OBJECTIVES The present study examines the influence of cavity type, and size of composite restorations on cuspal flexure due to polymerization shrinkage. METHODS Thirty healthy premolars were selected and divided into two experimental groups. Group 1: Mesial, mesio-distal, and MOD cavities were successively prepared in each tooth by means of the SONICSYS approx system (KaVo) using a n 2 (smal...

Low-shrinkage resin composites are in the focus of research in posterior resin composite restoratives. The aim of the study was to examine the polymerization shrinkage stress of new composites (Venus Diamond/ Heraeus Kulzer; SDR/DENTSPLY) and an experimental low-shrinkage resin composite (Ormocer/VOCO) in comparison to established low-shrinkage resin composites (Filtek Silorane/ 3M ESPE; els/Sa...

Current methods to determine debonding/leakage at the tooth-composite interface are qualitative or semi-quantitative. Our previous work introduced a 3D imaging technique to determine and visualize leakage and its distribution at the interface of cavity wall and composite restoration in model cavities. In this study, an automated program was developed to quantify leakage in terms of area and vol...

The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different compo...

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 we...

Advances in the mechanical properties of composite resins have allowed for their use in posterior teeth. Conventional resins have several problems associated with polymerization shrinkage stress. The development of "bulk-fill" resins has allowed for their use in single increments up to depths of 4 mm, with very low polymerization shrinkage stress. Nevertheless, differences in anatomy and the de...

merization of dental composite materials during lightcuring is a leading cause of adhesive restoration failure, resulting in postoperative sensitivity, marginal staining, and recurrent caries.1 This polymerization contraction shrinkage creates stresses as high as 13 MPa between the composite material and tooth interface2 (1 MPa = 145 psi). This stress can exceed the tensile strength of the enam...

The kidney medulla is physiologically exposed to variations in extracellular osmolality. In response to hypertonic cell shrinkage, cells of the rat kidney medullary thick ascending limb of Henle's loop undergo p38 kinase-dependent regulatory volume increase (RVI). In the present study, we investigated the role of actin cytoskeleton reorganization in this process. Addition of hyperosmotic NaCl o...

Polymer networks that can serve as model systems for dental applications were prepared by photopolymerizations of 1,1,1-trimethylolpropane triacrylate, 1,1,1-trimethylolpropane trimethacrylate, 1,1,1-trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, Photomer 2028 and Photomer 3015. The UV polymerizations were initiated by 2,2-dimethoxy-2-pheny...