title: Do bonding agents protect the bracket-periphery?--Evaluation by consecutive μCT scans and fluorescence measurements.
abstract: OBJECTIVE
  The aim of this in vitro study was to consecutively determine the effect of three bonding agents on the prevention of enamel demineralisation at the bracket-periphery and to compare the suitability of micro-computed tomography (μCT) scans and quantitative light-induced fluorescence (QLF) to detect changes within subsurface lesions.
  
  
  METHODS
  The effect of a resin-modified glass ionomer cement (RMGI) (Fuji Ortho LC), a compomer (Assure) and a composite (Transbond XT) on the prevention of enamel demineralisation at the bracket-periphery was examined. After 7, 14, 21 and 28 days of pH cycling, the teeth (N = 45) were examined by consecutive μCT scans and by using a customised QLF set-up.
  
  
  RESULTS
  Particularly for the RMGI and for the compomer, the QLF and μCT scans showed that the formation and the body of the lesion were not precisely located at the enamel next to the bracket margin. There was an area that was almost protected. The progression of demineralisation was decreased for the RMGI and the compomer-treated teeth.
  
  
  CONCLUSIONS
  For bonding orthodontic brackets, the RMGI and compomer were comparably able to decrease the progression of white spot lesions (WSL), although the RMGI showed marginally superior protection. Both methods (QLF and μCT scans) were suitable for investigating the longitudinal fluoride effects on WSL, though these effects were more accurately described by mineral (fluorescence) loss or volume changes than by lesion depth.
  
  
  CONCLUSIONS
  The progression of WSL at the bracket-periphery could be altered by using fluoride-releasing bonding agents for bracket application. This approach represents a minimally invasive preventive measure.
authors.affiliation: Department of Orthodontics, LMU-University, Munich, Germany, epaschos@med.uni-muenchen.de.
authors.forename: Ekaterini
authors.initials: E
authors.lastname: Paschos
authors.forename: Teresa
authors.initials: T
authors.lastname: Galosi
authors.forename: Karin C
authors.initials: KC
authors.lastname: Huth
authors.forename: Ingrid
authors.initials: I
authors.lastname: Rudzki
authors.forename: Andrea
authors.initials: A
authors.lastname: Wichelhaus
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Kunzelmann
mesh_terms: D000180:Acrylic Resins / Q000494:pharmacology*; D000538:Aluminum Silicates / Q000494:pharmacology*; D020770:Compomers / Q000494:pharmacology*; D005453:Fluorescence; D005899:Glass Ionomer Cements / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000494:pharmacology*; D017001:Tooth Demineralization / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D055114:X-Ray Microtomography
chemical_list: D000180:Acrylic Resins; D000538:Aluminum Silicates; C438705:Assure cement; D020770:Compomers; C095451:Fuji Ortho LC; D005899:Glass Ionomer Cements; D019279:Resin Cements; C477790:Transbond XT