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At least 847 records · Page 47Linked to original sources

PubMed2007

Evaluation of dentin permeability after light activated internal dental bleaching.

The aim of this in vitro study was to assess quantitatively the dentin permeability of human teeth after intracoronal bleaching therapy with 35% hydrogen peroxide activated by LEDs, halogen lamp or using the walking bleach technique. Forty human maxillary central incisors had standard access cavities performed and the cervical thirds of the canals were prepared with Gates-Glidden drills up to a size 130. Roots were resected between the coronal and middle thirds and the apical portions were discarded. A glass ionomer, 2 mm thick cervical plug was placed inside the canal, at the cement-enamel junction level. Group I received 35% hydrogen peroxide gel activated by LEDs. Group II was submitted to 35% hydrogen peroxide gel activated by halogen lamp. Group III received 35% hydrogen peroxide gel and the walking bleach technique was followed. Group IV (control) received a dry cotton pellet inside the pulp chamber with temporary restoration. Dentinal permeability was quantified by copper ion penetration. Linear measurements were obtained by analysis of digital images under x 5 magnification. Mean values and SD for the experimental groups were: I, 7.1% (+/-3.2%); II, 8.4% (+/-3.0%); III, 9.1% (+/-3.0%); IV, 1.3% (+/-2.8%). One-way ANOVA was used to analyze the results. Results showed an increase of permeability values for groups I, II and III when compared to group IV (control); however, no statistical differences were found between the three tested bleaching techniques. It can be concluded that 35% hydrogen peroxide activated by LED, halogen lamp or used following the walking bleach technique produced similar increase in dentinal permeability.

Dental Pulp Cavity↗

PubMedDate not supplied

Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology.

The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect--10% carbamide peroxide (10% CP), Colgate Platinum--10% CP, Day White 2Z--7.5% hydrogen peroxide (7.5% HP), Whiteness Super--3% CP, Opalescence Quick--35% CP and Whiteness HP--35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM). Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%), and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.

Carbamide Peroxide↗

PubMed2003

[Evaluation methods of nightguard teeth bleaching with opalescence (ultradent) based on clinical and experimental tests].

In March 1989 Haywood and Heymann presented a new method for bleaching teeth called by them "nightguard vital bleaching". This procedure requires that the patient wears for 6 to 8 hours an individually designed guard filled with a viscous solution of carbamide peroxide. The aim of the present study was to determine the efficiency of the guard bleaching method and to address frequently asked questions concerning local complications and the influence of the preparation on the enamel surface. The scanning electron microscope was used in the experimental part to reveal changes in microhardness and on the surface of the bleached human enamel. The purpose of the clinical part was to determine the efficiency of bleaching, to estimate the frequency of pain and other symptoms and to check the influence of bleaching guard on accumulation of dental plaque and gingival status as reflected by the Plaque Index (Pl.I.) and the Gingival Index (G.I.). It was found that bleaching with 10, 20 or 35% carbamide peroxide reduced the microhardness and modified the morphology of enamel surface proportionally to the concentration of the bleaching agent. It was ascertained that 10% carbamide peroxide effectively bleached teeth and considerably improved the hygiene of the oral cavity and gingival status (Pl.I, G.I.). During bleaching, over half of the patients suffered from local complications--thermal hypersensitivity of teeth and irritation of gums. Some deterioration of the bleaching effect was observed after 12 months in females only. Almost 100% of the patients were satisfied with the results of bleaching and would recommend this procedure to family members.

Acid Etching, Dental↗

PubMed2004

Diode laser-activated bleaching.

