title: Three-dimensional evaluation of gap formation of cervical restorations.
abstract: OBJECTIVE
  In some studies gap formation has been evaluated in just one section of the restorative. This in vitro study aimed to design a quantitative three-dimensional method for evaluation of the contraction gap in restoratives.
  
  
  METHODS
  Cervical cavities were prepared on buccal, palatal or lingual surfaces in human extracted molars and were then filled with resin composites. Specimens were reduced every 100 microm in a direction parallel to the tooth axis, and perpendicular to the cavity floor from one proximal side to the other. The sequence of reducing the sections by 100 microm, image taking (250x) and observation of these images (maximal 2500x) were repeated. Three-dimensional images of the contraction gap were made using analytical software and the proportions of the interface with gap formation calculated.
  
  
  RESULTS
  The mean proportions of the interface with gap formation of the self-etching system (Clearfil Liner Bond II Sigma) was 41.7+/-6.3% and that of the self-priming system (Single Bond) was 38.2+/-3.9%; there was no significant difference.
  
  
  CONCLUSIONS
  Approximate three-dimensional images of the in vitro contraction gap could be drawn and the mean proportions of the interface with gap formation could be more precisely calculated than by previous methods.
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan. y-iwami@dent.osaka-u.ac.jp
authors.forename: Yukiteru
authors.initials: Y
authors.lastname: Iwami
authors.forename: Ayako
authors.initials: A
authors.lastname: Shimizu
authors.forename: Mikako
authors.initials: M
authors.lastname: Hayashi
authors.forename: Fumio
authors.initials: F
authors.lastname: Takeshige
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Ebisu
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000379:methods; D003739:Dental Cementum / Q000648:ultrastructure; D003743:Dental Enamel / Q000648:ultrastructure; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D013499:Surface Properties; D019237:Tooth Cervix / Q000648:ultrastructure*
chemical_list: C112274:Clearfil Liner Bond 2; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate