title: In-office bleaching with a two- and seven-day intervals between clinical sessions: A randomized clinical trial on tooth sensitivity.
abstract: OBJECTIVE
  In-office bleaching is usually performed in 2-3 sessions with one-week interval. The impact of shorter interval times on tooth sensitivity has not been evaluated. This study aimed to compare the absolute risk of tooth sensitivity (TS) and colour change after in-office bleaching with a two- and seven-day intervals between sessions.
  
  
  METHODS
  We selected for this randomized, single-blind study, 40 patients with colour C2 or darker. We performed two bleaching sessions with a 35% hydrogen peroxide gel with either a 1-week or 2-day interval. We recorded the TS up to 48 h with a VAS scale and the colour at baseline and 30 days after bleaching with a value-oriented shade guide and a spectrophotometer. The risk and intensity of TS were compared with the Fisher's exact test and two-way repeated measures ANOVA. Colour change (ΔSGU and ΔE) were evaluated by Student's t-test (alpha=5%).
  
  
  RESULTS
  Approximately 60% of the participants reported TS (65% and 55% for the 7 and 2-day groups). A significant whitening of approximately 6 shade guide units was detected for both groups. No difference was detected between groups.
  
  
  CONCLUSIONS
  The reduction of the interval between bleaching sessions from seven to two days reduced the treatment time without increasing the bleaching-induced TS (clinicaltrials.gov identifier: NCT1959789).
  
  
  CONCLUSIONS
  In-office bleaching with a 2-day interval did not increase the risk and intensity of bleaching-induced tooth sensitivity.
authors.affiliation: School of Dentistry, Paranaense University, Umuarama, Paraná, Brazil.
authors.forename: Eloisa Andrade
authors.initials: EA
authors.lastname: de Paula
authors.affiliation: School of Dentistry, Paranaense University, Umuarama, Paraná, Brazil.
authors.forename: Jéssica Andressa
authors.initials: JA
authors.lastname: Nava
authors.affiliation: School of Dentistry, Paranaense University, Umuarama, Paraná, Brazil.
authors.forename: Cheilla
authors.initials: C
authors.lastname: Rosso
authors.affiliation: School of Dentistry, Paranaense University, Umuarama, Paraná, Brazil.
authors.forename: Cristina Monteiro
authors.initials: CM
authors.lastname: Benazzi
authors.affiliation: School of Dentistry, Paranaense University, Umuarama, Paraná, Brazil.
authors.forename: Karen Tamura
authors.initials: KT
authors.lastname: Fernandes
authors.affiliation: School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Stella
authors.initials: S
authors.lastname: Kossatz
authors.affiliation: School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Alessandro Dourado
authors.initials: AD
authors.lastname: Loguercio
authors.affiliation: School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil. Electronic address: reis_ale@hotmail.com.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
mesh_terms: D003770:Dental Offices; D003807:Dentin Sensitivity / Q000139:chemically induced / Q000453:epidemiology*; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects*; D008297:Male; D016037:Single-Blind Method; D058205:Tooth Bleaching Agents / Q000009:adverse effects*; D014075:Tooth Discoloration / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D058205:Tooth Bleaching Agents; D006861:Hydrogen Peroxide
keywords: Dentine sensitivity; Randomized controlled trial; Tooth bleaching