1급 와동에서 상아질과 복합레진의 결합강도에 대한 중합방법의 효과

Abstract

Despite the different light sources and polymerization techniques developed to eliminate polymerization shrinkage of composite resin, it still remains a problem. The polymerization shrinkage of composite resin creates contraction stresses that can distrupt the bond to preparation walls and margins. This in vitro study was designed to compare the effect of different curing modes on resin/dentin bond strength in Class I cavities. Occlusal enamel was removed to expose a flat dentin surface and twenty box-shaped Class I cavities were prepared in dentin (4 ㎜ wide, 3 ㎜ long, 2 ㎜ deep). Single Bond (3M Dental product) was applied and Z 250 (A2 shade) was inserted using bulk technique. The composite was light-cured using one of four techniques; pulse delay (PD group), soft-start (SS group), pulse cure (PC group) and standard continuous cure (CC group). The light-curing unit that could adjust time and intensity (VIP, Bisco Dental product) was selected and the light energy density for all curing modes was fixed at 16 J/㎠. After storage for 24 hours, specimens were sectioned into beams with a rectangular cross-sectional area of approximately 1 ㎟. Microtensile bond strength (μTBS) test was performed using a universal testing machine (EZ Test, Shimadzu Co.). The results were analyzed using one-way ANOVA and Tukey's test at significance level 0.05. The results of this study were as follows; 1. The μTBS of PD group (18.7 ± 8.08 MPa) was significantly higher than that of PC group (13.9 ± 7.26 MPa) and CC group (14.1 ± 5.60 MPa) (p < 0.05). 2. The μTBS of SS group (17.0 ± 5.09 MPa) was higer than that of PC group and CC group , but there was not significantly different (p > 0.05). Within the limitations of this in vitro study, modification of curing modes such as pulse delay and soft start polymerization can improve resin/dentin bond strength in Class I cavities by controlling polymerization velocity of composite resin.