Influence of location of the gingival margin on the microleakage and internal voids of nanocomposites.

AIM The aim of this in vitro study was to investigate the cervical microleakage and internal voids of nanocomposites comparing them with a hybrid composite in Class II restorations with the margins located coronal and apical to the cementoenamel junction (CEJ). METHODS AND MATERIALS Standardized MOD cavities (one cervical margin located in dentin, one in enamel) were prepared in 40 extracted human molars and divided into four groups according to the composite used to restore them (n=10/group). Group 1: Adper Single Bond2/Filtek Supreme XT; Group 2: Excite/Tetric EvoCeram; Group 3: Prime & BondNT/Ceram X; and Group 4 (control) Adper Single Bond2/Filtek Z250. Groups were further divided into subgroups A and B. The "A" subgroups represent the level of the location of the cervial margin at 1 mm coronal to the CEJ, and the "B" subgroups represent the level of the cervical margin located 1 mm apical to the CEJ. After restoration of the cavities with nanocomposites, thermocycling, and immersion in 0.5% basic fuchsin, the dye penetration and internal voids were evaluated under a stereomicroscope. Data were analyzed with the Mann-Whitney U and Kruskal-Wallis tests with the Bonferroni correction for microleakage and with the Chi-square test for internal voids (p<0.05). RESULTS The microleakage in the A subgroups was statistically significantly lower then B subgroups (p<0.05). No statistically significant difference was observed in terms of interface, cervical, and occlusal voids for all groups (p>0.05). No significant difference was observed between each group for three voids in all groups (p>0.05). CONCLUSION The location of the gingival margin affects the microleakage of nanocomposites but has no significant affect on the internal voids. CLINICAL SIGNIFICANCE Gingival margin located 1 mm coronal to the CEJ provided a reduction in cervical microleakage in nanocomposite restorations.