Analysis of local shrinkage patterns of self-adhering and flowable composites using 3D digital image correlation

• Published in: Quintessence international (Berlin, Germany : 1985) Vol. 42; no. 9; p. 797
• Main Authors: Miletic, Vesna, Manojlovic, Dragica, Milosevic, Milos, Mitrovic, Nedad, Stankovic, Tatjana Savic, Maneski, Tasko
• Format: Journal Article
• Language: English
• Published: Germany 01.10.2011
• Subjects: Algorithms; Barium Compounds - chemistry; Composite Resins - chemistry; Curing Lights, Dental - classification; Dental Materials - chemistry; Glycerophosphates - chemistry; Humans; Image Processing, Computer-Assisted - methods; Imaging, Three-Dimensional - methods; Light-Curing of Dental Adhesives - methods; Materials Testing; Methacrylates - chemistry; Photography, Dental - methods; Polymerization; Silicon Dioxide - chemistry; Stress, Mechanical; Surface Properties; Time Factors; Viscosity
• ISSN: 1936-7163

To analyze local shrinkage patterns in terms of surface shrinkage strains and z-axis displacements in a novel self-adhering composite and a conventional flowable composite using three-dimensional digital image correlation. Seven samples of each material were prepared in cylindrical Teflon molds 5 mm in diameter and 2 mm thick. The surface of the composites facing the cameras was sprayed with a fine layer of black paint. The unsprayed surface of each sample, opposite the one facing the cameras, was light cured for 40 seconds using a light-emitting diode unit. Digital images were taken immediately before and after light curing. Shrinkage was calculated as von Mises strains, and z-axis displacements were measured in microns. The data were statistically analyzed using two-way ANOVA at a = .05. No significant difference in strain was observed between the two materials (P > .05). Strain distribution was nonhomogenous--the outer segments showed significantly higher strains than central parts in each material (P < .05). The opposite was observed for z-axis displacements-significantly greater displacements were found in central parts compared to the outer segments (P < .05). Different shrinkage vectors across the surface of the tested flowable composites showed predominant in-plane shrinkage of the outer surface segments and out-of-plane shrinkage of the inner segments. These complex local deformation patterns in composite materials indicate zones of different types of forces exerted on the tooth-restoration interface in situ.