title: Enamel colour changes after debonding using various bonding systems.
abstract: OBJECTIVE
  To test the possible association between enamel colour alteration and resin tag depth.
  
  
  METHODS
  In vitro laboratory study.
  
  
  METHODS
  Department of Orthodontics, Alexandria University, Egypt.
  
  
  METHODS
  Fifty freshly extracted human premolar teeth were equally divided randomly into a control and four experimental groups. Teeth in group I received only enamel prophylaxis. Teeth in groups II and III were etched with 35% phosphoric acid for 15 and 60 seconds, respectively. Teeth in group IV were conditioned with Prompt L-pop self-etching primer and in group V with Xeno III self-etching primer, according to the manufacturer's instructions. Orthodontic brackets were bonded to the teeth in all experimental groups using Transbond XT composite. Following bracket debonding, finishing and polishing were performed. Enamel colour was evaluated spectrophotometrically at baseline and then after debonding, with the corresponding colour differences ΔE calculated. Resin tags lengths were measured on sectioned teeth in each experimental group under scanning electron microscope.
  
  
  RESULTS
  All experimental groups showed clinically perceivable colour change after debonding and finishing as all values were exceeded the clinical colour detection threshold of ΔE = 3.7 units. Significant differences (P<0.05) in resin tag length were found in all experimental groups. Significant moderate correlation was found between colour change and resin tags length when all teeth were combined and tested, irrespective of group.
  
  
  CONCLUSIONS
  Moderate evidence exists that shorter resin tag penetration produces less change in enamel colour following clean-up and polishing. Self-etch primers produce less resin penetration and these systems may produce less iatrogenic colour change in enamel following orthodontic treatment.
authors: Alexandria University, Alexandria, Egypt. azaher@idsc.net.eg
authors: Abbas R
authors: AR
authors: Zaher
authors: Essam M
authors: EM
authors: Abdalla
authors: Maha A
authors: MA
authors: Abdel Motie
authors: Noman Atiq
authors: NA
authors: Rehman
authors: Hassan
authors: H
authors: Kassem
authors: Athanasios E
authors: AE
authors: Athanasiou
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000293:Adolescent; D002648:Child; D003116:Color; D001840:Dental Bonding / Q000379:methods*; D017005:Dental Debonding / Q000379:methods*; D003743:Dental Enamel / Q000033:anatomy & histology* / Q000648:ultrastructure; D003777:Dental Prophylaxis / Q000379:methods; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013053:Spectrophotometry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D017220:Dentin-Bonding Agents; D010756:Phosphoric Acids; C408584:Prompt L-Pop; D019279:Resin Cements; C477790:Transbond XT; C487957:Xeno III; C030242:phosphoric acid