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Bleaching vital and non-vital has now become, for most dentists, a routine treatment. However the use of caustic products is not without risks. This article is a report of several publications that appeared in the endodontic literature cautioning the practitioner. Practical hints are given to reduce the side-effects for the patient.
OBJECTIVES: The objective of this study was to determine the effects of carbamide peroxide (CP) and hydrogen peroxide (HP) bleaching on the flexural strength (FS) and flexural modulus (FM) of dentin. METHODS: 2x2x20mm bovine dentin specimens were immersed in the bleaching agents to simulate overnight (10 or 15% CP, 6h daily, 2 weeks), exaggerated overnight (10% CP, 6h/day, 5 days/week, 2 months), daytime (6.5 or 7.5% HP, 1h daily, 3 weeks) and in-office (35% HP, 1h/day, 2 days/week, 3 weeks) treatment protocols. Distilled water (DW) and a placebo gel acted as control immersion materials. After immersion, the specimens were rinsed and stored in DW. Mechanical testing was performed 24h after the last treatment using an Instron Universal Testing Machine with a crosshead speed of 0.75 mm/min. The results were analyzed by ANOVA and Tukey's tests (p<0.05). RESULTS: There were significant reductions in the FS and FM of dentin after 2-week and 2-month exposures to CP. There were no significant differences in the FS or the FM of the dentin among the HP treatment and control groups. CONCLUSIONS: Direct in vitro application of CP bleaches caused significant decreases in dentin FS and FM. Similar decreases were not observed among the HP-treated dentin groups, which were exposed to shorter treatment times. Further research is needed to determine the effect of CP and HP on dentin in vivo.
Time-dependent changes in the pH value of various types of sodium perborate solutions used as bleaching agents were evaluated. Sodium perborate-monohydrate (MH), sodium perborate-trihydrate (TRH), and sodium perborate-tetrahydrate are available. Each perborate was mixed with 10%, 15%, or 30% fresh hydrogen peroxide or with bidistilled water in a powder to liquid ratio of 2 g:1 ml, respectively. The pH values were recorded at baseline and after 1h, 1 day, 3 days, and 7 days, respectively. At baseline the pH values of MH, TRH, and tetrahydrate in conjunction with 30% H2O2 were 8.7, 7.0, and 7.5, respectively. The pH increased significantly with decreasing concentrations of H2O2. For TRH, MH, and tetrahydrate mixed with bidistilled water more alkaline values were measured at baseline and after 1 h. Due to solidification of the samples, the pH could not be determined for MH starting day 1 and for TRH starting day 3. In conclusion, the pH of bleaching pastes depends on the content of water of crystallization in sodium perborate, H2O2 concentration, and time of measurement. The bulk of the mixtures recorded reached alkaline pH values of 10 to 11. It is recommended that the pH of the mixture being used be checked to avoid potential postbleaching root resorption.
This in vitro study aimed to assess dentin permeability quantitatively after the use of different irrigants into the pulp chamber, with or without ultrasonic activation, before the application of an internal bleaching agent. Thirty maxillary anterior teeth, treated endodontically, were randomly assigned to six groups, according to the irrigant used: group I, distilled water; group II, 17% EDTA; group III, 1% sodium hypochlorite; for groups IV, V, and VI, respectively, the same solutions were used, but were ultrasonicated. In groups I, II, and III, the irrigant that filled the pulp chamber was left undisturbed for 15 s and was then aspirated; in groups IV, V, and IV, the irrigants were placed into the pulp chamber, ultrasonic-activated for 15 s, and were then aspirated. This sequence was repeated three times for all groups. Afterwards, for all groups, the pulp chamber was dried, filled with a bleaching agent, and sealed with glass ionomer cement. At each change of the whitening agent, these procedures were repeated. Then, the temporary restorations were removed, access cavities were cleaned, and teeth were immersed in a 10% copper sulfate aqueous solution, submitted to vacuum and immersed in a 1% rubianic acid alcohol solution. Copper ion penetration was revealed by the rubianic acid. After staining, roots were removed at the cemento-enamel junction (CEJ) and sectioned in a mesiodistal direction starting from the cervical plug level. The sections were thinned, observed under an optical microscope, the images were digitized, and copper ion penetration was measured in each section using a specific software. Means and SD were: group I, 2.41 (+/-1.45); group II, 5.22 (+/-1.79); group III, 8.32 (+/-2.55); group IV, 3.73 (+/-0.89); group V, 14.83 (+/-4.99); and group VI, 10.51 (+/-2.65). Statistical analysis using two-way anova and Tukey test showed that, regardless of the irrigant, ultrasonication increased dentinal permeability (P < 0.01). Comparing the overall effectiveness of the tested solutions, EDTA yielded the greatest increase in dentinal permeability (P < 0.01). Based on these results, it may be concluded that use of ultrasonic-activated irrigants in the pulp chamber, before the accomplishment of internal dental bleaching procedures, may result in a remarkable increase of dentin permeability, which may enhance the efficiency of the whitening agent.
