Relationship between proximal cavity design and recurrent caries

A total of 375 Class II restorations were divided into short, intermediate, and long groups according to occlusal-gingival length and its relationship to the contact area of adjacent teeth as determined radiographically. Recurrent caries at the gingival margin was studied during a 2-year period. Restorations with gingival margins ending occlusal to the contact area had a significantly higher rate of caries at all time intervals. Results suggested, in part, that the additional length of the restoration is not as critical as clearing the contact area.