This study describes a preclinical investigation with laser-activated bleaching agent for discolored teeth. Bleaching techniques involve a broad-spectrum approach utilizing hydrogen peroxide (3-38%) with or without heat or laser, carbamide peroxide (10-30%), or a mixture of sodium perborate and hydrogen peroxide. Extracted human maxillary central incisors were selected. In the bleaching experiment, 38% hydrogen peroxide was used. Two different laser systems and light emission diodes for activation of the bleaching agent were used: diode laser, wavelength 970 nm, and infra-red diode laser, wavelength 790 nm, with eight blue light emission diodes, wavelength 467 nm. The enamel surface was evaluated with the scanning electron microscope. The method of chemical oxidation resulted in a 2-3 shade change in one treatment (15 min). Shorter time (5 min) was not effective. The diode laser, wavelength 970 nm, and the bleaching agent produced the same effect but with a shorter time of bleaching process (5 min - 1 W, 2.5 min - 2 W). Infra-red diode laser, wavelength 790 nm with eight blue light emission diodes, wavelength 467 nm, and the bleaching agent reached the desired color shade also after a shorter time (5 min - 40 mW). Slight surface modification after the bleaching process was detected with scanning electron microscopy. Currently, the laser has been proven the most valuable energy source for power bleaching with simple and short application in the dental office.

Hydrogen Peroxide↗

PubMed1992

Alterations in human enamel surface morphology following vital bleaching.

Extracted intact human teeth (n = 4) were treated for 30 days by three protocols: Home 1 (Proxigel, n = 4) for 8 hours daily, Home 2 (White & Bright, n = 4) for 24 hours with 3 minutes of stannous fluoride gel, or an Office protocol (n = 4) using 30% hydrogen peroxide (Superoxol) warmed by a high-intensity light while the controls remained untreated. "Home" bleaching agents contain approximately 10% carbamide peroxide. After treatment, the coronal surfaces were examined with a scanning electron microscope (SEM) at 2000 power magnification, and the surface topography was measured by a profilometer. The SEM photomicrographs of the controls and office-treated groups were similar to previously reported descriptions, while the home bleached surfaces appeared similar to each other. Profilometric analysis was used to examine surface roughness and surface waviness. Mean surface roughness in microns was: control, 1.9; Home 1, 0.6; Home 2, 0.9; and Office, 0.6. Surface waviness was ranked control > office > Home 1 = Home 2. Enamel surface alterations were evident after the three bleaching methods. The differences between the office and home-treated surfaces were unrelated to the pH of the bleaching agents.

Carbamide Peroxide↗

PubMed1993

Bleaching: is it safe and effective?

It has been well documented that bleaching whitens teeth, but has its safety been documented? This paper reviews bleaching's predictability, esthetics, longevity, and side effects. A discussion of the bleaching reaction on teeth and soft tissue raises concerns over the safety of the procedure.

American Dental Association↗

PubMed2004

Effect of bleaching on restorative materials and restorations--a systematic review.

OBJECTIVE: Internal and external bleaching procedures utilizing 3-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents, such as carbamide peroxide or sodium perborate, can be used for whitening of teeth. The purpose of the review article was to summarize and discuss the available information concerning the effects of peroxide releasing bleaching agents on dental restorative materials and restorations. SOURCES: Information from all original scientific full papers or reviews listed in PubMed or ISI Web of Science (search term: bleaching AND (composite OR amalgam OR glass ionomer OR compomer OR resin OR alloy) were included in the review. DATA: Existing literature reveals that bleaching therapies may have a negative effect on physical properties, marginal integrity, enamel and dentin bond strength, and color of restorative materials as investigated in numerous in vitro studies. However, there are no reports in literature indicating that bleaching may exert a negative impact on existing restorations requiring renewal of the restorations under clinical conditions. CONCLUSION: Bleaching may exert a negative influence on restorations and restorative materials. Advice is provided based on the current literature to minimize the impact of bleaching therapies on restorative materials and restorations.

Composite Resins↗

PubMed2002

Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel.

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV-VIS-NIR spectrophotometer. Five non-carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1-day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non-uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.

Animals↗

PubMed2005

Effect of a carbamide peroxide bleaching gel containing calcium or fluoride on human enamel surface microhardness.

