title: Influence of enamel border and regional variability on durability of resin-dentin bonds.
abstract: OBJECTIVE
  To evaluate the influence of enamel border on regional resin-dentin microtensile bond strength (muTBS) over time.
  
  
  METHODS
  Thirty human third molars had a flat dentine surface exposed. Two adhesive systems (Single Bond [SB] and ScotchBond Multi Purpose Plus [SBMP]) were applied and composite resin crowns (Filtek Z250) were constructed. Teeth were divided into three groups (n=5). Group A, specimens were sectioned to obtain sticks to be tested in tension (0.5mm/min) immediately. Group B specimens were stored without outer enamel in water for 6 months, before sectioning and testing. Group C, specimens were stored with outer enamel in water for 6 months, before sectioning and testing. In all groups, the origin of the sticks, periphery and inner regions was controlled. The data for each adhesive were subjected to a two-way repeated measure ANOVA (location versus storage conditions) and Tukey's test.
  
  
  RESULTS
  No significant degradation in muTBS was observed for SBMU in all conditions. For SB, a significant reduction on muTBS was observed in the specimens without enamel border (group B). The degradation was more pronounced in the specimens from the periphery.
  
  
  CONCLUSIONS
  The three-step etch-and-rinse system is less susceptible to water degradation effects; stable resin-dentin bonds can be achieved with two-step etch-and-rinse systems as long as there is a bonded enamel border.
authors.affiliation: Department of Dental Materials and Operative Dentistry, School of Dentistry, University of Oeste de Santa Catarina, Joaçaba, SC, Brazil.
authors.forename: Giovana Portella
authors.initials: GP
authors.lastname: Gamborgi
authors.forename: Alessandro D
authors.initials: AD
authors.lastname: Loguercio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D003737:Dental Cavity Preparation; D003743:Dental Enamel / Q000502:physiology*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008964:Molar, Third; D019279:Resin Cements; D013718:Tensile Strength; D014867:Water
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate