title: Lingual retainers bonded without liquid resin: a 5-year follow-up study.
abstract: BACKGROUND
  The aim of this in-vivo study study was to evaluate the effect of excluding the liquid resin component of a composite bonding product that is based on bisphenol A diglycidylmethacrylate when bonding lingual retainers.
  
  
  METHODS
  The material comprised 40 metal multistrand lingual retainers bonded onto the lingual surfaces of maxillary and mandibular anterior teeth. Transbond LR composite paste and liquid resin (3M Unitek, Monrovia, Calif) were used to bond retainers in the control group (20 retainers). The same bonding material was used in the test group (20 retainers), but the liquid resin component was excluded. The durations (in months) of retainer survival were analyzed by using the Kaplan-Meier product limit method and the log rank test.
  
  
  RESULTS
  Fifty percent of the retainers in the control group and 60% of those in the test group had no bond failures during the 5-year observation period; the difference was not statistically significant. Bond failures were recorded in 13.6% of the bonded tooth surfaces in the control group and in 14.9% in the test group; the difference was not statistically significant. On average, the retainers stayed intact in the control and test groups for 36 and 32 months, respectively. The median survival times of the control and test groups were 43 months and more than 47 months, respectively. Neither the survival analysis nor the 95% confidence intervals (24-49 months in the control group, 24-40 months in the test group) suggested any statistically significant difference between the groups.
  
  
  CONCLUSIONS
  Metal lingual retainers can be successfully bonded without liquid resin and serve the patient equally as well clinically as retainers bonded with the conventional bonding technique.
authors.affiliation: Assistant professor, Department of Orthodontics, University of Hong Kong, Hong Kong, China. athtang@hotmail.com
authors.forename: Alexander T H
authors.initials: AT
authors.lastname: Tang
authors.forename: Carl-Magnus
authors.initials: CM
authors.lastname: Forsberg
authors.forename: Anna
authors.initials: A
authors.lastname: Andlin-Sobocki
authors.forename: Jan
authors.initials: J
authors.lastname: Ekstrand
authors.forename: Urban
authors.initials: U
authors.lastname: Hägg
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D016022:Case-Control Studies; D001840:Dental Bonding / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D018704:Orthodontic Retainers; D016016:Proportional Hazards Models; D019279:Resin Cements / Q000737:chemistry*; D014072:Tooth Abrasion / Q000517:prevention & control*
chemical_list: D019279:Resin Cements; C481385:Transbond LR; D017438:Bisphenol A-Glycidyl Methacrylate