Effect of composite resin placement techniques on the microleakage of two self-etching dentin-bonding agents

Purpose: To evaluate microleakage of Class V resin-based composites (RBC) b onded with two self-etching dentin adhesive systems. Class V cavities were restored with either one or three increments of RBC to determine whether th e restorative method affected microleakage. Materials and Methods: 60 extra cted human premolars and molars were randomly assigned to 6 groups for bond ing with Clearfil Liner Bond 2V or Etch & Prime 3.0 or Prime & Bond NT. The latter, using a total-etch technique, was used as a control. Cavities were cut in both the buccal and lingual surfaces. Half of each preparation was in enamel and half was in cementum/dentin. The teeth were thermocycled and the restorations examined microscopically for leakage using Procion Brillia nt Red as a marker. SEM microphotographs were prepared from dye-labeled and non dye-labeled areas to illustrate the micromorphology of the systems. Re sults: None of the groups showed microleakage at the enamel margins. All gr oups showed microleakage at the gingival margins. At the gingival margin, t here was no significant difference between the groups irrespective of the b onding material (Kruskal-Wallis: ANOVA P = 0.2113). No significant differen ce was observed with each material when the bulk filling (one increment) te chnique was compared with the three-increment technique. SEM showed that th e self-etching materials produced a shallower depth of etch, and a less abu ndant resin tag complex than the material using a separate phosphoric acid gel. In dye-labeled areas, debonding was predominantly cohesive in resin.