This in vitro study evaluated the surface microhardness of human enamel submitted to bleaching with 10% carbamide peroxide (CP) containing calcium or fluoride. Ninety-eight dental blocks (5 x 5 mm2) with polished enamel surfaces were randomly assigned to 7 treatment groups (n=14), as follows: without bleaching and storage in artificial saliva (control); 10% CP; 10% CP + 0.05% calcium; 10% CP + 0.1% calcium; 10% CP + 0.2% calcium; 10% CP + 0.2% fluoride; and 10% CP + 0.5% fluoride. During 14 days, enamel surfaces were daily exposed to a 6-h bleaching regimen followed by storage in artificial saliva. Surface microhardness was measured before (baseline), during (7th day), immediately after bleaching (14th day) and 1 week post bleaching. Data were analyzed by two-way ANOVA and Tukey's test (p<0.05). All treatments reduced SM significantly during the bleaching cycle (7th day), immediately after bleaching (14th day) and 1 week post bleaching, compared to baseline and to the unbleached control group. In conclusion, in spite of the addition of calcium and fluoride, all bleaching treatments affected the enamel surface microhardness.

Calcium↗

PubMedDate not supplied

Composite resin bond strength after enamel bleaching.

This study evaluated the effect of enamel bleaching with a commercial product on the sheer bond strength of a composite resin. A total of 45 human extracted permanent molars were used. A flat enamel surface was obtained with 600-grit SiC paper. The teeth were then randomly distributed into three groups of 15 teeth each: Group 1: Enamel etching with 37% phosphoric acid gel (Coe) for 60 seconds, placement of an unfilled resin (Coe) thinly applied with a brush and a composite resin (Occlusin); Group 2: Enamel bleaching (Rembrandt Lighten Bleaching Gel, Den-Mat) for one hour, etching for 60 seconds and placement of unfilled and composite resins. Group 3: Enamel bleaching for 24 hours, etching for 60 seconds, and placement of unfilled and composite resins. A nylon ring over the etched enamel retained the composite resin. The teeth were thermocycled (X100) and sheared with a knife-edged blade in an Instron machine running at a cross-head speed of 1 mm/min. The results in MPa were: Group 1: 12.86 +/- 4.83, Group 2: 12.33 +/- 2.95, and Group 3: 7.67 +/- 1.98. An ANOVA revealed that Groups 1 and 2 were significantly different from Group 3 (P < 0.001). Fracture within the enamel occurred in 53% in Group 1, 33% in Group 2, and 0% in Group 3. The study reveals that the shear bond strength of composite resins is significantly reduced after enamel bleaching for 24 hours.

Analysis of Variance↗

PubMed1997

Bleaching following porcelain veneers: clinical cases.

These clinical reports present two somewhat identical cases needing bleaching of the opposing teeth following placement of porcelain veneers. Using a new light-activated power bleaching gel (Opalescence Xtra) eliminated color discrepancies between veneered and non-veneered teeth. In both cases ideal esthetic results were achieved.

Adult↗

PubMed2004

[Effect of 10-15% carbamide peroxide on enamel fluoride concentration in vital bleached teeth].

The objective of the study was to evaluate the concentration of fluoride in human enamel before and after bleaching using 10-15% carbamide peroxide and after application of the fluoride varnish. Microsamples of enamel were collected using acid biopsy and the concentration of fluoride in the superficial and underlying layer was assayed. No significant differences were observed in the concentration of fluoride in both layers of enamel before and after bleaching as well as after varnish application. Bleaching with 10-15% carbamide peroxide has no influence on the concentration of fluoride in enamel.

Biopsy↗

PubMed2004

Effect of different peroxide bleaching regimens and subsequent fluoridation on the hardness of human enamel and dentin.

