title: Enamel demineralization and bracket bond strength when etching with acid and /or Er:YAG laser.
abstract: BACKGROUND
  Enamel etching for brackets is usually done with phosphoric acid. Er:YAG lasers have been recently used for this purpose with conflicting results. The effects of lasers on tooth demineralization and the effects of different combinations of laser treatments and bonding agents were evaluated in this study.
  
  
  METHODS
  The enamel contents of fluorine, calcium oxide and phosphorus pentoxide (P(2) O(5)) were analysed using acid etching, laser treatment or both. The tensile bond strength of metallic and ceramic brackets using Transbond XT and Fuji Ortho LC were also tested, using acid etching, laser treatment or a combination of both.
  
  
  RESULTS
  All treatments reduced the contents of fluorine, P(2)O(5) and calcium oxide, and acid reduced P(2) O(5) levels more than laser. The bond strength with laser was weaker than with acid, and stronger when combining both. When using laser, the best adhesive was the Fuji Ortho LC. The combination of laser and acid produced the best results when using Transbond XT.
  
  
  CONCLUSIONS
  The demineralization promoted by laser was lower than the one produced with acid. Laser treatment produced lower tensile stress strength than acid, but still enough to produce clinically efficient retention. The combination of laser and acid produced the best retention results.
authors.affiliation: Division of Sports Dentistry of Brazilian Dental Association, Minas Gerais, Brazil.
authors.forename: M F
authors.initials: MF
authors.lastname: Lasmar
authors.forename: V G S
authors.initials: VG
authors.lastname: Reher
authors.forename: R
authors.initials: R
authors.lastname: Lalloo
authors.forename: P
authors.initials: P
authors.lastname: Reher
mesh_terms: D000180:Acrylic Resins; D000538:Aluminum Silicates; D000704:Analysis of Variance; D017610:Calcium Compounds / Q000032:analysis; D001840:Dental Bonding; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects; D045662:Dental Etching / Q000379:methods*; D003799:Dental Stress Analysis; D005461:Fluorine / Q000032:analysis; D006801:Humans; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D010087:Oxides / Q000032:analysis; D010756:Phosphoric Acids; D017553:Phosphorus Compounds / Q000032:analysis; D019279:Resin Cements; D013052:Spectrometry, X-Ray Emission; D018709:Statistics, Nonparametric; D013718:Tensile Strength
chemical_list: D000180:Acrylic Resins; D000538:Aluminum Silicates; D017610:Calcium Compounds; C095451:Fuji Ortho LC; D010087:Oxides; D010756:Phosphoric Acids; D017553:Phosphorus Compounds; D019279:Resin Cements; C477790:Transbond XT; D005461:Fluorine; C012500:phosphorus pentoxide; C016538:lime; C030242:phosphoric acid