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PubMed1998

Intradermal irritation of dental bleaching agents in rats.

AIM: To evaluate the irritative potential of three dental bleaching agents (hydrogen oxide, carbopol, and carbamide peroxide). METHODS: In rats, Evans blue (2.5%, 1 mL.L-1) was injected i.v. and later each test solution was injected intradermally on the back. After the concentration of the dye in the stained skin area was determined by spectrophotometric analysis. RESULTS: All the dental bleaching agents caused increase of vascular permeability and the intensity varied with the time. CONCLUSION: Dental bleach agents had a great potential for irritating soft tissues.

Acrylic Resins↗

PubMed2001

Effects of 10% carbamide peroxide bleaching materials on enamel microhardness.

PURPOSE: To evaluate the microhardness of enamel treated with two different 10% carbamide peroxide bleaching materials at different time intervals. MATERIALS AND METHODS: Two bleaching agents were analyzed: Opalescence (OPA) and Rembrandt (REM). The control group (CON) consisted of dental fragments maintained in artificial saliva. Bleaching was accomplished for 8 hrs per day and stored during the remaining time in an individual recipient with artificial saliva. Enamel microhardness testing was performed before the initial exposure to the treatments and after 1, 7, 14, 21, 28, 35 and 42 days. RESULTS: The ANOVA, followed by the Bartlet and Tukey tests, showed significant differences for treatments (P < 0.00001) from day 7-day 42. From the 7th to the 14th day, OPA presented an increase of enamel microhardness over time while REM presented a decrease of microhardness. Statistical differences were not found between REM and the control group (OPA > CON = REM). From the 21st-35th day, enamel fragments bleached with OPA and REM presented a decrease of microhardness. Statistical differences of microhardness were verified among all the treatments (OPA > CON > REM). On the day 42, statistical differences were not found between OPA and the control group, but they were found between REM and the control group (OPA = CON > REM). The polynomial regression showed an increase of microhardness for OPA until the 21st day, followed by a decrease of microhardness up to the 42nd day. A decrease of microhardness for REM was verified. There were alterations in enamel microhardness as a function of bleaching time when using the two different 10% carbamide peroxide whiteners. Over a 42-day treatment time, bleaching with REM agent caused a decrease in enamel microhardness. The OPA agent initially increased the microhardness, then returned to the control level. Different bleaching materials with the same concentration of carbamide peroxide have different effects on the enamel.

Analysis of Variance↗

PubMedDate not supplied

Comparative study of the effects of two bleaching agents on oral microbiota.

This study evaluated the in vivo effects of bleaching agents containing 10% carbamide peroxide (Platinum/Colgate) or 7.5% hydrogen peroxide (Day White 2Z/Discus Dental) on mutans Streptococcus during dental bleaching. The products were applied on 30 volunteers who needed dental bleaching. In each volunteer, one of the two bleaching agents was used on both dental arches one hour a day for three weeks. Analysis of the bacterial counts was made by collecting saliva before (baseline values), during (7 and 21 days) bleaching treatments and 14 days posttreatment. The Friedman non-parametric analysis (alpha=0.05) found no differences in microorganism counts at different times for each group for both agents (p>0.05). The Mann Whitney nonparametric test (alpha=0.05) showed no differences in micro-organism counts for both agents (p>0.05). Different bleaching agents did not change the oral cavity mutans Streptococcus counts.

Adolescent↗

PubMed1994

Bleaching vital teeth.

This year is approximately the fifth year of controlled bleaching of vital teeth administered by the patient, and this practice still generates a great deal of discussion by the American Dental Association, the US Food and Drug Administration, the media, and general practitioners. The placement of a plastic carrier intraorally to hold a carbamide peroxide gel in the mouth is referred to as passive bleaching or dentist-prescribed home bleaching. This article reviews the past year's research, which contains many opposing opinions in both in vitro and in vivo studies with respect to the effect of carbamide peroxide on the hard and soft tissues when they come into contact with this agent for various lengths of time. Above all, the question of safety still arises, although few if any adverse effects have been reported with the use of dentist-prescribed, patient-applied home bleaching. Five years of nonproblematic treatment for millions of patients leads many dentists to believe that this technique, when controlled by the dentist, serves the public well.

Carbamide Peroxide↗

PubMed2004

Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentine.

The purpose of this study was to compare the effect of traditional and alternative bleaching agents on microhardness of human dentine when used intracoronally. Thirty-six premolars were divided into six groups and bleaching agents were sealed into the pulp chambers as follows: group 1--distilled water (control), group 2--30% hydrogen peroxide solution, group 3--sodium perborate mixed with distilled water, group 4--sodium perborate mixed with 30% hydrogen peroxide solution, group 5--35% carbamide peroxide gel, group 6--35% hydrogen peroxide gel. Access cavities were sealed and the teeth were stored in distilled water at 37 degrees C. After 7 days, each tooth was sectioned at the cemento-enamel junction level and microhardness testing was carried out on dentine. The results showed that treatment with 35% hydrogen peroxide gel, 30% hydrogen peroxide solution and 35% carbamide peroxide gel reduced the microhardness of outer dentine to a small extent while treatment with sodium perborate mixed with water and sodium perborate mixed with 30% hydrogen peroxide solution did not significantly alter the microhardness of dentine.

Antioxidants↗

PubMedDate not supplied

At-home bleaching system: effect on gingival tissue.

This study evaluated the effects of an at-home vital bleaching system on gingival responses over a 6-week period. Objective measures were utilized to measure and monitor gingival inflammation over this period of time. Vital bleaching was performed as follows: (1) bleaching gel in a prefabricated mouthguard and (2) an ad-mix technique--bleaching gel and toothpaste in a 1:1 ratio. In addition a control group used a placebo in a prefabricated mouthguard. The at-home vital bleaching system produced no adverse gingival tissue responses. Furthermore, the at-home vital bleaching system helped produce a therapeutic effect on inflamed gingival tissues over the course of the study.

Adult↗

PubMedDate not supplied

Effect of bleaching gels on the surface roughness, hardness, and micromorphology of composites.

This study sought to evaluate the effect of three bleaching gels on the surface roughness, hardness, and morphology of resin-based composites basically designed for posterior and anterior use. The application of the bleaching agents tested had no statistically significant effect on the surface roughness or hardness of the composites tested. With both unbleached and bleached samples, the posterior composite was significantly harder than the anterior composite while the roughness was not significantly different (p > 0.06).

Carbamide Peroxide↗

PubMed2001

Occurrence and management of dental fluorosis.

The prevalence of dental fluorosis is on the increase in different parts of the world, even in areas with fluoride-deficient public water supplies. This may be due to increased use of fluoride in preventive dentistry. In some countries, exposure to apparently low fluoride concentrations in drinking water has resulted in severe dental fluorosis in some children. This underscores the importance of taking into consideration all sources of fluoride intake in a community before prescribing fluoride supplements or recommending appropriate fluoride concentration for the public water supply. Preventive management of dental fluorosis includes de-fluoridation of drinking water in endemic areas, cautious use of fluoride supplements and supervision of the use of fluoride toothpaste by children aged below 5 years. Aesthetically objectionable discolouration of fluorosed teeth may be managed by bleaching, micro-abrasion, veneering or crowning. The choice between these treatments depends on the severity of the fluorosis and this may be satisfactorily determined by the Thylstrup and Fejerskov index.

Adolescent↗

PubMed2004

Effect of home bleaching agents on the roughness and surface morphology of human enamel and dentine.

