title: Fracture resistance of re-attached coronal fragments--influence of different adhesive materials and bevel preparation.
abstract: The purpose of this study was to investigate the fracture resistance of re-attached coronal fragments of teeth using different materials and tooth preparations. Seventy-two recently extracted bovine incisors were selected. Eight incisors were maintained without any preparation as a control group. The incisal third of the other teeth was sectioned using a diamond saw. In one group (n = 32), a 2-mm bevel was prepared, whereas in the second group no preparation was made (n = 32). The specimens (beveled and non-beveled) were divided in four groups (n = 8) and re-attached with the following materials: a dual-cured resin cement RelyX ARC (RX); a chemically cured composite Bisfil 2B (B2); a light-cured composite Z250 (Z2); and a one-bottle adhesive Single Bond (SB). The bevel region was restored with adhesive and composite. All materials were used according to manufacturer's directions. A light-curing unit was used to polymerize the materials. Specimens were stored in saline solution for 72 h. De-bonding procedures were performed in a testing machine with cross-head speed of 0.6 mm min(-1). The load was applied in the incisal third. The resistance to fracture for control group was 70 (7) kg. The fracture resistance for non-beveled and beveled specimens were: SB, 3.3 (2.4) and 17.0 (4.1); RX, 11.5 (3.0) and 16.3 (3.1); Z2, 14.4 (4.2) and 20.5 (1.7); and B2, 19.5 (3.5) and 32.5 (7.4) kg. Analysis of variance (anova) and Fisher's protected least significant difference (PLSD) test disclosed significant influence for materials and cavity designs (P = 0.001). The highest failure loads were obtained with the B2 group and then with the Z2 with either bevel or non-bevel. RX produced lower failure loads than the restorative composites. The lowest failure load was obtained with SB in the non-beveled group. No technique studied was able to attain the fracture resistance of the control group and both materials and tooth preparation influenced the fracture resistance.
authors.affiliation: Department of Operative Dentistry, Federal University of Pelotas, RS, Brazil. sancha@uol.com.br
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
authors.forename: Rose-Marie
authors.initials: RM
authors.lastname: Fay
authors.forename: Lilliam Marie
authors.initials: LM
authors.lastname: Pinzon
authors.forename: John M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D007180:Incisor / Q000293:injuries; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D019228:Tooth Crown / Q000293:injuries*; D014082:Tooth Fractures / Q000517:prevention & control* / Q000628:therapy
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; C115612:single bond; C078905:Bisfil; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate