title: Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling.
abstract: OBJECTIVE
  This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations.
  
  
  METHODS
  Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5°C±2°C followed by 55°C±2°C - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (α=0.05).
  
  
  RESULTS
  The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition.
  
  
  CONCLUSIONS
  The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations.
authors.affiliation: Department of Dentistry, Federal University of Ceara, Sobral, CE, Brazil.
authors.forename: Denise Sá Maia
authors.initials: DS
authors.lastname: Casselli
authors.forename: André Luis
authors.initials: AL
authors.lastname: Faria-e-Silva
authors.forename: Henrique
authors.initials: H
authors.lastname: Casselli
authors.forename: Luis Roberto Marcondes
authors.initials: LR
authors.lastname: Martins
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003737:Dental Cavity Preparation; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects*; D018772:Dental Marginal Adaptation; D003804:Dentin / Q000737:chemistry / Q000187:drug effects*; D057133:Dentin Desensitizing Agents / Q000737:chemistry*; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D013997:Time Factors
chemical_list: C438313:Clearfil SE Bond; D003188:Composite Resins; D057133:Dentin Desensitizing Agents; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate
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