Histochemical analysis of dental hard tissues following bleaching.

Hydrogen peroxide in the form of carbamide peroxide is widely used for tooth whitening (bleaching), both in professionally- and in self-administered products. Adverse effects have become evident. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. Tooth sensitivity is experienced in 15-78% of patients undergoing external tooth bleaching. However, clinical studies addressing other adverse effects are lacking. Direct contact with hydrogen peroxide induces genotoxic effects in bacteria and cultured epithelial cells, but the effect is reduced or totally abolished in the presence of metabolising enzymes. Several carcinogenesis studies, including the hamster cheek pouch model, indicate that hydrogen peroxide (H(2)O(2)) might possibly act as a promoter. Until further clinical research is concluded to address the question of possible carcinogenicity, it is recommended that: tooth-bleaching products using concentrated H(2)O(2) should not be used without gingival protection; that H(2)O(2) containing products should be avoided in patients with damaged or diseased soft tissues. For nightguard vital bleaching, minimal amounts of low dose H(2)O(2) (including in the form of carbamide peroxide) are preferred, thereby avoiding prolonged and concentrated exposures.

/pdf/hydrogen-peroxide-tooth-whitening-bleaching-products-review-33bvtwyc23.pdf

Hydrogen peroxide tooth-whitening (bleaching) products: Review of adverse effects and safety issues

There has been recent concern about the inadvertent exposure of dentin with patent tubules as well as gingiva to bleaching systems containing 10-15% carbamide peroxide or 2-10% hydrogen peroxide for more than a few minutes. The aims of the present study were: (1) to determine the cytotoxicity of dilutions of hydrogen peroxide in cell culture; (2) to measure hydrogen peroxide diffusion from bleaching agents through dentin in vitro; and (3) to determine the risk of hydrogen peroxide-induced cytotoxicity from exposure of dentin to these vital bleaching agents. The 50% inhibitory dose (ID50) of hydrogen peroxide to succinyl dehydrogenase activity in cultured cells was found to be 0.58 mmol/L after 1 h. All bleaching materials demonstrated diffusion of hydrogen peroxide through dentin in an "in vitro pulp chamber" device. The one- and six-hour diffusates of all bleaching agents through 0.5-mm dentin exceeded the ID50 in monolayer cultures. Inhibition of succinyl dehydrogenase activity corresponded to the amount of hydrogen peroxide that can rapidly diffuse through dentin in vitro and reach concentrations which are toxic to cultured cells in less than 1 h.

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/66707/10.1177_00220345930720051501.pdf;sequence=2

Cytotoxicity and Dentin Permeability of Carbamide Peroxide and Hydrogen Peroxide Vital Bleaching Materials, in vitro

Tooth whitening products may be in contact with intraoral structures for several hours or they may be used daily to whiten the teeth. Consequently, these products should have a relatively neutral pH to minimize potential damage. This study measured the pH of 26 commercially available tooth-whitening products. The pH of the different whitening products ranged from 3.67 (highly acidic) to 11.13 (highly basic). The dentist-supervised home-bleaching products had a mean pH of 6.48 (range 5.66 to 7.35). The over-the-counter whitening products had a mean pH of 8.22 (range 5.09 to 11.13), and the whitening toothpastes had a mean pH of 6.83 (range 4.22 to 8.35). The 3 in-office bleaching products had a pH between 3.67 and 6.53. One-way ANOVA showed that there was a significant difference between the 4 product categories. The most basic pH of all the products tested was 11.13 for the whitening gel of Natural White-Rapid White. The most acidic pH of all products tested was 3.67 for Opalescence Xtra 35% hydrogen peroxide in-office bleach. The Least-Squares-Means test showed that the over-the-counter category had a pH significantly different from the other categories (p < 0.05).

/pdf/the-ph-of-tooth-whitening-products-33q63vt789.pdf

The pH of tooth-whitening products.

Extracted human premolars were cut, cleaned and divided into 6 experimental groups. Each group was treated with one of the following bleaching materials: 30% hydrogen peroxide, 10% carbamide peroxide, sodium perborate, Nu-Smile, Opalescence and DentlBright. Morphological changes in tooth surface occurred following treatment with most bleaching agents. Hydrogen peroxide and DentlBright were associated with surface changes in all dental tissues. Hydrogen peroxide, DentlBright, Nu-Smile and Opalescence were mainly associated with surface changes in the cementum, which exhibited more changes than the other tissues.

Surface morphology changes in human enamel, dentin and cementum following bleaching: a scanning electron microscopy study.

Hydrogen peroxide has been advocated for many years as an oral rinse useful in control of various oral conditions. Several authorities, however, have suggested that this material may be harmful to oral tissues, especially if the tissues have been previously injured. This article presents two case reports demonstrating harmful oral effects from hydrogen peroxide rinses. The findings suggest that oral hygiene techniques emphasizing the use of 3% hydrogen peroxide in periodontal therapy may require reevaluation.

Charles F. Orth

Papers

Oral ulcerations with use of hydrogen peroxide.