title: Effect of calcium hydroxide on ph changes of the external medium after intracoronal bleaching.
abstract: OBJECTIVE
  This in vitro study evaluated the effect of calcium hydroxide on pH changes of the external medium after intracoronal bleaching.
  
  
  METHODS
  A total of 50 extracted human premolars were prepared and filled with gutta-percha and endodontic sealer. The teeth were randomly divided into five groups according to the bleaching agents employed: (a) Sterile cotton pellet with distilled water (control group); (b) sodium perborate and distilled water; (c) sodium perborate and 10% carbamide peroxide; (d) sodium perborate and 35% hydrogen peroxide; (e) 35% hydrogen peroxide. The teeth were stored in vials containing distilled water and the pH values of the medium surrounding the teeth were analyzed. After 7-day storage, the bleaching agent was removed and replaced by calcium hydroxide, and the distilled water was changed, in which the teeth were kept stored for further 14 days. Measurement of pH of the external medium (distilled water) was performed 7 days after insertion of the bleaching agents, immediately, 7 and 14 days after insertion of the calcium hydroxide. Data were submitted to statistical analysis by the two-way ANOVA and Tukey,s test.
  
  
  RESULTS
  There were pH changes of the external medium at 7- day period after bleaching procedures. These results confirmed the diffusion of bleaching agents to the external medium.
  
  
  CONCLUSIONS
  Calcium hydroxide increased the external medium pH and was effective for pH alkalinization after intracoronal bleaching.
  
  
  CONCLUSIONS
  Intracoronal bleaching of endodontically treated teeth may cause cervical root resorption. A possible explanation for this process is the passage of bleaching agents to the periodontal tissues yielding an inflammatory process. In an attempt to keep the neutrality of the periodontal pH, the calcium hydroxide has been recommended.Results of this study showed that this material should be always used after intracoronal bleaching.
authors.affiliation: Department of Restorative Dentistry, São Josédos Campos School of Dentistry, UNESP São Paulo State University São Paulo, Brazil.
authors.forename: Patricia Marra de
authors.initials: PM
authors.lastname: Sa
authors.forename: Raffaela Di Iorio
authors.initials: RD
authors.lastname: Jeronymo
authors.forename: Karen Cristina Kazue
authors.initials: KC
authors.lastname: Yui
authors.forename: Eduardo Galera da
authors.initials: EG
authors.lastname: Silva
authors.forename: Maria Filomena Rocha Lima
authors.initials: MF
authors.lastname: Huhtala
authors.forename: Carlos Rocha Gomes
authors.initials: CR
authors.lastname: Torres
authors.forename: Ana Paula Martins
authors.initials: AP
authors.lastname: Gomes
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D002126:Calcium Hydroxide / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D012391:Root Resorption / Q000209:etiology / Q000517:prevention & control; D018709:Statistics, Nonparametric; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000009:adverse effects / Q000737:chemistry*; D019553:Tooth, Nonvital; D014867:Water / Q000737:chemistry*
chemical_list: D058205:Tooth Bleaching Agents; D014867:Water; D002126:Calcium Hydroxide