광중합 복합레진 수복시 여러 광조사 방법에 따른 미세변연누출에 관한 연구

MICROLEAKAGE OF CL V COMPOSITE RESTORATIONS USING VARIOUS LIGHT CURING METHODS

The purpose of this in vitro study was to evaluate the microleakage of 5 curing methods in class V composite restorations which are composed of two-step light curing, pulse-delay cure, low curing-light intensity, moderate curing-light intensity and high curing-light intensity. In this study, class V cavities were prepared on buccal and lingual surfaces of 50 extracted human upper or lower molars on cementum margin. Single Bond adhesive and Z-100 shade A2 were applied for each group following the manufacture's instruction. The experimental teeth were randomly divided into 5 groups of 10 samples (20 surfaces) each. Group 1: two-step light curing; Group 2: pulse-delay cure; Group 3: low curing-light intensity; Group 4: moderate curing-light intensity; Group 5: high curing-light intensity. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen was then observed with a stereomicroscope at ${\times}20$. The composite resin/tooth interfaces were examined under Scanning Electron Microscopy. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA and Dunn's Method. The results of this study were as follows. 1. In all groups, the leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. No group in this study showed significant differences in leakage values at both the enamel and the dentin margins(P<0.05). 3. In all groups, the gaps seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 4. The gaps in this study showed significant differences and two-step light-curing and low curing-light intensity produced significant less gap than high curing-light intensity(P<0.05).