Penetration Capacity, Color Alteration and Biological Response of Two In-office Bleaching Protocols

Abstract

Hydrogen peroxide (H2O2) penetrates into the dental hard tissues causing color alteration but also alterations in pulpal tissues. Hard-tissue penetration, color alteration and the pulp response alterations were evaluated for two in-office bleaching protocols with H2O2. For trans-enamel/dentin penetration and color alteration, discs of bovine teeth were attached to an artificial pulp chamber and bleached according to the groups: BLU (20% H2O2 - 1x50 min, Whiteness HP Blue); MAX (35% H2O2 - 3x15 min, Whiteness HP Maxx); Control (1x50 min, placebo). Trans-enamel/dentin penetration was quantified based on the reaction of H2O2 with leucocrystal violet and the color analyzed by CIELab System. Twenty Wistar rats were divided into two groups (BLU and MAX) and their maxillary right molars were treated according to the same protocols of the in vitro study; the maxillary left molars were used as controls. After 2 days, the animals were killed and their maxillae were examined by light microscopy. The inflammation of pulp tissue was scored according to the inflammatory infiltrate (1, absent; 2, mild; 3, moderate; 4, severe/necrosis). Data were analyzed by statistical tests (α=0.05). MAX showed higher trans-enamel/dentinal penetration of H2O2 (p<0.05). The color alteration was similar for both groups (p>0.05), and different when compared to Control group (p<0.05). MAX showed severe inflammation in the upper thirds of the coronal pulp, and BLU showed moderate inflammation (p<0.05). In-office bleaching protocols using lower concentrations of hydrogen peroxide should be preferred due to their reduced trans-enamel/dentinal penetration since they cause less pulp damage and provide same bleaching efficiency.

Concentration‐dependent effect of bleaching agents on the immunolabelling of interleukin‐6, interleukin‐17 and CD5‐positive cells in the dental pulp

“…Studies have reported diffusion of H 2 O 2 into enamel and dentine (Cintra et al . ), reaching the dentine–pulp complex and reacting with pulp cells (Costa et al . , Cintra et al .…”

The effect of dental bleaching on pulpal tissue response in a diabetic animal model

“…, Cintra et al . ,b) and pulp necrosis (Cintra et al . ) caused by H 2 O 2 gels during dental bleaching procedures.…”

Effect of low‐level laser therapy combined with 5000 parts per million fluoride dentifrice on postbleaching sensitivity: A clinical, randomized, and double‐blind study

“…The low molecular weight of hydrogen peroxide (HP) promotes not only tooth bleaching but also the release of inflammatory mediators into the pulp, which may damage pulp cells and cause reversible pulpitis . A previous study of rat molars has shown that H 2 O 2 causes necrosis in the occlusal third of coronary pulp after one bleaching session . A similar outcome was found in a study of human teeth .…”