STATEMENT OF PROBLEM: Bleaching of teeth by "in-office" or "home" bleaching techniques are popular methods of whitening teeth. However, bleaching may reduce the surface hardness of enamel and dentin. PURPOSE: The purpose of this study was to evaluate (1) the effect of different concentrations of 2 "in-office bleaching" and 2 "home bleaching" agents applied for different time periods on the hardness of enamel and dentin and (2) the effect of subsequent immersion in a low-concentration fluoride solution on the hardness of bleached enamel and dentin. MATERIAL AND METHODS: The enamel and dentin of 12 extracted intact human molar teeth were sectioned lengthwise, ground, polished, embedded in acrylic resin and divided into 4 groups each (n=12). An area of approximately 5 x 5 mm of enamel and dentin tested for Knoop hardness number (KHN; kg/mm 2 ) at a load of 100 g for 20 seconds (baseline). The specimens were stored in distilled water for 1 hour and the microhardness testing repeated as a control group. The groups were bleached as follows: Group OX and Group OQ were bleached "in office" with Opalescence Xtra (35% hydrogen peroxide) and Opalescence Quick (35% carbamide peroxide), respectively, for 5, 15, or 35 minutes and retested for KHN at the end of each time period. "Home bleaching" products Opalescence F (15% carbamide peroxide) and Opalescence (10% carbamide peroxide) were applied in 14-hour applications at 24-hour intervals to Groups OF and O, respectively, which were then tested for KHN. Specimens were immersed in 0.05% fluoride solution (Meridol) for 5 minutes and retested for KHN. The hardness values were analyzed by 2-way ANOVA and Scheffe post hoc test (alpha=.05). Comparisons of KHN between each time and the baseline measurement for each group were of interest. RESULTS: Significant decreases in KHN of enamel and dentin were found after bleaching for all test groups, dependent on the accumulated bleaching time. Group OX showed a 25% KHN reduction for enamel and 22% for dentin after 35 minutes bleaching (P < .0001). Group OQ showed a 13% KHN reduction (P < .0001) for enamel and 10% for dentin after 35 minutes (P < .005). Group OF showed a KHN reduction of 14% for enamel (P < .05) and 9% for dentin (P < .0001) after 14 hours bleaching, and Group O showed an 18% reduction in enamel (P < .0001) and 13% in dentin (P < .0001) for the same period. Fluoridation completely restored the softened dental tissues. CONCLUSION: The "in-office" bleaching technique reduced the hardness significantly more than the "home" bleaching technique. Low-concentration fluoride mouth rinse (Meridol) restored the softened dental tissues.

Analysis of Variance↗

PubMed2000

A randomized clinical trial comparing a novel 5.3% hydrogen peroxide whitening strip to 10%, 15%, and 20% carbamide peroxide tray-based bleaching systems.

A randomized and controlled, parallel-group clinical trial compared the whitening benefits of a novel 5.3% hydrogen peroxide bleaching strip to 10%, 15%, and 20% carbamide peroxide tray-based bleaching systems. A total of 36 healthy adults were randomized to a 14-day regimen in which both arches were whitened for 1 hour per day in the whitening-strip group or 2 hours per day in the tray groups. Efficacy was measured objectively using digital images of the anterior teeth at baseline and after 14 days of treatment. Overall tooth color (L*a*b*) was derived from individual pixel values, and then mean levels of delta b*, delta L*, and composite color (delta E*) were compared using analysis of covariance. After 14 days of treatment, all groups experienced a greater than 1-unit mean improvement in delta b*, delta L*, and delta E* relative to baseline. For the primary study variable, reduction of yellow (delta b*) outcomes after 14 hours of using the experimental strip were comparable to those observed with the 10% tray group after 28 hours of use. These two treatment groups did not differ statistically with respect to any of the color measurements used in this study. For the tray groups, there was a reasonable dose relationship for the primary end point, delta b*, with the 15% and 20% tray groups averaging 17% and 68% improvements in yellow, respectively, over the 10% group. Except for the 20% carbamide peroxide system, where sensitivity was relatively common, all test products were well tolerated. In this first comparative evaluation vs marketed controls, use of the whitening strips twice daily for 14 days yielded a highly significant improvement in tooth color vs baseline.