PURPOSE: This study determined hydrogen peroxide release into the oral cavity during use of different home bleaching products and compared them with accepted safe levels. METHODS: Determination of peroxide in saliva was performed with peroxidase, phenol and 4-aminoantipyrin in a photometric method. Upper jaw incisors were bleached with individual trays charged with 350 mg Opalescence 10%, Opalescence 15% (OP) and Vivastyle (V). Additionally, Whitestrips (WS) designed for upper or lower jaw were used. All systems were adopted by five subjects for 30 minutes on different days. Whole saliva was collected at 2-minute intervals during the first 10 minutes of bleaching and every 5 minutes thereafter. RESULTS: Highest release of peroxide was found for all products in the saliva sample collected initially after application of the bleaching agent. Total amount of peroxide released into saliva during 30-minute bleaching period was 0.78+/-0.45 for Opalescence 10% and 1.52+/-0.44 mg for Opalescence 15%. Significantly more peroxide was released from Vivastyle (2.67+/-1.03 mg) and from Whitestrips (upper: 3.25+/-5,65, lower: 2.09+/-0.34 mg). A significantly smaller fraction of the charged peroxides was released into saliva from individual trays than from Whitestrips during the 30-minute use time. From the peroxide loaded in the trays or strips the following fractions were released during the application period: Opalescence 10% (6.4+/-3.7%), Opalescence 15% (8+/-2.4%), Vivastyle (18.6+/-8.5%), upper Whitestrips (30.4+/-4.9), lower Whitestrips (27.4+/-4.4%). In terms of amount/kg body weight the bleaching systems led to a single exposure of 0.013-0.056 mg/kg which is distinctly less than the maximum safe daily dose of 0.26 mg/kg/day if calculated for a small person (58 kg/128 lbs).
The surface modifications and the coefficient of thermal expansion of compomers after treatment with a 30% hydrogen peroxide bleaching agent were investigated. Three compomers (Compoglass F, Elan and F2000) were nonbleached and bleached for 1 and 3 days. The surface modification and the coefficient of thermal expansion of each bleached compomer were evaluated using a scanning electron microscope and a thermomechanical analyzer, respectively. As a result, Compoglass F and Elan showed slight surface degradation, whereas F2000 showed many cracks on its surface and these cracks were not observed in Compoglass F and Elan. Bleached Elan and F2000 has changed to the extent where their the coefficient of thermal expansion increased compared with those of nonbleached specimens. In addition, bleached compomers showed a strong inverse correlation between the coefficient of thermal expansion and the volume percent of filler.
Standardized cylinders of light-cured composite resin were bonded to the ground labial enamel surface of bovine incisor teeth that had been immersed in double-distilled water for 7 days after having been (a) immersed in hydrogen peroxide for 5, 30, or 60 min, then etched for 60 s with 37% phosphoric acid; (b) immersed in saline for 5, 30, or 60 min, then etched for 60 s with 37% phosphoric acid; (c) etched with 37% phosphoric acid for 60 s, then immersed in hydrogen peroxide for 5, 30, or 60 min; or (d) etched with 37% phosphoric acid for 60 s, then immersed in saline for 5, 30, or 60 min. The enamel surface was washed with water for 1 min and dried with compressed air for 30 s prior to applying the resin. The tooth and applied resin were stored in water at 37 degrees C for 1 day prior to shear and tensile testing. A total of 192 specimens was used, 8 for each enamel preparation mode, for each time period, and for each test. Test values were tabulated and statistically analyzed. Analysis of variance revealed significantly higher bond strength values (p less than 0.005) for hydrogen peroxide-treated as compared with saline-treated specimens. A significant interaction was also noted between test solution and etching order. Scanning electron microscopic examination of failed shear- and tensile-tested specimens revealed no significant solution-related differences in the fracture pattern or the resin quality.(ABSTRACT TRUNCATED AT 250 WORDS)
INTRODUCTION: This study assessed the effect of a 35% hydrogen peroxide bleaching gel on the shear bond strength and bond failure site of a resin-modified glass ionomer (Fuji Ortho LC, GC Europe, Leuven, Belgium). METHODS: Forty-five bovine mandibular permanent incisors were randomly divided into 3 groups; each group contained 15 teeth. Bleaching treatment was performed at 2 different times before the bonding procedure. Forty-five stainless steel brackets were bonded with the resin-modified glass ionomer. After bonding, all samples were stored in distilled water for 24 hours and then tested in shear mode on a testing machine. RESULTS: Group 1 (no bleaching) showed significantly higher shear bond strength values than groups 2 (bleaching immediately before bonding) and 3 (bleaching 1 week before bonding). No significant differences were found between groups 2 and 3. Moreover, no significant differences in debond locations were found among the 3 groups. CONCLUSIONS: Bleaching treatment before bonding significantly lowered the bond strength values of Fuji Ortho LC.
