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At least 793 records · Page 44Linked to original sources
PubMed2006

Effect of bleaching agents on the microhardness of tooth-colored restorative materials.

STATEMENT OF PROBLEM: There is no consensus concerning the effect of bleaching gels on microhardness of restorative materials. Information about the effect of whitening strips on microhardness of restorative materials is also limited. PURPOSE: The purpose of this study was to evaluate the effect of a bleaching gel and a whitening strip on the microhardness of 3 tooth-colored restorative materials. MATERIAL AND METHODS: Forty cylindrical specimens (6 x 2 mm) of each restorative material, including a nanohybrid composite resin (Grandio), a polyacid-modified composite resin (Dyract eXtra), and a glass-ionomer cement (Ionofil Molar AC), were prepared and stored in distilled water at 37 degrees C for 24 hours. The specimens were then polished using medium, fine, and superfine polishing disks and stored in 37 degrees C distilled water for 7 days. Specimens were divided into 4 groups (n=10). One group was selected for baseline Vickers hardness measurements (load 100 g, dwell time 20 seconds) of the top surfaces. The other 3 groups were treated for 21 days with 1 of the following: distilled water (control), bleaching gel (10% carbamide peroxide), or whitening strip (14% hydrogen peroxide). The top surfaces of the treated specimens were also subjected to the same hardness testing performed for the baseline specimens. Data were analyzed with 2-way analysis of variance and Tukey Honestly Significant Difference tests (alpha=.05). RESULTS: There were no significant differences in microhardness between the test groups of each restorative material. However, significant differences in microhardness were observed among restorative materials. For all test groups, composite resin showed the highest hardness values, whereas glass-ionomer cement presented the lowest (P<.05). CONCLUSION: The bleaching products used in this study did not adversely affect the microhardness of the restorative materials.

Acrylic Resins↗
PubMedDate not supplied

At-home bleaching system: effects on enamel and cementum.

An analysis by scanning electron microscopy was undertaken to investigate the effects of bleaching on enamel-cementum surface morphology. Teeth were investigated in five groups: control; vital bleached for 5, 15, and 30 days; and 37 percent phosphoric acid gel etched for 20 seconds. Only the gel-etched group exhibited etching patterns. Shade change in vital bleached teeth was noted in the group vital bleached for 30 days.

Dental Cementum↗
PubMed2005

The clinical performance of professionally dispensed bleaching gel with added amorphous calcium phosphate.

BACKGROUND: The authors undertook a study to measure how the addition of amorphous calcium phosphate (ACP) to a professionally dispensed 16 percent carbamide peroxide equivalent bleaching gel affects tooth color and dentinal hypersensitivity. METHODS: The authors assigned two groups to use either the test gel containing ACP or a control gel. Both groups used their respective products for three hours daily for 14 days. At checkpoints during the treatment period, the authors studied tooth color, gingival health and three measures of hypersensitivity. They performed double-blinded clinical measurements on days three, seven, 14 and on the fifth day post-treatment. RESULTS: The test group demonstrated significantly lower (P < .05) mean thermal sensitivity scores compared with baseline (day 14: 0.21 versus 0.31; fifth posttreatment day: 0.06 versus 0.18). Tactile sensitivity also was substantially lower (P < .05) for test subjects (day 14: 0.26 versus 0.48; fifth posttreatment day: 0.06 versus 0.19). Furthermore, at the conclusion of the study, twice as many subjects were free of thermal sensitivity (test group, 80 percent, compared with control group, 40 percent; P < .001) and there was a similar significant (P < .001) percentage difference for tactile sensitivity. Both groups demonstrated equivalent and significant tooth color enhancement as compared with baseline (control: -7.73 shade change versus test: -8.12; P < .05). CONCLUSIONS: This study demonstrates that ACP could be added to a 16 percent carbamide peroxide equivalent bleaching gel and result in a significant reduction of clinical measures of dentinal hypersensitivity, both during and after treatment. CLINICAL IMPLICATIONS: The results of this study offer evidence in support of clinical decisions to treat patients with bleaching gel containing ACP when uncompromised tooth whitening efficacy is desired, yet dentinal hypersensitivity may be a concern.

Adult↗
PubMed1992

Leaching of hydrogen peroxide from bleached bovine enamel.

Accurately weighed bovine enamel slabs were individually immersed in 2 ml of 35% hydrogen peroxide for 1, 3, 5, 30, or 60 min. A control group was obtained by individual immersion of bovine enamel slabs in 2 ml of saline for 60 min. All samples were washed, dried, acid-etched with 37% phosphoric acid for 60 s, then washed and dried again. Two milliliters of double-distilled water were used for individual sample leaching. Leaching was done for 1, 5, 10, 20 min, or 7 days for the experimental groups and for 7 days for the control group. The samples of one of the experimental groups were leached for a second time for 1 min. A total of 112 samples was used in this study. Hydrogen peroxide was spectrophotometrically identified and quantified in all leaching solutions based on the oxidation reaction of leuco-crystal violet buffer solution by hydrogen peroxide, a reaction catalyzed by horseradish peroxidase. The results revealed a significant difference in the quantity of leached peroxide between bleached samples (irrespective of the duration of leaching) and control, saline-treated ones. No difference was observed in the quantity of leached peroxide between releached samples and control, saline-treated ones. However, these were small, random, and numerically insignificant. Statistically significant differences were also noted among some of the experimental groups. They were thought to hold no clinical significance. The results suggested that upon immersion, the complete leaching of peroxide from bleached enamel occurs rapidly.

Animals↗
PubMed1991

An new concept for removal of dental fluorosis stains.

Bleaching has been suggested by several authors in order to treat the unaesthetic aspect of dental fluorosis. Many results are, however, unsatisfactory. A different method, based on the structural characteristics of the fluorotic tooth and the organic and exogenous nature of fluorotic enamel stains, includes three principal stages: 1--enamel etching with 12% HCl in order to eliminate the posteruptive calcified layer that covers the fluorotic enamel surface and to denude the microcavities containing the organic elements; 2--application of pure manufactured sodium hypochlorite to remove these organic stains; and 3--filling the chemically opened microcavities with a light-cured dental adhesive to provide the tooth with a smooth and even surface and to prevent restaining. To improve the aesthetic aspect of intensely discolored teeth, it is possible to use a variety of tints available in several composite resin kits. Teeth with a rough enamel surface react more positively than ones with a smooth surface. The enamel adhesives provide better results than the amelo-dentinal ones.

Acid Etching, Dental↗
PubMed2000

Mercury release from dental amalgam after treatment with 10% carbamide peroxide in vitro.

OBJECTIVES: The effect of 10% carbamide peroxide on mercury release from dental amalgams was assessed in vitro by using a cold-vapor atomic absorption Mercury Analyzer System. STUDY DESIGN: Samples of 4 commercial brands of dental amalgam, Megaloy (Dentsply/Caulk, Milford, Del), Mega+ (CFPM, Aulnaye, France), Nongama 2 (Silmet, Or Yehuda, Israel), and Valiant Ph.D. (Dentsply/Caulk, Milford, Del), were treated for 48 hours with 10% carbamide peroxide and compared with samples treated with phosphate buffer. RESULTS: Amalgam specimens exposed for 48 hours to 10% carbamide peroxide showed significantly higher concentrations of mercury in solution as compared with specimens treated with phosphate buffer (P <.001). Megaloy and Valiant Ph.D. yielded significantly higher mercury concentrations in solution than Mega+ and Nongama 2 (P <.001). Mega+ yielded significantly higher mercury concentrations in solution than Nongama 2 (P <.05). No significant differences were found in mercury concentrations in solution between Megaloy and Valiant Ph.D. CONCLUSIONS: Treatment with 10% carbamide peroxide bleaching agents caused an increase in mercury release from amalgam restorations, possibly increasing exposure of patients to its adverse effects. Amalgam brands differed in the amounts of mercury release after bleaching with carbamide peroxide.

Carbamide Peroxide↗
PubMed2000

Penetration of the pulp chamber by bleaching agents in teeth restored with various restorative materials.

