Increased whitening efficacy and reduced cytotoxicity are achieved by the chemical activation of a highly concentrated hydrogen peroxide bleaching gel

Abstract

Objective: This study was designed for the chemical activation of a 35% hydrogen peroxide (H 2 O 2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. Methodology: First, the bleaching gel-associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT)-was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H 2 DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). Results: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. Conclusion: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.

Efficacy of natural, peroxide‐free tooth‐bleaching agents: A systematic review, meta‐analysis, and technological prospecting

“…At the same time, the elimination of these free radicals by the presence of enzymatic and non‐enzymatic antioxidants in the extract limits its deleterious effects on the enamel (Gopinath et al, ; Spychalla & Desborough, ). A recent study showed that the peroxidase may induce the formation of oxidative intermediates through the one‐electron reduction step, called peroxidase cycle (Soares et al, ). This would increase the oxidative potential of hydrogen peroxide, leading to an increase in free radical liberation, also increasing bleaching efficiency and reducing the deleterious effects in the pulp cells (Soares et al, ).…”

“…A recent study showed that the peroxidase may induce the formation of oxidative intermediates through the one‐electron reduction step, called peroxidase cycle (Soares et al, ). This would increase the oxidative potential of hydrogen peroxide, leading to an increase in free radical liberation, also increasing bleaching efficiency and reducing the deleterious effects in the pulp cells (Soares et al, ).…”

“…These molecules diffuse through enamel and dentin, producing oxidation of tooth pigments; this chemical reaction is what provides the bleaching effect (Hortkoff, Bittencourt, Nadal, & Rezende, ). The by‐products of this reaction can reach the pulp chamber (Shackelford, Kaufmann, & Paules, ; Young, Fairley, Mohan, & Jumeaux, ) and cause serious damage to pulp tissue, especially to odontoblasts underlying dentin (Li & Greenwall, ; Moghadam et al, ; Tredwin, Naik, Lewis, & Scully, ); this may affect the regenerative potential of pulp cells, once it induces pro‐inflammatory cytokine release (Attin, Vollmer, Wiegand, Attin, & Betke, ; Soares et al, ).…”

“…One recent study (Munchow et al, ) evaluates bromelain and papain as alternatives to the traditional bleaching agents; the authors suggest that these proteases can break down the protein from the spots attached to the surface of the enamel, reducing them into smaller parts, increasing the lightness of tooth and consequently causing a bleaching effect. Another study (Soares et al, ) has shown that enzymatic activation with peroxidase improves biocompatibility and aesthetic efficiency of peroxide‐based gels.…”

Polymeric biomaterials maintained the esthetic efficacy and reduced the cytotoxicity of in‐office dental bleaching

“…7,11 With the aim of preventing cellular damage resulting from professional bleaching, and consequently making these therapy safer, various researchers have proposed the addition of catalyst agents to the gels used in-office, based on understanding of the kinetic behavior of H 2 O 2 . [12][13][14] Ortecho-Zuta et al 13 demonstrated that the incorporation of 10 mg/ml of the enzyme Horseradish Peroxidase (HRP) into a bleaching gel with 35%H 2 O 2 limited the trans-amelodentinal cytotoxicity of the product and increased its bleaching efficacy right after the 1st session. The subproducts generated by the decomposition of H 2 O 2 , such as the hydroxyl radical (HO • ), peri-hydroxyl (HO 2…”