Vital bleaching of teeth is, increasingly, a popular esthetic desire. Bleaching agents are provided in over-the-counter as well as dental office bleaching kits. However, the effect of the bleaching agents on the enamel surface is not fully understood, and cautions approaches to their use are not usually explained to patients. In this study, an in vivo exposure of bleaching agents is used to evaluate the short and long-term effect on the enamel surface; the results are demonstrated by scanning with an electron microscope. Exposure to the bleaching agents for 14 days created an alteration of the enamel surface and caused exposure of the enamel prisms. Moreover, a 21- to 90-day post-exposure SEM evaluation demonstrated alteration of the surface enamel, indicating exposure of the enamel prismatic layer, frequently to the depth of the enamel rods and possibly the dentin.
Hydrogen peroxide and heat are two components of a technique commonly used to bleach human teeth. The effects of these two components on pulp tissue of dog teeth were evaluated histologically. Hydrogen peroxide alone or with heat caused obliteration of odontoblasts, hemorrhage, resorption, and inflammatory infiltration, while heat alone was not detrimental. Pulpal changes demonstrated evidence of reversibility after 60 d.
PURPOSE: To test the effect of three carbamide peroxide bleaching products, Opalescence (O), Nite White (N), and Platinum (P) on mercury release from amalgam (Valiant PhD). MATERIALS AND METHODS: Sixty uniform amalgam specimens were prepared in Acrylite clear acrylic blocks. After aging for 1 week at 37 degrees C, the specimens were placed in individual polystyrene jars containing 20 mL of sterile saline, and divided into three groups A, B, and C. Specimens were bleached in cycles by removing them from the jars, blotting to remove excess moisture, and covering with either O, N, P, or saline control (SC). After 8 hours, the specimens were cleaned with a toothbrush, rinsed with deionized water, and returned to the saline. Group A was tested for mercury release after 8 hours of bleaching, Group B after 40 total hours of bleaching, and Group C after 80 total hours of bleaching. Mercury testing was performed by first reducing the mercury in solution in each jar with 1 mL of SnCl2, and then testing the remaining headspace with a Gold Film Mercury Vapor Analyzer. RESULTS: ANOVA indicated there was no significant difference between the bleaches and controls at 8 and 40 hours, however at 80 hours, O caused significantly more mercury release (P < 0.05). Means at 80 hours in mg/m3 were: O = 0.98 +/- 0.36; N = 0.58 +/- 0.20; P = 0.47 +/- 0.11; SC = 0.52 +/- 0.14.
Recent improvements in the in-office techniques for bleaching teeth have reduced chair time, simplified the procedure and reduced the potential for pulpal inflammation and other side effects. Home bleaching has become very popular, but many patients will still prefer the faster, in-office procedure done by their dentist. This comparison of two 35 percent hydrogen peroxide products confirms that these procedures are effective and should be a part of any practice providing esthetic improvements for its patients.
This study evaluated the influence of 3 different photopolymerization sources on enamel shear bond strength after bleaching with 10% carbamide peroxide. Seventy-two incisive bovine teeth were randomly divided into 6 groups (n=12) according to bleaching treatment and photopolymerization source used: G1 -- Bleached / Halogen lamp; G2 -- Not bleached / Halogen lamp (control); G3 -- Bleached / Light-emitting diodes (LED); G4 -- Not bleached / Light-emitting diodes (LED) (control); G5 -- Bleached / Xenon plasma arc; G6 -- Not bleached / Xenon plasma arc (control). Experimental groups were exposed to bleaching agent for a period of 14 days, with a daily contact of 4 h and then stored in artificial saliva at 37 degrees C. Control groups were stored in artificial saliva at 37 degrees C for same period of bleaching treatment. Procedures for bonding composite resin to enamel were carried out according to manufacturer instructions. After storage in distilled water at 37 degrees C for 24 hours, all samples were submitted to shear bond strength test. G2 had the highest mean value (14.86 MPa) while G5 had the lowest (12.32 MPa). The comparison of groups by 2-way ANOVA showed that there were no significant differences for either of the factors considered in this study (bleaching and photopolymerization source), hence the interaction between these factors. It was therefore possible to conclude that neither enamel bleaching nor the photopolymerization source used had any influence on enamel shear bond strength.
