title: Bisphenol A release from an orthodontic adhesive and its correlation with the degree of conversion on varying light-curing tip distances.
abstract: BACKGROUND
  The aims of this research were to use high-performance liquid chromatography to assess the bisphenol A (BPA) released from an orthodontic adhesive (Transbond XT; 3M Unitek, Monrovia, Calif) with various light-curing tip distances and to correlate the release to the degree of conversion.
  
  
  METHODS
  One hundred thirty-eight premolar brackets were divided into 3 groups of 40 each for the high-performance liquid chromatography analysis and 3 groups of 6 each for assessing the degree of conversion. Fourier transform infrared spectroscopy was used for this purpose. Each group was studied at light-curing tip distances of 0, 5, and 10 mm. Statistical analyses were performed by using 2-way analysis of variance (ANOVA), post-hoc multiple comparisons Tukey HSD tests, and paired t tests. Pearson correlation was used to assess the correlation between the degree of conversion and BPA release.
  
  
  RESULTS
  BPA release was greater in specimens cured with a greater light-curing tip distance. The degree of conversion decreased with increased light-curing tip distances. A negative correlation was found between BPA release and degree of conversion.
  
  
  CONCLUSIONS
  Clinicians should ensure that the adhesive is completely cured by keeping the light-curing tip as close to the adhesive as clinically possible.
authors.affiliation: Department of Orthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Chennai, India.
authors.forename: Catherine
authors.initials: C
authors.lastname: Sunitha
authors.forename: Vignesh
authors.initials: V
authors.lastname: Kailasam
authors.forename: Sridevi
authors.initials: S
authors.lastname: Padmanabhan
authors.forename: Arun B
authors.initials: AB
authors.lastname: Chitharanjan
mesh_terms: D000704:Analysis of Variance; D001559:Benzhydryl Compounds; D002851:Chromatography, High Pressure Liquid; D006244:Hardness; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D016910:Orthodontic Brackets; D010636:Phenols / Q000032:analysis*; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D017550:Spectroscopy, Fourier Transform Infrared; D018709:Statistics, Nonparametric; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D010636:Phenols; D019279:Resin Cements; C477790:Transbond XT; C006780:bisphenol A; D000098826:Bisphenol A Compounds