degree angle to the external tooth surface, approximately 0.5 to 1 mm wide along the gingival floor and facial/lingual walls of the proximal box, as supported by the most recent study 1. When outlining a bevel in a class II cavity, focus on the gingival floor and facial/lingual walls of the proximal box.
- Begin by using a flame-shaped diamond bur at a 45-degree angle to the external tooth surface.
- Create a shallow bevel approximately 0.5 to 1 mm wide along the gingival floor.
- Extend this bevel to the facial and lingual walls of the proximal box, maintaining the same width and angle.
- Do not place a bevel on the occlusal surface or axial wall of the preparation.
- Ensure the bevel is uniform and smooth to promote better marginal adaptation of the restoration. This beveling technique increases the surface area for bonding, improves the aesthetics of the restoration by creating a gradual transition between tooth and restorative material, and helps to prevent microleakage, as shown in a study evaluating marginal leakage of different restorative materials 2. Be cautious not to over-extend the bevel, as this can weaken the enamel margin and compromise the restoration's longevity, and in cases where the gingival margin is in dentin, a mini-bevel or no bevel may be more appropriate to preserve tooth structure, as suggested by a study on the effect of internal bevel on marginal leakage 3. However, the most recent study 1 found that bevel preparation failed to improve margin quality in large Class II composite restorations and is no longer recommended, but undermined enamel should be removed to prevent enamel fractures. Therefore, the decision to use a bevel should be made on a case-by-case basis, considering the specific needs of the patient and the tooth being restored, and the technique should be performed with caution and attention to detail to avoid compromising the restoration's longevity, as supported by a study on the preparation of enamel margin beveling in proximal cavities 4.