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At least 19 recordsLinked to original sources
PubMed1995

Acute toxicity of carbamide peroxide and a commercially available tooth-bleaching agent in rats.

Previous studies have indicated that tooth-bleaching agents contain potentially hazardous chemicals. The present study evaluates the acute toxicity of a commercially available tooth-bleaching agent and carbamide peroxide, which is the active bleaching ingredient. Rats were dosed by stomach gavage, i.e., via a stomach tube, with 5, 15, and 50 mg carbamide peroxide/kg body weight and 150 and 500 mg tooth-bleaching agent/kg body weight, corresponding to 15 and 50 mg carbamide peroxide/kg body weight. Animals were killed after either one or 24 h. Autopsies were performed, and the distal part of the esophagus and the stomach were removed and processed for light microscopy investigation. Liver and kidney were evaluated histologically in animals killed after 24 h. Carbamide peroxide gave dose-dependent ulcerations of the gastric mucosa, with the 15 mg/kg body weight as the lowest observed effect level. The lesions were clearly visible after one h and seemed to be healing after 24 h. The ulcerations of the gastric mucosa were more pronounced after exposure to the tooth-bleaching agent than those observed after a comparable dose of carbamide peroxide. This may be attributed to the hydrophobic gel and the content of a carbopol (which increases the tissue adherence and retards the release of oxygen) in the bleaching agent. No apparent injury was observed in livers and kidneys. An exposure limit based on the lowest observed effect level (15 mg carbamide peroxide/kg body weight) and a safety factor of 100 were established and utilized in a risk assessment which indicated that daily human exposure during a bleaching procedure may come close to or even exceed this limit.

Acrylic Resins↗
PubMed1994

Home-use tooth bleaching agents: an in vitro study on quantitative effects on enamel, dentin, and cementum.

Studies on home-use bleaching agents containing carbamide or hydrogen peroxide demonstrate minimal topographic alteration and insignificant organic change to tooth material. This in vitro study evaluated the effects of a three-step commercial home-use bleaching agent on extracted human incisors over time. Each tooth was digitized by baseline and sequential profilometry and analyzed using computer software. Statistically significant volume loss was evident in cementum and dentin after simulations of 4 and 8 weeks of use.

Citrates↗
PubMed1989

An in vitro comparison of different bleaching agents in the discolored tooth.

Extracted teeth with intact crowns were stained to compare and evaluate the effectiveness of four bleaching agent combinations. Forty-two permanent and 12 deciduous teeth were used. The bleaching agents were placed into coronal pulp chambers and then evaluated and rated at 1-, 3-, 7-, and 14-day and 6-month intervals. New sodium perborate combined with fresh Superoxol was the most effective bleaching agent with 93% success (the final shade was as light as the prestained shade). New sodium perborate and 1-yr-old Superoxol was 73% successful. New sodium perborate with distilled water and old sodium perborate with distilled water were both 53% successful. Deciduous teeth demonstrated a response to bleaching agents similar to that of permanent teeth. Color regression after 6 months was found in 4% of the cases. When it occurred, the degree of color regression was minimal.

Borates↗
PubMed2026

Influence of Immediate Post-Bleaching Polishing on Enamel Color, Morphology, and Sensitivity: A Randomized Clinical Trial.

OBJECTIVE: This study evaluated the influence of polishing on enamel color change after in-office bleaching treatment on tooth morphology and sensitivity. MATERIALS AND METHODS: A total of 50 volunteers were randomized into two groups (n = 25): in-office bleaching with 35% hydrogen peroxide gel for 45 min without polishing (GSEM) or with polishing (GP). Color analysis was performed four times, at the beginning of the starting line and immediately after the first, second, and third bleaching sessions with a spectrophotometer. A qualitative analysis of enamel morphology was performed under a scanning electron microscope. Tooth sensitivity was assessed daily using the Visual Analog Scale (α = 0.05). RESULTS: There was no statistically significant difference (p > 0.05) in tooth color change when comparing ΔE, ΔE00, and ΔWID between the groups. The enamel surface showed larger areas of irregularities and depressions in the GP group than in the GSEM group. There was no difference in tooth sensitivity (p > 0.05) between the groups. CONCLUSIONS: Polishing after whitening in the office does not change the color and sensitivity of the tooth but promotes greater changes in the morphology of the enamel, such as increased surface roughness. CLINICAL RELEVANCE: Polishing immediately after teeth whitening causes greater changes in enamel surface morphology.

