Objectives: One of the major concerns with composite restorations is the interfacial gap-formation in the restorative cavity. The purpose of this study was to evaluate the effect of polishing after one-day storage on the interfacial gap-formation in Class I restorations with self-etching adhesives and posterior composites (QuiXX + Xeno IV, Dentsply/Caulk (QX); P-60 + Adper Prompt L-Pop, 3M ESPE (P6); Premise + OptiBond Solo Plus Self-Etch Adhesive, Kerr (PM); Gradia Direct + G-Bond, GC (GD); Clearfil AP-X + Clearfil tri-S Bond, Kuraray (CF)).

Methods: Cylindrical Class I cavities were placed in molars, having diameter = 3.5 mm and depth = 1.5 mm. Restorative procedure were performed according to manufacturers’ instructions. Restored teeth were polished and then sectioned in a mediodistal direction through the center of the restoration immediately (IM) and after one-day storage (1-D). Then, the presence or absence of gaps around the restorations was measured at 14 points (each 0.5 mm apart) along the cavity restoration interface (N=10, total points measured = 140, Dent Mater 2006, in press). The number of interfacial gaps in each sample was totaled and expressed as the sum of each sample. The shear bond strength to dentin was measured with the same materials under same conditions. Statistical analyses were conducted by Mann-Whitney U-test (in sum of gaps for all ten samples, p<0.05) and t-test (for shear bond strength, p<0.05, N=10). t-test (in SBS, p<0.05, N=10).

Results: 

Conclusions: Delaying polishing for one-day resulted in improved interfacial gap-formation for Class I restorations of posterior composites and the shear bond strengths exhibited significant improvement.