Shrinkage vectors of a flowable composite in artificial cavity models with different boundary conditions: Ceramic and Teflon

• Published in: Journal of the mechanical behavior of biomedical materials Vol. 77; pp. 414 - 421
• Main Authors: Kaisarly, Dalia, El Gezawi, Moataz, Xu, Xiaohui, Rösch, Peter, Kunzelmann, Karl-Heinz
• Format: Journal Article
• Language: English
• Published: Netherlands 01.01.2018
• Subjects: Acrylic Resins - chemistry; Biocompatible Materials - chemistry; Bisphenol A-Glycidyl Methacrylate - chemistry; Ceramics - chemistry; Composite Resins - chemistry; Dental Bonding; Dental Caries; Dental Enamel; Dental Restoration, Permanent - methods; Dentin - chemistry; Dentin-Bonding Agents; Finite Element Analysis; Humans; Materials Testing; Polymerization; Polytetrafluoroethylene - chemistry; Polyurethanes - chemistry; Resin Cements; X-Ray Microtomography; Teflon; Boundary conditions; Ceramic; Shrinkage vectors; Flowable composite; Medical image registration
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2017.10.004

Polymerization shrinkage of dental resin composites leads to stress build-up at the tooth-restoration interface that predisposes the restoration to debonding. In contrast to the heterogeneity of enamel and dentin, this study investigated the effect of boundary conditions in artificial cavity models such as ceramic and Teflon. Ceramic serves as a homogenous substrate that provides optimal bonding conditions, which we presented in the form of etched and silanized ceramic in addition to an etched, silanized and bonded ceramic cavity. In contrast, the Teflon cavity presented a non-adhesive boundary condition that provided an exaggerated condition of poor bonding as in the case of contamination during the application procedure or a poor bonding substrate such as sclerotic or deep dentin. The greatest 3D shrinkage vectors and movement in the axial direction were observed in the ceramic cavity with the bonding agent followed by the silanized ceramic cavity, and smallest shrinkage vectors and axial movements were observed in the Teflon cavity. The shrinkage vectors in the ceramic cavities exhibited downward movement toward the cavity bottom with great downward shrinkage of the free surface. The shrinkage vectors in the Teflon cavity pointed towards the center of the restoration with lateral movement greater at one side denoting the site of first detachment from the cavity walls. These results proved that the boundary conditions, in terms of bonding substrates, significantly influenced the shrinkage direction.