title: Evaluation of subsurface defects created during the finishing of composites.
abstract: The objective of this study was to test the hypothesis that a degraded subsurface layer containing microcracks is produced in dental composites as a result of finishing procedures. Various composites in the form of rectangular bars were finished with a 12-fluted carbide bur or a fine diamond within minutes of light-curing, and were subsequently stained with silver nitrate. Microscopic evaluation revealed that significant penetration of stain occurred in the unfinished as well as in the finished surfaces. The extent of dye penetration that could be directly attributed to a damaged layer produced by the finishing procedure was less than 10 microns, being greatest for a microfill (Silux Plus) and a hybrid (P-50) composite. There was no difference between the effects of the finishing instruments. SEM analysis of the subsurface showed an absence of any cracks for the composites. However, occasional disruption of the interface between the pre-polymerized resin fillers and the matrix was apparent for the microfill material. The results showed that only a very limited subsurface damage may be created in certain composites during the initial contouring of a restoration.
authors.affiliation: Department of Dental Materials Science, Oregon Health Sciences University, Portland 97201.
authors.forename: J L
authors.initials: JL
authors.lastname: Ferracane
authors.forename: J R
authors.initials: JR
authors.lastname: Condon
authors.forename: J C
authors.initials: JC
authors.lastname: Mitchem
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins / Q000737:chemistry*; D003775:Dental Polishing; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D019279:Resin Cements; D012835:Silver Nitrate; D013194:Staining and Labeling; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C065770:Herculite XR; C065771:P50 composite resin; C074741:Silux Plus; D017438:Bisphenol A-Glycidyl Methacrylate; D012835:Silver Nitrate