A clinical assessment of the effects of 10% carbamide peroxide gel on human pulp tissue

Bleaching vital teeth with 10% carbamide peroxide gel is a routine procedur e in which there has been no evidence of associated permanent pulpal damage . Synthesis of the enzyme heme oxygenase-1 (HO-1) is increased after exposu re of eukaryotic cells to conditions of oxidative stress (including H2O2) a s a defense against the damaging effects of free radicals, Dental pulps wer e evaluated for HO-1 (aka Heat Shock Protein 32) presence in teeth treated with 10% carbamide peroxide. Seventeen intact first premolars scheduled for orthodontic extraction were bleached for 4 h immediately preceding extract ion. Fourteen additional premolars from the same individuals were not bleac hed. All 31 teeth were extracted, fixed, demineralized, frozen, sectioned, and immunostained with anti-HO-1 antibody using a standard ABC protocol. Th ere was no significant difference in the presence of HO-1 between total ble ached versus total unbleached teeth using the Fisher's Exact Test (p less t han or equal to 0.05). However, the histological findings could be interpre ted to suggest that coronal odontoblasts and endothelial cells in the under lying pulp proper may have the potential to respond to oxidative stress by increasing the synthesis; of HO-1 (HSP32). This could represent a component of an initial defensive response by specific cells in strategic locations in the pulp that precedes classical inflammatory pathways.