Effect of three types of mouth rinses and human saliva on microhardness of packable and nanocomposite resins (In vitro study)

Abstract

Background: The purpose of this an in vitro study was to evaluate and compare the influence of three types ofmouth rinses (alcohol- containing, alcohol-free and chlorhexidine-containing mouth rinses) and human saliva onmicrohardness of two types of composite resins (packable and nanofilled composite).Materials and Methods: Total numbers of 64 specimens were prepared, using molds specially fabricated for this studyand divided according to type of composite resins used, into two groups: 32 specimens made from packable P60and 32 specimens made from Filtek Supreme XT nanocomposite. Then each 32 specimens subdivided into 4subgroups according to treatment solutions used (Listerine, oral-B, chlorhexidine containing mouth rinses and saliva).The specimens of each subgroup was immersed, after curing, in distilled water for 24hr at 37°C then subjected tomicrohardness measurement for baseline readings determination using Vickers microhardness tester. Then eachsubgroup was immersed in 20 ml of treatment solutions and incubated at 37°C for 24 hr and re-subjected tomicrohardness measurement. The change in hardness value was calculated for each sample. The resulting datawere statistically analyzed using ANOVA and t- test at 0.05 significance level.Results: The results revealed that, all mouth rinses tested decreased the hardness of both tested resin-composites andnon significant reduction in microhardness with saliva.Conclusion: Both alcohol-containing & alcohol-free mouth rinses cause, highly significant reduction in microhardnessof composite resins while saliva causes non significant reduction in microhardness. Chlorhexidine-contaianing mouthsrinses highly significant decrease the hardness of nanocomposite and significantly decrease the hardness ofpackable composite.