Effect of curing unit type of composite and gingival margin location on the cervical marginal integrity of bulk - filled class II resin composite restorations

Abstract

The aim of the present study was to evaluate the effect of the type of light-curing unit, composite resin type and the location of the gingival margin on gap formation in Cl II cavities restored using the bulk-fill technique with a silorane-based and a methacrylate-based composite resin and light-cured with QTH and LED light-curing units. Materials and methods: Sixty third molars were selected and two Cl II cavities were prepared on each tooth, one at the mesial aspect 1 mm coronal to the CEJ and the other one at the distal aspect 1 mm apical to the CEJ. The teeth were assigned to 4 groups. In group A, the cavities were restored using the bulk-fill technique with Filtek P90 composite resin and its adhesive system, followed by light-curing with QTH light-curing unit. The cavities in group B were restored in a manner similar to that in group A but light-cured with an LED light-curing unit. In group C, the cavities were restored using the bulk-fill technique with X-tra Fil composite resin and Clearfil SE Bond adhesive system and light-cured with a QTH light-curing unit. The cavities in group D were restored in a manner similar to that in group C but light-cured with an LED light-curing unit. The gaps were evaluated under a stereomicroscope at 60. Data were analyzed with GLM test. In case of statistical significance (P<0.05), post hoc Bonferroni test was used for further analyses. Results: The type of the light-curing unit had no effect on gap formation. However, the results were significant in relation to the composite resin type and margin location (P<0.001). The cumulative effects of light-curing unitgingival margin and light-curing unitcomposite resin type were not significant; however, the cumulative effect of composite rein typegingival margin was significant (P=0.04). Conclusion: X-tra Fil composite resin exhibited smaller gaps compared with Filtek P90 composite resin with both QTH and LED light-curing units. Both composite resins exhibited smaller gaps at enamel margins compared to dentinal margins