title: An optimized synthetic substrate for orthodontic bond strength testing.
abstract: OBJECTIVE
  The purpose of this study was to investigate the suitability of different synthetic calcium phosphate based substrates as a biomimetic enamel surface model for orthodontic bond strength testing.
  
  
  METHODS
  Carbonated apatite, amorphous calcium phosphate and commercial hydroxyapatite specimens were prepared as substrates for orthodontic bond strength testing. Carbonated apatite specimens were prepared by pressing, sintering and treatment with NaF. The shear bond strength was measured with a universal testing machine.
  
  
  RESULTS
  Hydroxyapatite, amorphous and cold pressed carbonated hydroxyapatite exhibited fractures within the substrate after debonding. Mean bond strength values for carbonated hydroxyapatite were 7.38 (1.75) MPa for specimens pressed at 300 degrees C and 9.55 (2.23) MPa for specimens pressed at 300 degrees C and then sintered at 600 degrees C. An additional NaF treatment after sintering resulted in lower bond strength measurements of on average 6.52 (1.03) MPa.
  
  
  CONCLUSIONS
  Hot pressed and sintered carbonated hydroxyapatite showed acceptable shear bond strength values and may represent a suitable biomimetic model for orthodontic bond strength testing.
mesh_terms: D001031:Apatites / Q000737:chemistry; D040761:Biomimetic Materials / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel; D003799:Dental Stress Analysis / Q000295:instrumentation; D017886:Durapatite / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D011312:Pressure; D012969:Sodium Fluoride / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature
chemical_list: D001031:Apatites; D002130:Calcium Phosphates; D002254:Carbonates; C519480:amorphous calcium phosphate; D012969:Sodium Fluoride; D017886:Durapatite