title: Evaluation of bovine and human teeth exposed to thermocycling for microleakage under bonded metal brackets.
abstract: BACKGROUND
  Bovine teeth are commonly used as substitutes for human teeth in scientific investigations. The present study was performed in vitro with the objective of comparing bovine and human enamel subjected to thermocycling for microleakage beneath metal brackets.
  
  
  METHODS
  A total of 50 bovine and human teeth (25 per group) void of defects or carious decay were extracted and stored in chloramine B (0.5%). A light-curing adhesive (Transbond™ XT) was used as instructed by the manufacturer (3M Unitek, Monrovia, CA, USA) to bond a metal bracket (discovery®; Dentaurum, Ispringen, Germany) to the surface of each tooth following 30 s of enamel etching (phosphoric acid 35%). After 24 h of dye penetration in methylene blue (0.5%), the cervical and incisal bracket surfaces were analyzed by light microscopy for excess bonding material, dye penetration, and microleakage at the bracket-adhesive and adhesive-enamel interfaces. Staining and evaluation was repeated after thermocycling (5000 cycles at 5/55 °C).
  
  
  RESULTS
  Before thermocycling, the number of human teeth showing marginal gaps was one-third the number of bovine teeth (p<0.001). After thermocycling, the distribution of gaps was similar (p=0.180). The adhesive-enamel interface was most frequently affected (on 74% of human and 64% of bovine teeth). No dye penetration in either group after examining a horizontal slice through the bracket basis was observed.
  
  
  CONCLUSIONS
  Immediately after bonding, less microleakage was observed around the base of metal brackets on human than bovine teeth. These marginal gaps were, however, superficial in both groups, none of them involving deep penetration of dye under the bracket base.
authors: Policlinic of Orthodontics, Johannes Gutenberg University, Mainz, Germany. canbek@uni-mainz.de
authors: Kerem
authors: K
authors: Canbek
authors: Mareike
authors: M
authors: Karbach
authors: Franziska
authors: F
authors: Gottschalk
authors: Christina
authors: C
authors: Erbe
authors: Heinrich
authors: H
authors: Wehrbein
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D002417:Cattle; D003080:Cold Temperature; D001840:Dental Bonding / Q000009:adverse effects* / Q000379:methods*; D003763:Dental Leakage / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D019544:Equipment Failure Analysis; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D023421:Models, Animal; D016910:Orthodontic Brackets / Q000009:adverse effects*; D013045:Species Specificity; D014070:Tooth / Q000503:physiopathology*; D016896:Treatment Outcome