title: Tooth discolouration and internal bleaching after the use of triple antibiotic paste.
abstract: OBJECTIVE
  To assess the discolouration of teeth with closed and open apices after placement of triple antibiotic paste (TAP, ciprofloxacin, metronidazole and minocycline) in the pulp chamber and whether discolouration could be reversed by internal bleaching procedures.
  
  
  METHODS
  Twenty extracted human mandibular premolars were divided into 2 groups (n = 10): teeth with closed apices (CA) and teeth with open apices (OA). After conventional access, the TAP was sealed in the pulp chamber for 3 weeks. The paste was removed by a rinse with sodium hypochlorite (NaOCl) and a mixture of sodium perborate and distilled water was sealed in the pulp chamber for 1, 2 and 3 weeks. The shade was measured by a spectrophotometer at six time periods: baseline (T0), after 3 weeks of placement of TAP (T1), after removal of TAP with a NaOCl rinse (T2) and after 1 (T3), 2 (T4) and 3 (T5) weeks of internal bleaching with sodium perborate paste. Data were collected based on the CIELAB-CIE1976 (L*a*b*) system and analysed using t-tests and anova.
  
  
  RESULTS
  A significant decrease in the mean values of L* (lightness) was observed after treatment with TAP (T1, P < 0.05). Considerable increases in these values after bleaching with sodium perborate (T3 < T4 < T5) were found in both groups. The only significant difference in the intergroup analysis was between T1 and T2, in which ΔE values in the OA group were higher (P = 0.04).
  
  
  CONCLUSIONS
  TAP discoloured the tooth structure, but discolouration could be reversed with sodium perborate paste. In general, teeth with closed and open apices had the same rates of discolouration and bleaching.
authors.affiliation: Division of Endodontics, Pontificia Universidade Catolica do Parana, Curitiba, Brazil.
authors.forename: A L
authors.initials: AL
authors.lastname: Kirchhoff
authors.affiliation: Department of Dentistry, University of Taubate, Taubate, Brazil.
authors.forename: D P
authors.initials: DP
authors.lastname: Raldi
authors.affiliation: Division of Pediatric Dentistry, College of Dentistry, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: A C
authors.initials: AC
authors.lastname: Salles
authors.affiliation: Division of Endodontics, College of Dentistry, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: R S
authors.initials: RS
authors.lastname: Cunha
authors.affiliation: Division of Endodontics, Faculty of Dentistry, Dalhousie University, Halifax, NS, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Mello
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D001641:Bicuspid; D001881:Borates / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000009:adverse effects*; D004338:Drug Combinations; D006801:Humans; D066298:In Vitro Techniques; D008795:Metronidazole / Q000009:adverse effects*; D008911:Minocycline / Q000009:adverse effects*; D014073:Tooth Bleaching / Q000379:methods*; D014075:Tooth Discoloration / Q000139:chemically induced* / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D001881:Borates; D004338:Drug Combinations; D008795:Metronidazole; D002939:Ciprofloxacin; D008911:Minocycline; C027707:sodium perborate
keywords: antibiotics; bleaching; discolouration; sodium perborate