AIMS: Carbamide peroxide (CP) containing bleaching agents are now widely used in different concentrations. In this study, the effect of 10% and 15% CP containing home bleaching agents on the surface roughness and morphology of human enamel and dentine were evaluated in vitro. METHODS: 90 non-carious human mandibular incisors were divided randomly into two equal groups (enamel and dentine). The dentine group specimens were ground to expose dentine surfaces. The samples in both groups were then randomly divided into three main groups and then divided into three subgroups, according to bleaching application times (n=15). The samples in both enamel and dentine groups were treated with 10% CP at Group 1 and 4, 15% CP at Group 2 and 5 and distilled water at Group 3 and 6. The surface roughness of the samples was analysed before bleaching (1a, 2a, 3a for enamel, 4a, 5a, 6a for dentine), after 4hr (1b, 2b, 3b for enamel, 4b, 5b, 6b for dentine) and after 28hr of bleaching application (1c, 2c, 3c for enamel, 4c, 5c, 6c for dentine) using a computerised roughness tester. The surface morphologies of treated and control specimens were also examined by SEM. RESULTS: There were no statistically significant differences between the surface roughness of untreated control specimens and the specimens treated with the bleaching materials (10% and 15% CP) for both enamel and dentine at any given measurement time (p>0.05). CONCLUSION: Under the careful guidance of a dentist, home bleaching can be thought a reliable treatment for both stained enamel and dentine, regardless of whether 10% or 15% CP is used.

Adult↗

PubMed1994

Salivary pH changes during 10% carbamide peroxide bleaching.

The purpose of this study was to evaluate the effect on salivary pH of a 10% carbamide peroxide solution when used with a custom-fitted guard for bleaching teeth. Baseline pH values were established for unstimulated saliva and on saliva produced while wearing an empty guard. After insertion of a guard half filled with Proxigel, salivary pH measurements were made at 5-minute intervals until the values returned to baseline levels. Mean salivary pH values were 6.81 +/- 0.11 for unstimulated samples and 6.91 +/- 0.18 after insertion of the empty guard. After insertion of the filled guard, there was a statistically insignificant decrease in salivary pH during the first 5 minutes, followed by an increase above baseline at 10 minutes, to a mean peak value of 7.32 +/- 0.27 at 15 minutes. The difference between the baseline values and the mean peak value at 15 minutes was statistically significant. The results of the study indicated that the pH of saliva increased significantly during the first 15 minutes of nightguard vital bleaching and did not significantly drop below baseline in the first 2 hours after insertion with a moderately low-pH solution.

Adult↗

PubMed2005

Assessment of genetic damage induced by dental bleaching agents on mouse lymphoma cells by single cell gel (comet) assay.

Dental bleaching is a simple and conservative procedure for aesthetic restoration of vital discoloured teeth. However, dental bleaching agents may represent a hazard to human health, especially by causing DNA strand breaks. Genotoxicity tests form an important part of cancer research and risk assessment of potential carcinogens. In the current study, the genotoxic potential associated with exposure to dental bleaching agents was assessed by the single cell gel (comet) assay in vitro. Six commercial dental bleaching agents (Clarigel Gold - Dentsply; Whitespeed - Discus Dental; Nite White - Discus Dental; Magic Bleaching - Vigodent; Whiteness HP - FGM and Lase Peroxide - DMC) were exposed to mouse lymphoma cells in vitro. The results pointed out that all dental bleaching agents tested contributed to the DNA damage as depicted by the mean tail moment. Clear concentration-related effects were obtained for DNA damaging, being the strongest effect observed at the highest dose of the hydrogen peroxide (Whiteness HP and Lase Peroxide, at 35% concentration). On the contrary, Whitespeed (Discus Dental) induced the lowest level of DNA breakage. Taken together, these results suggest that dental bleaching agents may be a factor that increases the level of DNA damage as detected by the single cell gel (comet) assay.

Animals↗

PubMedDate not supplied

Influence of bleaching agents and desensitizing varnishes on the water content of dentin.

