Class II caries are found on the proximal surfaces of posterior teeth. Due to inadequate oral hygiene, most lesions begin just gingival to the interproximal contact area. Restoration of these lesions include restoring defective occlusal surfaces under the concept of extension for prevention. However, if no occlusal defects exist, a conservative proximal box preparation may be indicated.
The occlusal outline form follows the same criteria as for a Class I: Remove all non-coalesced or defective pits and fissures developing an isthmus, buccal and lingual extensions, and dovetails as dictated by the tooth's anatomy. For extension for prevention, the proximal outline form dictates a cavosurface margin that is 0.5 mm from the adjacent tooth - buccally, lingually, and gingivally. This allows the patient to more easily clean and maintain all margins of the final restoration thus enhancing longevity.
