Abstract
The contraction stress generated during the photopolymerization of resin dental composites is the major disadvantage. The water sorption in the oral environment should counteract the contraction stress. The purpose was to evaluate the influence of the water sorption of composite materials on polymerization shrinkage stress generated at the restoration-tooth interface. The following materials were tested: Filtek Ultimate, Gradia Direct LoFlo, Heliomolar Flow, Tetric EvoCeram, Tetric EvoCeram Bulk Fill, Tetric EvoFlow, Tetric EvoFlow Bulk Fill, X-tra Base, Venus BulkFil, and Ceram.X One. The shrinkage stress was measured immediately after curing and after: 0.5 h, 24 h, 72 h, 96 h, 168 h, 240 h, 336 h, 504 h, 672 h, and 1344 h by means of photoelastic study. Moreover, water sorption and solubility were evaluated. Material samples were weighted on scale in time intervals to measure the water absorbency and the dynamic of this process. The tested materials during polymerization generated shrinkage stresses ranging from 6.3 MPa to 12.5 MPa. Upon water conditioning (56 days), the decrease in shrinkage strain (not less than 48%) was observed. The decrease in value stress in time is material-dependent.
Highlights
An integral feature of all currently available resin-based restorative materials is polymerization shrinkage [1]
The dental materials are constantly immersed in saliva, and sorption and solubility occur [5,6]
The purpose of this study was to evaluate the influence of water sorption of composite materials on polymerization shrinkage stress generated at the restoration-tooth interface
Summary
An integral feature of all currently available resin-based restorative materials is polymerization shrinkage [1]. Teeth undergo consistent chewing and biting loads. During restorative procedures new additional stress appears in the tooth structure, increasing the overall stress levels [2]. As a result of deformation or even cracks in the tooth structure, the damage of the adhesive bond, secondary caries, post-operative sensitivity, and marginal discoloration might be found [3,4]. The dental materials are constantly immersed in saliva, and sorption and solubility occur [5,6]. The water diffuses into the material and causes a gradual expansion and volume increase
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