Efficacy of self-etching primer on sealing margins of Class II restorations

To evaluate sealing ability of different types of restorative-adhesive combinations and to correlate etch patterns with leakage scores.

56 molars were selected and divided randomly in four groups of 14 specimens each. A standardized adhesive Class II preparation with the cervical margin placed 1 mm below the CEJ and an occlusal reduction of 2 mm was performed. No bevels were utilized in the preparation. Four combinations of bonding system/restorative material were tested. Group 1: Excite (EX) in combination with Tetric Ceram (TC) as control; Group 2: Prompt-L-Pop (PP1) applied for 15 seconds in combination with TC; Group 3: Etch and Prime 3.0 in combination with Definite restorative material (EP); Group 4: Prompt-L-Pop (PP2) applied for 30 seconds in combination with TC. The bonding systems (Groups 1, 2 and 3) and all restorative materials were used following strictly manufacturers' instructions. The resin composite was applied following an incremental technique. Ten specimens of each group were processed for leakage test. The specimens were sectioned with a diamond saw in three different areas in mesial-distal direction. Two different operators evaluated the sections blindly for scoring leakage at cervical and occlusal margins. The highest score for the sections of each tooth area was selected for scoring and further statistical analysis. The results of the staining measurements were statistically evaluated using the Kruskal-Wallis non-parametric analysis of variance with Bonferroni alpha protection. The level of statistical significance was defined as P<0.05. The remaining four specimens of each group were kept in a 37% HCl solution for 48 hours to dissolve the dental structures and to observe the resin replica of the cavities by SEM.

EX showed less dye penetration at occlusal margins than the other three groups, while no statistically significant differences were found at the dentin margin. The SEM observations showed rougher and more uniform enamel etch pattern when phosphoric acid (EX) was applied than that obtained with self-etching adhesive systems. Resin tags and adhesive lateral branches were noted in all groups at the dentin site.