Humans↗
PubMed1989

[Bleaching of discolored teeth. Examination and evaluation of the effect of various bleaching agents].

Many patients suffer from tooth discoloration, a condition that produces more psychological distress than generally thought, especially when the anterior teeth are involused. In this study, tests were carried out to determine the effect of various agents applied discolored teeth for bleaching. Blood, colored tissue fluids I and II, attached to filter papers after being naturally exposed for a week were selected as object bleaching. Each subject was soaked in 30% hydrogen peroxide solution (30%H2O2), 3% hydrogen peroxide (3%H2O2), sodium hypochlorite solution (NaOCl), sodium perborate (NaBO3) and combination of them, then effect of agents were observed according to time-lapse. The following results were obtained. 1. NaOCl was most effective. 2. The action of 3%H2O2 was slow, showing only a slight bleaching effect after one week. 3. NaBO3 alone did not have any bleaching effect.

Borates↗
PubMed1989

Tubular permeability to calcium hydroxide and to bleaching agents.

Recent reports of clinical cases suggest that cervical root resorption may follow bleaching of endodontically treated teeth. Inflammatory root resorption may be arrested by placement of calcium hydroxide into the root canal. The dentinal tubules are assumed to be a possible route of action for both agents. pH Values of the medium surrounding the tooth after placement of bleaching agents and calcium hydroxide within the root canals were determined in this study. Thirty extracted single-rooted human teeth were divided into three equal groups. The pulp cavity of the experimental teeth was filled with either bleaching agents or calcium hydroxide. In the control group it was left empty. Dipping in paraffin sealed the access cavity and the apical foramina and isolated the teeth except at the cervical root surface. The teeth were placed in vials containing distilled water and the pH of the medium was measured after 1 h, 3 days, and 7 days following renewal of the medium. The level of the pH in the first group increased, indicating that the bleaching agents leaked from the root canal to the medium surrounding the teeth. The pH in other two groups did not change noticeably. The results suggest that bleaching agents may leak from the root canal toward the periodontal tissues but calcium hydroxide does not alkalinize the medium surrounding the teeth. Leakage of the bleaching agents through dentin may, therefore, be considered as a possible etiological factor that initiates an inflammatory process around the teeth that may be followed by cervical root resorption.

Calcium Hydroxide↗
PubMed1992

Vital tooth bleaching: review and current status.

Vital tooth bleaching refers to the clinical application of a chemical solution to a tooth surface in order to achieve a lightening effect. This article reviews the available literature to address the following questions: What are the methods of vital bleaching? How does vital bleaching work and is it effective? What effects are there on the teeth, dental restorative materials, soft tissues and systemic health? The techniques used in the application of dentist-applied and patient-applied bleaching systems are described. Generally, vital tooth bleaching has been found to be effective, however, relapse does occur. The literature suggests that bleaching agents may have transient effects on the tooth itself, and may affect some dental materials. Soft tissues exposed to hydrogen peroxide for prolonged periods show changes consistent with inflammation or hyperplasia. Hydrogen peroxide may also potentiate the carcinogenic effect of known carcinogens. However, more clinically relevant studies are needed. Until long-term safety data becomes available, the dental practitioner should approach the use of in-home bleaches with caution. The U.S. Food and Drug Administration (FDA) recently classified these products as "new drug." However, dentist-applied bleaching gel systems are a viable alternative and deserve further consideration. They are simple to use, require little armamentarium, and limit the exposure of the bleaching agent to the teeth only. Vital tooth bleaching refers to the clinical application of a chemical solution to a tooth surface in order to achieve a lightening effect. There was a resurgence of interest in vital bleaching with the recent introduction of the in-home bleaching technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbamide Peroxide↗
PubMed1993

Acute toxicological effects of ingested tooth whiteners in female rats.

