Effect of light-curing units on gap formation and microleakage of class II composite restorations

ABSTRACT

Aim: This in vitro study evaluated gap width formation and marginal microleakage in Class IIcomposite restorations light-cured with three different light-curing units. Methods: Standardizedcavities in the proximal surfaces of 36 human third molars were made with margins located belowthe cementoenamel junction. Cavities were restored with Filtek P60 (3M ESPE), inserted with aphotocondenser tip and light-cured with three different methods: GI - Optilux401 (halogen); GII –ColtoluxLED (LED) and GIII –UltraLumeLED5 (LED). After finishing the restorations, teeth weresubjected to a thermal cycling regimen of 500 cycles (5oC ± 2oC and 55oC ± 2oC), totalizing 500cycles. Thereafter, the teeth were sectioned in a buccolingual direction and in the center of therestorations. Half of the specimens (18) were used to evaluate marginal microleakage, by measuringof dye penetration in cross-sectioned specimens, and the other half was used to analyzed the gapformation width by SEM observations (1000X). Data were submitted to Kruskal-Wallis (α=0.05).Results: The mean values of gap width (μm) were GI 3.28±3.34; GII 1.48±1.89 and GIII3.11±3.45, and microleakage was not affected by the light-curing units. Conclusions: Therewere no differences between the light-curing methods in gap formation and marginal microleakage.