Microhardness and cervical microleakage of healthy and periodontally involved dentin at class II cavities restored with conventional and bulk-fill resin composites

Aims: The purpose of this in-vitro research was to compare microhardness and cervical microleakage of healthy and periodontally involved dentin after restoration with conventional and bulk-fill composites. Methods: For microhardness test, 20 human molars were collected (10 healthy and 10 for periodontal reasons). Dentinal disks from cemento-enamel junction were prepared. Each specimen received 9 indentations (3 for each superficial, median and deep dentin) and an average of them was recorded as the Vickers hardness number (VHN) of each area. For microleakage test, 20 healthy teeth and 20 extracted for the periodontal disease were collect-every tooth. The samples of each group were randomly allocated to two subgroups of 10 and restored as follows: in the experimental group, the cavities were filled by a 4-mm layer of Tetric N-Ceram bulk-fill resin composite (BRC). In the control group, the conventional resin composite (Tetric N-Ceram) was inserted incrementally and then light cured. After 1000 cycles of thermocycling, cervical microleakage was evaluated by dye extraction technique. Data were submitted to ANOVA, t-test, and Mann-Whitney U test (a = 0.05). Results: VHN values of healthy dentin at all depths were more than periodontally involved dentin. The most microleakage was seen in periodontally involved teeth filled with conventional composite, but there were no significant differences between different groups. Conclusions: Although periodontal disease had a significant effect on the reduction of VHN, but no significant effect was observed on the cervical microleakage after using different resin composites.