This in vitro study investigated the possible dehydration of dentin caused by bleaching agents. Furthermore, it tested whether protective dentin varnishes can maintain the physiological moisture of dentin during bleaching treatment. Fifty-five standardized dentin cylinders were prepared from freshly extracted bovine incisors under constant water irrigation. Prior to bleaching, the treatment specimens were conditioned at room temperature in a hygrophor for 14 days. The samples were divided into 11 groups. The Group A specimens, which were completely dehydrated, and Group B, which was stored for 2 weeks in a hygrophor, served as controls (A, B n=5). The other samples (n=10 each group) were coated with Vivasens [VS] (C), Bilfuorid [BF] (D) and Seal&Protect [SP] (E). Five specimens from each group (C-E) were subsequently treated with an experimental bleaching gel (Exp BG) (20% carbamide peroxide [CP], glycerine-based gel): Cb, Db, Eb. The remaining specimens were bleached with Exp BG (F) only, Vivastyle (G: 16% CP, glycerine-based gel) or Vivastyle Paint On (H: 6% CP-varnish) for 7 days (n=5 each group) with bleaching time for gels: 2 hours/day, paint on: 20 minutes/day. After the respective treatments, the overall water content of each specimen was determined using the analytical method of Karl-Fischer-titration. The water content of bovine dentin (Group B, mean%+/-SD) obtained in this study amounted to 15.24+/-0.4. All bleaching products significantly reduced the water content compared to the controls (exp BG: 13.32+/-0.47, Vivastyle 13.2+/-0.27, paint on 13.72+/-0.54; p<0.05). Also, application of SP before bleaching resulted in reduced water content (14.06+/-0.12; p=0.0005). However, bleaching with exp BG following use of VS (14.99+/-0.42) or SP (13.85+/-0.26) did not result in a reduction of water content in dentin. Pretreatment with BF did not protect dentin from water loss during bleaching (12.44+/-0.38; bi p=0.0009). All glycerine-based bleaching products used in this study had a significant dehydrating effect on dentin. The application of protective varnishes prior to bleaching treatment may reduce or even prevent dentin dehydration.

Animals↗

PubMed2006

Surface change of dental amalgam after treatment with 10% carbamide peroxide.

The aim of this study was to explore the effect of bleaching agents on the release of metal ions and change in physical and chemical characteristics of amalgams. Amalgam surface changes resulting from bleaching on amalgam were assessed with inductively coupled plasma atomic emission spectrophotometer, an automatic mercury analyzer, a colorimeter, and atomic force microscopy. Analysis of the release of metal ions indicated that the bleaching agent caused more copper, tin, and mercury ions to be released into the immersion solution. Furthermore, metal ion release increased progressively as immersion time was increased from 42 to 84 hours. Morphological examination revealed no significant effects of the 10% carbamide peroxide bleaching agent on the surface morphology of any of the amalgams tested. These results demonstrated that bleaching using 10% carbamide peroxide did not adversely affect the two types of amalgam tested. In other words, a 10% carbamide peroxide bleaching agent can be safely used on a short-term basis in dentist-monitored bleaching of the dental amalgam.

Analysis of Variance↗

PubMed2002

Effects of carbamide peroxides on wear resistance and color change of enamel opposing porcelain.

PURPOSE: This study evaluated the effects of a simulated 1- and 2-week night guard bleaching technique using various bleaching gel concentrations on wear resistance and color change of human enamel opposing a feldspathic porcelain substrate. MATERIALS AND METHODS: VMK 68 feldspathic porcelain was formed into 15-mm disks (n = 63) and fired according to manufacturer's recommendations. Enamel cusps were formed and shaped from extracted third molars and treated with 1 of 3 bleaching materials for 7 or 14 days. Specimens were kept at 37 degrees C in 100% humidity. The control group was subjected to identical conditions but with water replacing the bleaching gel between and during bleaching treatments. After simulated bleaching, the enamel cusp specimens were subjected to 3-body wear testing opposite a highly polished porcelain substrate. Enamel wear was evaluated using optical scanning methods, and color was measured with a small-aperture colorimeter. Data were subjected to a one-way repeated- measure analysis of variance and various post hoc statistics. RESULTS: Results indicated that the within effect of treatment time (7 or 14 days) did not significantly affect (p = 0.13) the size of the resulting enamel wear facet, whereas the between effect of bleaching concentration was significant (p = 0.01). Statistical analysis of unbleached control groups suggests that between-group differences can be explained by variations in wear rates of the 3 enamel groups, not by the concentration differences in bleaching gels. All bleaching treatments resulted in significant color changes (p = 0.04) compared to the unbleached control, but the bleach concentration did not significantly influence the magnitude of color change (p = 0.81). CONCLUSIONS: A simulated night guard vital bleaching treatment of 1 or 2 weeks had no significant effect on the wear resistance of human enamel in vitro. The increased bleaching treatment time and concentration did not significantly affect the amount of enamel color change.