It is thought that externally applied bleaching agents may penetrate into the pulp chamber. This study was conducted to evaluate the diffusion of peroxide bleaching agents into the pulp chamber of teeth restored with various restorative materials. Sixty-five human extracted anterior maxillary teeth were separated into the 13 groups containing 5 teeth. Five teeth (control group) were not subjected to any cavity preparation and restoration. Standardized class V cavities were prepared in the other 60 teeth and restored using composite resin (Charisma), polyacid modified composite resin (Dyract), or resin-modified glass ionomer cement (Vitremer). All teeth were sectioned 3 mm apical to the cementoenamel junction to remove the intracoronal pulp tissue, and the pulp chamber was filled with acetate buffer to absorb and stabilize any peroxide that might penetrate. Vestibular crown surfaces of teeth in the experimental groups were subjected to four different bleaching agents for 30 min at 37 degrees C, whereas the teeth in the control groups were exposed only to distilled water. Then the acetate buffer solution in the pulp chamber of each tooth was removed, and the pulp chamber of each tooth was rinsed with 100 ml of distilled water twice. Leukocrystal violet and enzyme horseradish peroxidase were added to the mixture of the acetate buffer and rinse water. The optical density of the resulting blue solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. Higher hydrogen peroxide concentrations resulted in a higher pulpal peroxide penetration. The highest pulpal peroxide penetration was found in resin-modified glass ionomer cement groups, whereas composite resin groups showed the lowest pulpal peroxide penetration.

Acetates↗
PubMed1995

Effects of home bleaching on the tissues of the oral cavity.

Eight subjects used a 10 per cent carbamide peroxide (Opalesence) home bleaching system in a mouthguard for 14 nights. Their periodontal health was assessed by measuring gingival crevicular fluid flow with a Periotron 6000, and subjects were given a questionnaire to assess the effects of the bleaching system. There was no significant change in the gingival crevicular fluid flow, recession, bleeding index or plaque index of any patient during the treatment phase. All treated teeth were lightened, and mild transient tooth sensitivity was common to all participants. One subject experienced internal tooth discoloration, possibly due to marginal leakage around an amalgam restoration.

Adult↗
PubMed1990

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.

Acid Etching, Dental↗
PubMed1998

Anterior fixed prosthetic restorations and the bleached dentition: laboratory techniques.

The process of matching fixed prosthetic restorations to bleached dentition has often created a dilemma, as clinicians are not able to accurately communicate shade selection to the dental laboratory. By understanding the effect of vital bleaching on the dentition, it is possible to fabricate porcelain restorations that match the bleached natural teeth. This article presents a laboratory technique for utilizing a sequence of porcelain powders and stains to develop the internal anatomy (e.g., halos, mamelons, luminosity) of restorations that appear indistinguishable from the bleached dentition.

Adult↗
PubMed2006

Recovery of peroxides in saliva during home bleaching--influence of smoking.

UNLABELLED: The study aimed at determining hydrogen peroxide recovery in saliva during use of different home bleaching products by smokers and non-smokers. Peroxide recovery was evaluated with respect to the safe level reported in the literature. Determination of peroxide levels in saliva was performed with peroxidase, phenol and 4-aminoantipyrin in a photometric method. Four different bleaching regimens were used by 10 smokers and 10 non-smokers: Whitestrips, Vivastyle (tray-based) and two paint-on products (Crest Night Effects, Colgate Simply White). Whole saliva was collected and total amount of peroxide (mg) released during the 60 min bleaching period was determined: Colgate Simply White: 2.67 +/-0.88 (non-smokers); 2.66 +/- 1.17 (smokers); Crest Night Effects: 0.23 +/- 0.13 (non-smokers); 0.25 +/-0.16 (smokers); Vivastyle: 2.47 +/- 0.82 (non-smokers), 2.44 +/- 1.31 (smokers); Whitestrips: 1.39 +/- 0.62 (non-smokers), 2.02 +/- 1.86 (smokers). In terms of amount of peroxide kg(-1) body weight the bleaching systems led to a single exposure of 0.004-0.046 mg kg(-1), which is distinctly less than safe daily dose of 0.26 mg kg(-1) day(-1), if calculated for a small person (58 kg). The criterion smoker versus non-smokers had no influence on peroxide levels in the oral cavity. CONCLUSION: Smoking did not appear to impact the anti-oxidant defence capacity of the oral cavity with respect to degrading peroxides released from bleaching products. Significantly lower amounts of peroxides were detected in saliva during application of the paint-on product Crest Nights Effects compared with the other bleaching systems.

Carbonates↗