In Vitro Study On Effect Of Different Filling Modes In Microleakage Of Composite Resins

Objective: Comprehensive assessment of clinical operational factors on theformation of the microleakage of composite resin, and observe and evaluate the effectof the composite resin filling dentin.Methods:72vitro premolars were divided into12groups, each group of sixspecimens. They were filled by3kinds of composite resins (universal compositeresin, liquidity composite resin, compomer) in2different ways of filling (horizontallayering and vertical layering) and2different ways of light-curing (constantlight-curing and gradually light-curing). After300times of hot and cold watertemperature cycles, all specimens were immersed in a0.5%fuchsin solution at roomtemperature for24hours, and then each tooth was sectioned into3pieces, each groupof18pieces. We observed the degree of dye penetration along the profile (from thebuccal to lingual) under the stereomicroscope. Using Chi-square test for R×C listinformation on the number of samples of each group classification, and calculate theaverage of the microleakage, analysis with multivariate analysis of variance, pairwisecomparison with SNK method.Results:1. Chi-square test for R×C list information:①Depends on thedifferent filling methods, there was no significant statistically difference in fivegroups, except in compomer+gradually light-curing group there was significantstatistically difference (P<0.05).②Depends on the different light-curing methods,there was no significant statistically difference in four groups, except in liquiditycomposite resin+horizontal layering group and in compomer+vertical layering,there was significant statistically difference (P<0.05).③There was significantlystatistically difference among three kinds of different materials within anycombination of filling and light-curing methods (P<0.05).2. Multi-factor analysis ofvariance:①Univariate analysis: Factor effect of the composite resin wassignificantly (P <0.05), there were significant differences on the count ofmicroleakage of different composite resin. Microleakage mean values in ascendingorder were as follows: universal composite resin<compomer<liquidity composite resin. Factor effect of the filling method was significantly (P <0.05), there aresignificant differences on the count of microleakage of different filling methods.Microleakage mean values in ascending order were as follows: vertical layering<horizontal layering. But factor effect of the light-curing method was not significantly(P>0.05), there was no significant difference on the count of microleakage ofdifferent light-curing methods.②Interaction of the first level constitute by twofactors: There was interaction effect between the types of composite resin and fillingways. The smallest microleakage mean values is in the compomer+vertical layeringgroup, the largest one is in the compomer+horizontal layering group. There was nointeraction effect between the types of composite resin and light-curing ways, andeither between filling ways and light-curing ways.③Interaction of the second levelconstitute by three factors: There was interaction effect among the types of compositeresin, filling ways and light-curing ways. The smallest microleakage mean values isin the compomer+vertical layering group+gradually light-curing group, the largestone is in the compomer+horizontal layering group+gradually light-curing group.Conclusions:1. Vertical layering method is more conducive to reduce themicroleakage of composite resin than horizontal layering method;2. There was nosignificant difference between horizontal layering and vertical layering.3.Microleakage of universal composite resin is the least, followed by compomer, andthe most one is liquidity composite resin.4. Type of composite resin, layering mode,light curing methods are three factors, which exist the interactive relationship on theoccurrence of microleakage. For the universal composite resin, vertical filling method+constant light-curing mode can minimize the microleakage; For the liquiditycomposite resin, horizontal layering+constant light-curing mode can minimize themicroleakage; For the compomer, vertical layering+gradually light-curing mode canminimize the microleakage.