title: Effect of different storage conditions on the physical properties of bleached enamel: An in vitro vs. in situ study.
abstract: OBJECTIVE
  Evaluate the effect of different storage conditions on bleached enamel using Knoop microhardness (KHN) and colour variation.
  
  
  METHODS
  Forty-eight tooth blocks were divided into four groups (n=12), based on storage media (SM): purified water (PW), artificial saliva (AS), natural saliva (NS), in situ (IS). Three whitening sessions were carried out using 35% hydrogen peroxide, with a week interval. Colour and KHN measurements were taken before the samples were placed in the SM (t1), after 24h in the SM (t2), and after 24h at the end of the bleaching treatment (t3). Two extra samples from each group were analysed using a scanning electron microscope (SEM). KHN results were analysed by PROC-MIXED and Tukey-Kramer test (α=0.05), and colour changes were evaluated using ΔL, Δa, Δb, ΔE between the different times Δ1(t1-t2), Δ2(t2-t3) using the Kruskal-Wallis test and Dunn's test (α=0.05).
  
  
  RESULTS
  Significant statistical difference was noted in KHN at t3, with the lowest values found for PW. As for colour analysis in ΔE2 and Δb2, IS showed values that were statistically lower when compared to AS. Likewise, there were differences between PW and AS in relation to IS when evaluating ΔL2. In addition, NS showed similar values to IS.
  
  
  CONCLUSIONS
  The storage conditions had different effects on the physical properties of bleached enamel. NS was the only SM that showed similar behaviour to IS.
  
  
  CONCLUSIONS
  NS proved an effective SM in the protection and recovery of damage caused by bleaching and is a viable SM for in vitro studies.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil. Electronic address: mariliaz21@gmail.com.
authors.forename: Marília
authors.initials: M
authors.lastname: Zeczkowski
authors.affiliation: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil. Electronic address: litenuta@fop.unicamp.br.
authors.forename: Livia Maria Andaló
authors.initials: LMA
authors.lastname: Tenuta
authors.affiliation: Department of Social Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil. Electronic address: glaucia@fop.unicamp.br.
authors.forename: Gláucia Maria Bovi
authors.initials: GMB
authors.lastname: Ambrosano
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil. Electronic address: aguiar@fop.unicamp.br.
authors.forename: Flávio Henrique Baggio
authors.initials: FHB
authors.lastname: Aguiar
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil. Electronic address: deboralima@fop.unicamp.br.
authors.forename: Débora Alves Nunes Leite
authors.initials: DANL
authors.lastname: Lima
mesh_terms: D000328:Adult; D000818:Animals; D002417:Cattle; D003116:Color; D003743:Dental Enamel / Q000737:chemistry* / Q000187:drug effects* / Q000648:ultrastructure; D005260:Female; D006244:Hardness; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D066298:In Vitro Techniques; D008297:Male; D009195:Peroxidase / Q000737:chemistry; D011309:Preservation, Biological; D012463:Saliva / Q000737:chemistry; D012464:Saliva, Artificial / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D055815:Young Adult
chemical_list: D012464:Saliva, Artificial; D058205:Tooth Bleaching Agents; D014867:Water; D006861:Hydrogen Peroxide; D009195:Peroxidase
keywords: Artificial saliva; Colour; Hardness; Saliva; Storage; Tooth bleaching