Tooth whiteners are considered as cosmetic agents to be used for bleaching teeth. Since tooth whitener may be swallowed during the whitening procedure, studies were conducted to determine whether ingestion of tooth whitener containing carbamide peroxide resulted in toxic effects. Adult female rats were used, and vaginal smears were examined daily to determine whether the animals were ovulating. Following an overnight fast, a single bolus of a commercial tooth whitener (5 g of tooth whitener/kg fasting body weight) was administered by gavage. Control rats received de-ionized water. After 2 h, mean respirations per min of animals receiving the tooth whitener Quik Start (contains 35% carbamide peroxide) decreased from 169 to 55, and body temperature decreased from 38.4 to 34 degrees C. Other distress signs included: labored breathing, loss of righting reflex, partial eye closure, bloody urine, and incontinence. Three of 22 animals (3/22) died within 48 h, of gastric hemorrhaging. Eight/10 rats stopped ovulating. At necropsy 2 weeks post-dosing, 10/19 animals had grossly bloated stomachs, and mucosal necrosis was observed histologically in 3. Animals receiving White & Brite or Nu-Smile (containing 10 or 15% carbamide peroxide, respectively) exhibited similar but milder symptoms. The data indicate that ingestion of large doses of commercial preparations of tooth whiteners may be acutely toxic, sometimes fatal, to female laboratory rats.

Animals↗
PubMed1995

Role of saliva and salivary components as modulators of bleaching agent toxicity to human gingival fibroblasts in vitro.

Mild oxygenating agents generating H2O2 are used for effective at-home tooth bleaching, but can cause gingival ulcers in some patients. There are concerns about the possible pathological effects of relatively long-term exposure of oral tissues to bleaching agents. Previous work in our laboratory showed that a bleaching agent, which generates approximately 3% H2O2 from carbamide peroxide, was toxic to human gingival fibroblasts in vitro, but that the toxicity was abolished by treatment with the H2O2-destroying enzyme catalase. The purpose of the present study was to determine if whole saliva, the salivary enzyme lactoperoxidase (LP) (which, like catalase, removes H2O2), or salivary mucin protected fibroblasts from bleaching agent toxicity. The cells were exposed to 0.05% agent with or without saliva, LP, mucin or catalase (as a positive control based on our previous study) and assessed for effect on viability/morphology (by microscopic observation), proliferation (by [3H]-thymidine incorporation), and the production of fibronectin (FN) and type I collagen (by ELISA). While the bleaching agent at 0.05% caused cell death, the cells appeared viable and morphologically normal when treated with the bleaching agent and LP (> or = 0.1 microM), saliva LP, and catalase from agent inhibition of proliferation (P < or = 0.04) and FN production (P < or = 0.01). Mucin had statistically insignificant or no protective effect as assessed by the above parameters. Treatment with saliva, LP, mucin, and catalase gave complete or partial protection from agent-inhibition of collagen production (P < or = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Catalase↗
PubMed1993

Toxicity of two carbamide peroxide products used in nightguard vital bleaching.

This study evaluated the effects of two generic classes of 10% carbamide-peroxide (CP) oxygenating agents (currently under clinical assessment for nightguard vital tooth bleaching) for lethality and genetic mutation after oral administration to mice, and for cellular cytotoxicity to mouse fibroblasts in vitro. The single dose LD50 values for a non-carbopol-containing CP (Gly-Oxide) and a carbopol-containing CP (Proxigel) in mice were found to be 143.8 mg/kg and 87.2 mg/kg, respectively. Genotoxicity, as measured by the Mouse Micronucleus test for mutagenicity, was negative for both 10% CP agents in comparison with positive and negative controls. Cytotoxicity as measured in the L929 fibroblast lysis assay resulted in 50% killing of L929 fibroblasts at 0.62 for the non-carbopol-containing CP and 1.88 mmol/L for the carbopol-containing CP. Both 10% CP agents were compared with seven widely-used dental products in the L929 fibroblast lysis assay and found to be no more toxic than these products.

