title: Evaluating a method of artificially hypermineralizing dentin to simulate natural conditions in bonding studies.
abstract: OBJECTIVE
  This study tested an in vitro model of dentin hypermineralization, aiming to simulate naturally hypermineralized dentin for bond strength studies. The effect on bond strength of a double-etching treatment on the artificially hypermineralized substrate was also evaluated.
  
  
  METHODS
  Extracted human third molars were selected and 2 groups were formed: a group of 3 teeth, called N (normal dentin) and a group of 6 teeth, called H (hypermineralized dentin). Occlusal surfaces were ground flat to expose midcoronal dentin. Group H was subjected to artificial hypermineralization and subdivided into 2 subgroups: Ht and Hd. The exposed dentinal surfaces of group N and subgroup Ht were etched with 37% phosphoric acid for 15 s prior to bonding with Single Bond adhesive. Dentin of the subgroup Hd was etched twice (double etching) prior to bonding with Single Bond. A 4-mm-high Z100 composite buildup was created on each tooth and, after 24 h water storage, bond strengths were evaluated by the microtensile method. The data between group N and subgroup Ht and between subgroups Ht and Hd were compared using the Student's t test (alpha = 0.05).
  
  
  RESULTS
  No significant difference was observed between bond strengths of group N and subgroup Ht (p = 0.108). Subgroup Hd was statistically different from Ht (p < 0.0001).
  
  
  CONCLUSIONS
  Bond strengths of Single Bond to artificially hypermineralized dentin did not differ statistically from those to normal dentin substrate. The double etching approach significantly reduced bond strengths of artificially hypermineralized dentin.
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Brazil. renatocilli@yahoo.com
authors.forename: Renato
authors.initials: R
authors.lastname: Cilli
authors.forename: Anuradha
authors.initials: A
authors.lastname: Prakki
authors.forename: Paulo Amarante
authors.initials: PA
authors.lastname: de Araújo
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002130:Calcium Phosphates / Q000494:pharmacology*; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003809:Dentin, Secondary / Q000139:chemically induced / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry
chemical_list: D002130:Calcium Phosphates; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D010756:Phosphoric Acids; C083568:Z100 composite resin; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium