In vivo analysis of the presence of heme oxygenase‐1, transcription factor Jun‐D, and CD90+/CD73+/CD105+/CD45‐ cells in the pulp of bleached teeth

AIM: To investigate hydrogen peroxide (H2 O2 )-induced responsiveness in pulp cells using heme oxygenase-1 (HO-1) immunolabelling, Jun-D immunolabelling to study the effects of H2 O2 on odontoblastic differentiation and CD90+/CD73+/CD105+/CD45- cell counting for in vivo identification of mesenchymal stem cells in the pulp. METHODOLOGY: The maxillary molars of 50 rats were treated with a bleaching gel (35% H2 O2 , 1 x 30 min) or placebo gel (control groups). At 2, 3, 7, 15 and 30 days after the treatment (n = 10), inflammation in pulp tissue was analysed by haematoxylin-eosin staining, HO-1- and Jun-D-immunolabelled cells were counted in each third of the pulp chamber, and the number of CD90+/CD73+/CD105+/CD45- cells was quantified by immunofluorescence. The results were assessed using the Paired t-test or Wilcoxon signed-rank test (P 0.05). CONCLUSIONS: Pulp cells responded to oxidative stress by expressing HO-1 during the post-bleaching inflammation phase until the beginning of the repair phase. Jun-D expression occurred during the reduction of inflammation and the beginning of tertiary dentine production. The presence of oxidative stress did not influence the number of CD90+/CD73+/CD105+/CD45- cells identified in vivo in the dental pulp.