The effect of light-curing modes on the microleakage of cervical resin composite restorations

Abstract 

Objective. This study investigated the effect of light-curing modes on the microleakage of cervical resin composite restorations.

Methods. Eighty wedge-shaped cervical cavities, C-factor approximately 1.3, were prepared on the labial surface of bovine incisors. The cavities were treated with a two-step experimental self-etching primer adhesive system containing an antibacterial monomer (ABF), according to the manufacturer's instructions, and filled with a single increment of a hybrid resin composite. The restorations were allocated randomly into four groups of 20: Group 1—the restorations were light-cured for 40 s with a conventional light-curing unit (New Light VL-II); Group 2—the restorations were cured with Candelux using a two-step mode; Group 3—the restorations were cured with Astralis 7 using a ramping mode; Group 4—the restorations were light-cured for 3 s with a plasma arc light-curing unit (Wave Light). Half of the specimens from each group were subjected to thermocycling (5–60 °C, 15 s dwell time, 5000 cycles) prior to immersion in 0.5% basic fuchsin. The teeth were sectioned and the degrees of dye penetration were scored. The data were analyzed with either the Kruskal–Wallis test or the Mann–Whitney U-test (p<0.05).

Results. No significant differences were found in the microleakage scores among the light-curing modes used. The restorations tended to display more microleakage when they were subjected to thermocycling, but the differences were not statistically significant.

Conclusions. These findings suggest that light-curing modes may have no effect on the microleakage of cervical cavities with a small C-factor, as is the case in this study.

Keywords:  Microleakage, Cervical lesions, Light-curing modes, Rate of polymerization, Polymerization shrinkage stress