title: Shear bond strengths of buccal tubes.
abstract: OBJECTIVE
  To investigate the shear bond strengths of buccal tubes and to determine the sites of failure.
  
  
  METHODS
  Four orthodontic buccal tubes were selected: A, American Orthodontics; B, 3M Unitek - small base; C, 3M Unitek--large base; D, Hangzhou Dentop. Twenty buccal tubes from each group were bonded to the buccal surfaces of lower right first molars with the same light-cured composite resin. The buccal tubes were debonded with a universal testing machine and the data analysed. The amount of adhesive remaining on the teeth after debonding was classified with the modified adhesive remnant index (ARI).
  
  
  RESULTS
  The groups ranked from the highest to lowest bond strength (MPa) were: B, A, D and C. The bond strengths of the buccal tubes, except Groups A and B, were significantly different (p < 0.05). The majority of the buccal tubes (63 per cent) had modified ARI scores of 1 and 2 and 25 per cent of the tubes had scores of 4 and 5. After debonding, no adhesive remained on 40 per cent of the teeth in Groups B and D.
  
  
  CONCLUSIONS
  The shear bond strengths of the buccal tubes fell below the value considered to be clinically acceptable. There were no differences between the shear bond strengths of the buccal tubes with photoetched and microetched bases. The buccal tubes with the largest base failed prematurely, possibly because the unsupported bonding pad flexed during debonding.
authors.affiliation: Department of General Dental Practice and Oral and Maxillofacial Imaging, Dental Faculty, University Malaya, Kuala Lumpur, Malaysia. drkathi@myjaring.net
authors.forename: Kathiravan
authors.initials: K
authors.lastname: Purmal
authors.forename: Prema
authors.initials: P
authors.lastname: Sukumaran
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D003188:Composite Resins / Q000737:chemistry; D003743:Dental Enamel / Q000648:ultrastructure; D045662:Dental Etching / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008963:Molar; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C516047:Transbond XT Light Cure Adhesive Primer; D014867:Water