Analysis of Variance↗
PubMed1992

Adverse response to vital bleaching.

A case study is presented that described an acute flare-up of a tooth following a vital bleaching procedure. The case illustrates (a) the importance of assessing the pulpal and periradicular status of a tooth prior to any vital bleaching procedure; and (b) the alteration of the local adaptation syndrome by the bleaching agent.

Adult↗
PubMed1992

Advances in the treatment of acquired and developmental defects of hard dental tissues.

With the decline in dental caries, the dental profession and the general public have become sensitized to the "new" specialty of cosmetic dentistry. As a consequence, research in the field of dental materials for the ideal, most natural restorative materials and techniques has become a primary focus and has had a profound influence on dental education and practice. This brief article will highlight some of these newer concepts.

Composite Resins↗
PubMed1990

Whitening agents.

Explore the source record for details and available documents.

Esthetics, Dental↗
PubMed1994

Effect of hydrogen peroxide and sodium perborate on the microhardness of human enamel and dentin.

The effect of 30% hydrogen peroxide and a paste of sodium perborate mixed with hydrogen peroxide at different temperatures and time intervals on the microhardness of human enamel and dentin was examined. Intact extracted human teeth were sectioned, embedded in acrylic resin, polished, and divided into four test groups related to surface treatment. The groups were 30% hydrogen peroxide at 37 degrees C, 30% hydrogen peroxide at 50 degrees C in an illuminated chamber, a paste of sodium perborate mixed with hydrogen peroxide at 37 degrees C, and a paste of sodium perborate mixed with hydrogen peroxide at 50 degrees C in an illuminated chamber. Teeth treated with distilled water at either 37 degrees C or 50 degrees C served as controls. The results indicated that treatment with 30% hydrogen peroxide reduced the microhardness of both enamel and dentin. This reduction was statistically significant after 5-min treatment for the dentin and after 15-min treatment for the enamel (p < 0.05). Treatment with sodium perborate mixed with hydrogen peroxide did not alter the microhardness of either the enamel or dentin at the tested temperatures and time intervals. It is therefore suggested that the use of high concentrations of hydrogen peroxide for bleaching purposes should be limited. Sodium perborate appears to be a less damaging bleaching agent.

Borates↗
PubMed1992

Effect of cervical coating of ethyl cellulose polymer and metacrylic acid copolymer on the radicular penetration of hydrogen peroxide during bleaching.

Extraradicular leakage of oxidizing agents during bleaching is an undesirable event and thus need to be prevented. The effect of external cervical coating of ethyl cellulose (EC) and metacrylic acid copolymer (MAC) on the radicular penetration of hydrogen peroxide during intracoronal bleaching was examined. Single rooted human premolars extracted for orthodontic reasons were used. The cementum covering the cemento-enamel junction was mechanically removed and the teeth treated endodontically and bleached with 30% hydrogen peroxide. Radicular hydrogen peroxide penetration was measured before coating the teeth and after applications of 1-3 layers of EC or 3 layers of MAC external cervical coatings. It was found that the radicular penetration of 30% hydrogen peroxide was related to the number of layers of cervical EC coatings. Application of one layer of EC did not reduce the hydrogen peroxide penetration. Two and three layers of EC reduced the hydrogen peroxide penetration by 38% and 85% respectively. Three layers of MAC reduced the radicular hydrogen peroxide penetration in 83%. Statistically, a highly significant difference was found between the teeth coated with three layers of either EC or MAC and the noncoated teeth (p < 0.001). It was concluded that application of ethyl cellulose or metacrylic acid copolymer to exposed cervical root surfaces may effectively prevent extraradicular leakage of bleaching agents.

Cellulose↗