The aim of the present study was to evaluate the effect of natural saliva contamination of dentin on the adaptation of composite resin restorations as well as the efficacy of various decontamination techniques. A total of 120 human molars and premolars were randomly distributed into 6 groups (n = 20). Standardized dentin cavities were prepared and restored with composite resin after 1 of 6 different surface treatments, which included a 2-step etch-and-rinse adhesive: 1, dentin etching, adhesive application following the manufacturer's instructions (control), light curing; 2, dentin etching, saliva contamination, air drying, adhesive application, light curing; 3, dentin etching, saliva contamination, water rinsing, air drying, adhesive application, light curing; 4, dentin etching, adhesive application, light curing, saliva contamination, air drying; 5, dentin etching, adhesive application, light curing, saliva contamination, water rinsing, air drying; or 6, dentin etching, adhesive application, light curing, saliva contamination, water rinsing, air drying, adhesive reapplication. The adaptation was evaluated at the top surface and at depths of 0.5 and 1.0 mm by measuring the length of the debonded margin and calculating its percentage relative to the cavity perimeter (%DM). The internal adaptation was evaluated by measuring the width of the maximum marginal gap (MMG). Inferior adaptation was observed after saliva contamination took place. Group 1 presented the most satisfactory adaptation at the top surface, whereas groups 4 and 5 had the highest %DM and greatest MMG at all surfaces (P < 0.05). The %DM and MMG values in groups 2, 3, and 6 were not significantly different from those of group 1 or each other. Saliva contamination after adhesive application (groups 4 and 5) resulted in deterioration of marginal and internal adaptation. Reapplication of the adhesive restored adaptation, as evidenced by the %DM and MMG values in group 6.
Keywords: adhesive; contamination; marginal adaption; microgap; saliva.