Aluminum Silicates↗

PubMed1992

Effect of peroxide bleaches on resin-enamel bonds.

Human third molar teeth were divided into three groups: untreated control; enamel treated with 35% hydrogen peroxide for 2 hours; and enamel treated with 10% carbamide peroxide gel for 14 days. All teeth were ground to present a flat enamel surface, to which cylinders of light-cured composite resin were bonded. Shear bond strengths were determined for each specimen. The mean shear bond strengths of resin-enamel bonds after pretreatment with both 35% hydrogen peroxide and 10% carbamide peroxide were significantly lower than those for untreated controls. External bleaching with these materials prior to resin bonding procedures may reduce the quality of resin-enamel bonds.

Acrylates↗

PubMedDate not supplied

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.

Acid Etching, Dental↗

PubMed1993

Characterization of enamel exposed to 10% carbamide peroxide bleaching agents.

The purpose of this investigation was to evaluate the effect of three 10% carbamide peroxide bleaching agents on enamel microhardness and surface morphology. Seventy-two enamel slabs were subjected to one of three carbamide peroxide solutions or an artificial saliva solution for 15 hours a day for 2- and 4-week periods. During the remaining 9 hours, slabs were exposed to human saliva in vivo. Although differences were not statistically significant, microhardness values of all treated specimens 2 weeks after treatment were less than those of control specimens. These trends, however, were not evident at 4 weeks. Scanning electron microscopic evaluation revealed significant surface alterations in enamel topography for slabs treated with the bleaching solutions for 4 weeks. The most severe alterations were found in slabs exposed to the lower-pH solutions.

Adult↗

PubMed2004

Effect of nonvital bleaching with 10% carbamide peroxide on sealing ability of resin composite restorations.

AIM: To (i) determine the effect of nonvital bleaching with 10% carbamide peroxide on the sealing ability of resin composite restorations bonded with a self-etching adhesive system; and (ii) compare the effects of antioxidant treatment and delayed restoration after bleaching on marginal seal. METHODOLOGY: Forty-eight noncarious maxillary incisors were divided into four groups (n=12) after conventional root canal treatment was completed. In group 1, access cavities were restored with a self-etching adhesive system and resin composite. In the remaining three groups, 10% carbamide peroxide bleaching gel was placed into the access cavities for periods of 8 h per day for 1 week. They were then restored in the same manner as group 1. Group 2 consisted of specimens restored immediately after bleaching. Group 3 specimens were treated with the antioxidant, 10% sodium ascorbate, whereas group 4 specimens were immersed in artificial saliva for 1 week before restoration. Ten specimens in each group were then subjected to dye leakage; the remaining 2 specimens were examined in a SEM (Jeol/JSM 5200, Tokyo, Japan). The dye penetration was assessed with the standard scoring system. Statistical analysis was carried out using the Kruskal-Wallis and the Mann-Whitney tests. RESULTS: Groups 1, 3 and 4 exhibited similar leakage patterns and significantly less leakage than group 2 (P<0.0083). SEM examination of groups 1, 3 and 4 specimens demonstrated close adaptation of resin composite to cavity walls, whereas group 2 specimens did not. CONCLUSION: Nonvital bleaching with 10% carbamide peroxide adversely affected the immediate sealing ability of resin composite restoration; both 10% sodium ascorbate treatment and a 1-week delay in restoration following bleaching improved the reduced sealing ability of resin composite.

Antioxidants↗