title: Internal bleaching of teeth: an analysis of 255 teeth.
abstract: BACKGROUND
  Studies about bleaching have not analysed factors that affect the outcome. This aim of this study was to analyse the outcome of, and the factors associated with bleaching.
  
  
  METHODS
  Internal bleaching was done on 255 teeth in 203 patients. Colour was assessed pre-operatively, postoperatively and at recalls. The cause and type of discolouration, number of applications, bleaching outcome, and colour stability were assessed.
  
  
  RESULTS
  The most common teeth were upper central (69 per cent) and lateral (20.4 per cent) incisors. Trauma was the most common cause (58.8 per cent), followed by previous dental treatment (23.9 per cent), pulp necrosis (13.7 per cent) and pulp canal calcification (3.6 per cent). Dark yellow and black teeth required more applications of bleach than light yellow and grey teeth. Colour modification was "good" (87.1 per cent) or "acceptable" (12.9 per cent). Teeth restored with glass ionomer cement/composite resin had good colour stability, but this was less predictable with other restorations. No teeth had external invasive resorption.
  
  
  CONCLUSIONS
  Bleaching endodontically treated teeth was very predictable, especially for grey or light yellow discolourations. Glass ionomer cement/composite restorations were effective at preventing further discolouration. Patient age and tooth type did not affect treatment outcome and no cases of external invasive resorption were observed.
authors.affiliation: School of Dentistry, The University of Western Australia, Nedlands WA. paul.v.abbott@uwa.edu.au
authors.forename: P
authors.initials: P
authors.lastname: Abbott
authors.forename: S Y S
authors.initials: SY
authors.lastname: Heah
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D002648:Child; D003784:Dental Pulp Calcification / Q000150:complications; D003790:Dental Pulp Necrosis / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D023861:Photography, Dental; D012189:Retrospective Studies; D012390:Root Canal Therapy / Q000009:adverse effects; D018709:Statistics, Nonparametric; D014073:Tooth Bleaching / Q000379:methods*; D014075:Tooth Discoloration / Q000209:etiology / Q000628:therapy*; D018677:Tooth Injuries / Q000150:complications; D019553:Tooth, Nonvital / Q000628:therapy; D016896:Treatment Outcome; D055815:Young Adult