title: Thermocycling--the effects upon the compressive strength and abrasion resistance of three composite resins.
abstract: The purpose of this investigation was to examine the effects of thermocycling upon the compressive strength and abrasive wear resistance of three commercial composites Fulfil, P-50 and Herculite-XR. Specimens of each material were divided into five treatment groups comprising a control, and four different cycling and storage regimes. Tests for compressive strength and wear resistance were carried out. Prior to testing all specimens were stored in distilled water for 1 week. Three groups were stored at a temperature of 37 degrees C and the remaining two at 60 degrees C. Thereafter all groups that were thermocycled were subjected to 750 cycles of a thermocycling regime consisting of the cycle ACAB where A and B represent the fixed temperatures of 37 degrees C and 5 degrees C, and C, depending upon the treatment group, either 50 degrees C or 60 degrees C. One-way analyses of variance upon the compressive strength and wear factor data following the treatments highlighted significant differences in the mean compressive strength for all materials (Fulfil (P < 0.05), P-50 and Herculite-XR (P < 0.01)) and in the wear factor values for only Fulfil and P-50 (P < 0.001). Surprisingly, thermocycling P-50 with an upper temperature limit of 50 degrees C had catastrophic consequences upon the measured properties. It is concluded that some of the observed behaviour may have potentially detrimental consequences upon the long-term clinical durability of the materials tested.
authors.affiliation: Department of Conservative Dentistry, Dental School, University of Dundee, U.K.
authors.forename: R G
authors.initials: RG
authors.lastname: Chadwick
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis; D006358:Hot Temperature; D016018:Least-Squares Analysis; D016014:Linear Models; D008422:Materials Testing; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements; D018709:Statistics, Nonparametric; D013499:Surface Properties; D016019:Survival Analysis
chemical_list: D003188:Composite Resins; D011140:Polyurethanes; D019279:Resin Cements; C065770:Herculite XR; C065771:P50 composite resin; D017438:Bisphenol A-Glycidyl Methacrylate; C046503:formula F 70