Investigation into class II dye penetration below the dej

Objectives: To investigate variables involved in class II dye penetration.

Methods: 40 Class II restorations were prepared in recently extracted human molars to 1 mm below the dej. Simplicity adhesive was applied to all restorations. A 1mm layer of Titan flowable was inserted and light-activated, followed by insertion of Z100 composite in 2 mm increments, each light-activated for ten seconds. The following groups were examined: 1. Flowable light-activated for ten seconds, restoration proximal margins polished with discs, 2. Flowable light-activated for ten seconds, proximal margins not finished, 3. flowable light-activated for forty seconds, proximal margins finished with discs, 4. flowable light-activated ten seconds, proximal margins polished with discs and re-sealed with adhesive. Dye penetration was measured as fraction of pulpal floor restoration depth with the full length of the floor normalized to the integer 1.

Results: Group 1: 0.48 (.27), Group 2: 0.05 (.12), Group 3: 0.29 (.35), Group 4: 0(0). Group 2 and 4 exhibited appreciably less dye penetration than did Groups 1 and 3.

Conclusions: Historically restorations in class II dye penetration experiments are always polished but in actual practice it is rarely feasible to do so. When the class II restorations were not polished they exhibited very little dye penetration. When the restorations were sealed after polishing no dye penetration was seen at all. When the flowable was light-activated for 40 seconds, dye penetration was less than when flowable was light-activated for 10 seconds, but not significantly so. Longer activation periods appear to improve resistance to dye penetration. Re-applying the adhesive as a sealer following polishing was effective in completely eliminating dye penetration. The polishing process itself appears to be largely the cause of dye penetration in class II restorations yet if access exists to polish restorations, then access also exists to re-seal restorations.