Nightguard vital bleaching: how safe is it?

The conservative technique for bleaching vital teeth using a nightguard and a 10% carbamide peroxide solution has captured the esthetic interests of the dental profession. The purpose of this article is to assess the safety of the products used in this bleaching technique based on results from past related research and current research. Ten percent carbamide peroxide solutions used in numerous studies have demonstrated tissue-healing properties as well as a propensity for the reduction of plaque and gingivitis. None of these clinical studies revealed any untoward or detrimental side effects, and all demonstrated beneficial effects. Although some concern exists regarding the potentiating effects of peroxide solutions in the presence of known carcinogens, concerns of toxicity or damage to hard and soft tissues appear unfounded. The majority of current and past research and literature indicates that the current use of a 10% carbamide peroxide solution in the method advocated for bleaching vital teeth is apparently safe when administered properly under the supervision of a dentist.

Effect of cementum defects on radicular penetration of 30% H2O2 during intracoronal bleaching

Bleaching pulpless teeth with 30% hydrogen peroxide has been reported to cause external cervical root resorption. It has been hypothesized that H2O2 penetrating through open dentin tubules can initiate an inflammatory reaction which could result in root resorption. Extracted human premolars were treated endodontically and bleached intracoronally using the thermocatalytic technique. The teeth were divided into three groups; one group with no cementum defects at the cementoenamel junction, one group with artificial cementum defects at the cementoenamel junction, and another group with artificial cementum defects at the middle third of the root. The radicular penetration of 30% hydrogen peroxide in the three groups was assessed directly and compared using an in vitro model. Radicular penetration of hydrogen peroxide was found in all of the groups tested. The penetration of hydrogen peroxide was significantly higher in teeth with cementum defects at the cementoenamel junction than in those without defects.

Management of a patient with severe postbleaching cervical resorption. A clinical report

This report suggests a treatment alternative for replacing a maxillary lateral incisor, and identifies the complication of cervical resorption after bleaching.

Bond strength of composite resin to enamel bleached with carbamide peroxide

Bleaching with 35 percent hydrogen peroxide causes enamel surface changes, which result in lower bond strengths of composite resin. Although a previous SEM study showed that home bleaching with 10 percent carbamide peroxide does not cause such surface changes, the results of our study indicate that carbamide peroxide bleaching reduces the shear bond strength of composite to etched enamel. Removal of surface enamel, however, restores bond strengths to normal levels.

Cervical root resorption following bleaching of endodontically treated teeth

One year following root canal treatment and internal etching and bleaching of anterior teeth in dogs, the animals were sacrificed and the teeth prepared for stereomicroscopic or light microscopic examination. Evidence of cervical root resorption and ankylosis was noted on several teeth. The bleaching factors associated with the teeth exhibiting resorption were heat with 30% hydrogen peroxide. Resorption was not related to walking bleach or to internal etching alone.

Effect of enamel microabrasion compound on human gingiva: report of a case

A new material to be used in the procedure of enamel microabrasion has been recently introduced. Because the compound contains hydrochloric acid, the manufacturer recommends many safety precautions, especially use of the rubber dam. This case report documents the effect of the enamel microabrasion compound on the gingiva of one human subject and verifies the need for careful handling of the material.

Preliminary surface analysis of etched, bleached, and normal bovine enamel

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

[Histological aspects of tooth bleaching technics]

The chemical principles of tooth bleaching are detailed in order to analyze scanning microscopy data obtained following internal and external bleaching tooth bleaching appears harmless to the enamel structure providing no etching is applied prior to bleaching. Previous enamel undermining appears to increase the porosity along preexisting cracks. Internal bleaching gives way to enamel and dentinal demineralization, which is of particular importance at the dento enamel junction. The biological effects of bleaching on dental hard tissues must be viewed in light of the clinical indications for these procedures.

The management of postbleaching cervical resorption

Cervical resorption has been repeatedly associated with intracoronal bleaching procedures. This report reviews literature associated with postbleaching resorption, a case, and a rationale for management. We observed cervical resorption upon recall of an intracoronal bleaching case. It was successfully treated with a calcium hydroxide "recalcification" procedure. Twenty-three months later, no further resorption has been observed.

Internal bleaching of discoloured teeth

Internal bleaching can be a simple, economic and effective method for improving the appearance of discoloured non-vital teeth. The authors give a step-by-step guide to the 'walking bleach' technique, and describe how to avoid the most common potential complications of bleaching.

The influence of time of hydrogen peroxide exposure on the adhesion of composite resin to bleached bovine enamel

Standard sized cylinders of a small particle light-cured resin were bonded to the flattened labial surface of young bovine incisor teeth which had been previously subjected to four different treatments: (a) immersion in 35% hydrogen peroxide and etched with 37% phosphoric acid gel for 60 s, (b) immersion in saline and etched for 60 s, (c) etched for 60 s and immersion in hydrogen peroxide, and (d) etched for 60 s and immersion in saline. Two hydrogen peroxide and saline immersion periods were used, 5 and 30 min. Specimens were stored in water at 37 degrees C for 1 and 7 days before tensile and shear testing. A total of 256 teeth were used, 8 for each treatment group, each immersion period, and each water storage period for each test. Statistical analysis of the results indicated that there was a highly significant reduction in the adhesive bond strength of the resin when the enamel was exposed to hydrogen peroxide and that the reduction was, within the limits of this study, time dependent. The bond strength was unaffected by the etching order and the period of water storage. Scanning electron microscopic examination of randomly selected fractured peroxide-treated specimens indicated that the failure occurred primarily at the bonding resin-enamel interface and that it was associated with areas of resin nonattachment and an alteration in resin quality. It is suspected that these changes were caused by the presence of residual peroxide or peroxide-related substances at or near the enamel surface.

Surgical-restorative treatment of bleaching-related external root resorption

Three teeth in 2 patients were treated after intracoronal bleaching with 30% hydrogen peroxide had resulted in external root resorption. An attempt to treat one tooth by placing an intracoronal dressing with calcium hydroxide had failed. The resorption defects were exposed surgically by reducing and re-contouring the alveolar crest. The restorations were made during the surgical procedure, with a light-cured composite in one case and with amalgam in the other, and were of compromised quality due to the difficulty of control. One year follow-up examinations revealed periodontal complications in both cases, in the form of a further resorption of the alveolar crest and gingival edema. These sequelae suggested that the restoration of bleaching-related resorption defects should have been a secondary stage, after the surgical exposure of the defects had been completed first. For the purpose of exposing the defects, the level of the alveolar crest should be reduced enough to secure a biological width from the restorations.

Cervical resorption in bleached teeth

A case of cervical resorption in a bleached, pulpless tooth is reported. The tooth has not been traumatized, and no other reason for the resorption could be found except the possible effects of a caustic bleaching agent. This case further supports the evidence in the literature that a cause-and-effect relationship exists between Superoxol bleaching and cervical resorption.