Effect of different polymerization methods on composite microleakage.

PURPOSE: To evaluate the microleakage of a condensable resin composite using a microhybrid flowable composite as a liner, cured with four different methods of polymerization.

METHODS: 40 freshly extracted caries-free human premolars and molars were used. MO/DO Class II standardized preparations were performed with the gingival margin placed 1 mm above the CEJ. Teeth were randomly divided into four groups. Group 1 (control group): conventional mode (Elipar Highlight), Group 2: step mode (Elipar Highlight), Group 3: ramp mode (Elipar Trilight) and Group 4: pulse mode (VIP). Preparations were etched with 32% phosphoric acid (Uni-Etch) and an adhesive system (One-Step) was used according to the manufacturer's instructions. Teeth were then restored using a 1 mm layer of flowable composite (A2 AEliteflo LV) on the gingival and pulpal floor and condensable composite (Pyramid A2 Dentin and A1 Enamel) in 2 mm increments. Teeth were thermocycled x500 between 5 degrees C and 55 degrees C with a dwell of 30 seconds and then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the gingival margin under a stereomicroscope at x30 magnification. Dye penetration was scored using an ordinal scoring system as 0: no penetration; 1: enamel penetration; 2: dentin penetration.

RESULTS: A Mann-Whitney U Test revealed a statistically significant difference between Group 1 with Groups 2, 3 and 4 (P < 0.001). Group 1 yielded the most microleakage. No statistically significant difference was noted between Groups 2, 3 and 4.