Adult↗

PubMed1994

Intracanal isolating barriers as they relate to bleaching.

Four restorative materials were evaluated for effectiveness as intracanal isolating barriers to prevent leakage of bleaching agents into the coronal part of the root canal. Fifty-five teeth were stained in vitro, instrumented, and filled with gutta-percha. In the experimental groups, gutta-percha was removed 2 mm apical to the labial cementoenamel junction, and an intracanal isolating barrier (zinc oxide-eugenol, IRM, Ketac-Cem, or Scotchbond Multipurpose) was placed even with the facial and proximal cementoenamel junction areas in a sloped manner. All were bleached with a thermocatalytic and walking bleach technique until the crown was one shade lighter than the original shade. The roots were then examined for the occurrence of bleaching. The results indicate that none of the materials used was a totally effective intracanal isolating barrier. Although a significant difference was found when IRM was compared with Ketac-Cem or Scotchbond Multipurpose (p < 0.05), all restorative materials evaluated showed a high incidence of leakage as demonstrated by bleached roots. There was no significant difference between zinc oxide-eugenol and IRM.

Chi-Square Distribution↗

PubMedDate not supplied

Vital bleaching agents and oral antiseptic: effect on anaerobic bacteria.

This in vitro study compared the antimicrobial effect of several at-home bleaching agents and an oral antiseptic against anaerobic bacteria that are commonly found in the oral cavity. Zones of inhibition produced by Rembrandt Lighten Bleaching Gel, Opalescence, and Peroxyl were measured and compared. All the materials produced zones of inhibition with the five bacteria used in the study.

Bacteroides↗

PubMed1992

Prerestorative bleaching: effect on microleakage of Class V cavities.

The effect of bleaching extracted teeth on the microleakage of subsequently placed Class V composite resin restorations was evaluated. Ten extracted premolars were stored in water at 37 degrees C to serve as controls. Ten premolars were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. These specimens were stored in water at 37 degrees C except during treatment periods. Class V cavity preparations were then placed at the cementoenamel junction of the facial and lingual surfaces of all teeth. Half of the teeth of each group were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. After 24 hours of storage in 37 degrees C water, the teeth were thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that prerestorative bleaching did not affect the marginal seal of subsequently placed restorations.

Analysis of Variance↗

PubMed2004

Effect of carbamide peroxide bleaching agents on tensile strength of human enamel.

OBJECTIVES: The aim of this study was to evaluate the effects of low concentrations of carbamide peroxide bleaching agents (CP) on the ultimate tensile strength of enamel (UTS). METHODS: Resin composite structure was built-up on the bonded occlusal surface of 12 sound third molars to facilitate specimen preparation for microtensile testing. The bonded teeth were sectioned in a bucco-lingual direction in slices approximately 0.7 mm thick. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the 'neck' of less than 1 mm2. The sample was randomly divided into six groups of 10 specimens each: Control (C-untreated); Opalescence 10% (O10), Opalescence 15% (O15), Opalescence 20% (O20), Whiteness 10% (W10) and Whiteness 16% (W16). Specimens in each group received the application of the CP for 6 h/day, at 37 degrees C, during 14 days and were stored in artificial saliva in between each application. After the bleaching regimen, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by ANOVA and Tukey test (5%). RESULTS: Mean tensile strengths were (MPa): C = 47.5 +/- 6.2a; O10 = 37.6 +/- 5.8b; O15 = 33.2 +/- 6.0b; O20 = 31.2 +/- 3.5b; W10 = 32.5 +/- 6.1b; W16 = 30.6 +/- 7.7b. Specimens subjected to the bleaching regimen presented significantly lower UTS than the control group. No differences were found among the type and concentration of the bleaching agents. SIGNIFICANCE: Results suggested that bleaching enamel with CP could significantly reduce its UTS within a 14 days treatment.

Analysis of Variance↗