Effects of light curing method on resin composite adaptation to the enamel and dentin cavity wall

Purpose: This study aimed to evaluate the effects of light-curing method on the marginal seal and resin composite adaptation to the cavity wall, and the formation of enamel cracks around resin composite restorations. Materials and Methods: Cylindrical cavities were prepared on the buccal or lingual cervical region of human molars. The teeth were restored with Clearfil Liner Bond 2 V and filled with Clearfil Photo Bright or Palfique Estelite resin composite. The resins were cured with the conventional light-curing method (600 mW/cm for 60 s) or the slow-start curing method (270 mW/cm for 10 s+5-s interval+600 mW/cm for 50 s). After thermal cycling, the specimens were subjected to a dye penetration test with a caries detector. Results: Light curing with the slow-start curing method resulted in a complete dentin marginal seal with both Clearfil Photo Bright and Palfique Estelite resin composites. This method also resulted in significantly better cavity wall adaptation of both resin composites compared with that achieved by the conventional method (p<0.05). The conventional method resulted in a poor dentin marginal seal and poor wall adaptation of both resin composites. Enamel crack formation was observed in all specimens. Conclusion: The slow-start curing method improved the marginal sealing and resin composite adaptation to the cavity wall. However, enamel crack formation could not be avoided, even with the slow-start curing method. The dye penetration test using a caries detector can be used to evaluate resin composite adaptation to the cavity wall both in vitro and in vivo. (Asian Pac J Dent 2014; 14: 13-18.)