RESUMEN
Introduction: microleakage of gingival floor in class II composite resin restorations is a major clinical problem. The aim of this study was evaluation of the effects of light conducting intrawedges [LCIW] in decreasing gingival microleakage 1 millimeter above CEJ in class II composite resin restorations
Materials and Methods: sixty maxillary first molars were randomly divided into six groups of ten. Proximal slot cavities with gingival floor one millimeter upper to CEJ were prepared. They were filled with Brilliant composite [A3] by six different method: A: Unfilled resin [UR] + One bulk placement D: URt-Incremental placement B: UR+Light Conducting Intrawedges [LCIW]+One bulk placement E: UR + LCIW + Incremental placement C: DBA + LCIW + One bulk placement F: DBA+LCIW+Incremental placement An etched and silanated bioglass cylinder [2mm diameter] was used as LCIW. After 2500 times of thermocycling [5oc-55oc], Samples were stained and molded in epoxy resin. Mesiodistal sections were prepared one in central and the other in the most lateral part [buccal or lingual] of gingival floor. Dye penetration was determined using a stereomicroscope. The statistical analysis was done by one-way ANOVA and Duncan's test
Results: the mean dye penetration of central and lateral sections was the least in group C [0.8 and 1 respectively] and then group F [1.2 and 1.3]. this shows that because LCIW has inserted in cavity after curing of 1mm layer in gingival floor in groups E and F, their effect in decreasing the microleakage is less [compared with group C]
Conclusion: LCIW in one bulk placement of composite resin restorations can minimize the associated difficulties
RESUMEN
Introduction: the reaction of polymerization can be controlled by the light exposure pattern and the temperature. The purpose of this study was to evaluate the effect of different light exposure patterns and composite temperatures on microleakage of light cured composite resin restorations
Materials and Methods: in this interventional study, class V cavities were prepared on 200 extracted human molars. Then the teeth were randomly divided into four main groups according to different light exposure patterns of High Intensity Program [HIP], Low Intensity program [LOP], Puls Program [PUL] and Suggested Progressive Program [SUP] and 5 subgroups according to different temperatures of composite during curing [5oc, 20oc, 35oc, 50oc and 65oc]. After thermocycling and dye penetration, measurement of microleakage was done using a stereomicroscope. The data were analysed using SPSS software [ANOVA]
Results: ANOVA showed that both in enamel and dentinal margins, a significant decrease in microleakage has occurred in SUP group. Microleakage in enamel and dentinal margins was significantly higher in HIP group than the other groups. No significant difference was observed in the rate of microleakage among the 5 subgroups with different temperatures
Conclusion: SUP light curing pattern could be considered for improving composite resin restorations as a superior light exposure pattern due to its ability in Polymerization control, reducing polymerization shrinkage stress and microleakage. Prewarming of the composites is a practical and easy way to improve composite properties for dental restorations