The effect of thermocycling on microleakage of several commercially available composite Class V restorations in vitro

Microleakage is a major factor contributing to the occurrence of secondary carious lesions around composite restorations. This in vitro study investigated the effect of thermocycling on microleakage of several composite Class V restorations. One hundred twenty molars were randomly distributed into 6 groups of 20 teeth. Class V preparations were made in the buccal and lingual surfaces of each tooth and restored in bulk by use of 6 composites (Arabesk, Silux-Plus, Solitaire 2, Durafill VS, Charisma, and Renew) according to the manufacturers’ recommendations. The teeth were stored in distilled water at room temperature for 24 hours. The teeth in each group were divided randomly into 2 subgroups: (a) thermocycled for 500 cycles between 5° and 55°C with a dwell time of 30 seconds, (b) no thermocycling treatment. All restored teeth were immersed in 1% methylene blue dye for 4 hours and sectioned buccolingually with a diamond wheel. Dye penetration was scored by use of a stereomicroscope at original magnification ×4. The generalized linear models statistical analysis was used (α=.05). The preparation margins (enamel/dentin) and thermocycling had a significant effect on microleakage ( P=.0351, P