Research concerning bleaching agents on the mechanical properties of composite resin restorative materials has produced conflicting reports. Representative brands of composite resin restorative materials were studied, including microfil, hybrid, and posterior types. The bleaching agents selected were 30% hydrogen peroxide and two commercial brands of 10% carbamide peroxide. Ten specimens of each material, prepared according to American National Standards Institute/American Dental Association specification No. 27 for diametral tensile testing, were stored in bleaching agents for 1 hour and 168 hours at 37 degrees C. An equal number of specimens stored in deionized water with identical conditions were designated controls. Qualitative examination of bleached specimens revealed a marked change in color, especially the microfilled composite resins. There was no significant difference in tensile strength between controls and exposed samples at either time except for the diminished strength of microfilled composite resins in 30% hydrogen peroxide for one week (p < 0.01).
OBJECTIVE: The esthetic application of bleaching materials has gained popularity, with consequences for teeth and restorative materials. The aim of this investigation was to evaluate the influence of different bleaching agents with varying peroxide concentrations on restorative materials. METHOD AND MATERIALS: The color behavior, Vickers hardness, and surface roughness were determined on different restorative materials and bovine enamel. Cylindric samples of two fine hybrid composites, one microfilled composite, one compomer, and one ormocer were bleached for two 2-hour periods with three commercial and three experimental bleaching agents with varying peroxide concentrations. The properties were determined before and after bleaching. As a control, all materials were investigated without bleaching after a 14-day storage. RESULTS: The restorative materials showed maximum changes in Vickers hardness of 44, maximum changes in surface roughness of between 0.2 and 0.7 microm, and a maximum discoloration of deltaE = 6.8. A statistically significant deterioration of hardness, combined with the highest discoloration, was found for the microfilled composite and the compomer. Different bleaching systems showed varying effects on surface roughness. CONCLUSION: Bleaching resulted in a deterioration of the restorative materials, indicated by a decrease of hardness and an increase in surface roughness. Generally, bovine enamel showed significantly higher discoloration compared to the restorative materials.
Bleaching offers a non-interventive way of improving the appearance of sound, yet discolored anterior teeth. Until recently, the whitening agent was applied using a tray, but now other methods of delivering whitening agents, such as those using brush applicators, are available. This study investigated the tooth whitening efficacy of two novel, self-applied tooth whitening systems containing either 18% (Group 1) or 16.4% (Group 2) carbamide peroxide. Ninety-five subjects, ranging in age from 18 to 70 with anterior teeth A3 or darker, were recruited and randomly allocated to a group. The subjects were instructed to apply the formulation to all maxillary anterior teeth after brushing in the morning and evening. At baseline, two weeks and six months the upper six anterior teeth of the subjects were measured using the Vita shade guide tab system. In addition, the gingival health of the labial surfaces of the upper six anterior teeth was assessed using the Loee and Silness Gingival index (Loee & Silness, 1963) at baseline and at two weeks. The mean (SD) reduction in shade guide scores was 4.1 (2.4) shade guide tabs for subjects in Group 1, compared to 3.7 (2.6) shades for those in Group 2. This difference was not statistically significant (p=0.5). During the course of study, the gingivitis scores reduced from a mean (SD) of 0.91 (0.62) at baseline to 0.44 (0.55) at final examination (48% reduction). At the six-month recall, the mean (SD) reduction in shade guide scores was 2.3 (2.7) shade guide tabs for subjects in Group 1, compared to 2.5 (2.5) shades for those in Group 2. The different concentrations tested were found to be equally effective in improving the whiteness of upper anterior teeth by approximately four shades over a two-week period and the majority of the whitening benefit (c.60%) was sustained at six-month recall.
Aim of the study was to determine peroxides in saliva, released during bleaching procedures. Upper incisors of five subjects were bleached with Whitestrips (5% H2O2) and Vivastyle (10% carbamide peroxide, tray charged with 225mg) for 30min, each on different days. Saliva was collected before and during the whole period of bleaching at different intervals. The amount of peroxide in the salivary samples was assessed with peroxidase, phenol and 4-aminoantipyrin in a photometric assay. Additionally the amount of peroxides in the bleaching material was determined before and after the bleaching, so that the peroxide release into saliva could be balanced. The amount of peroxides released into saliva was related to the bleaching system and only partially influenced by the individual salivary flow rate. Bleaching with Vivastyle led to lower release of peroxides into saliva compared to Whitestrips (Vivastyle: 0.8+/-0.17mg; Whitestrips: 1.5+/-0.84mg). Salivary flow rate was not correlated to release of peroxides from the bleaching products. It can be concluded that the enzymatic method adopting 4-aminoantipyrin and peroxidase is valid for the determination of peroxides in saliva. Furthermore distinctly more peroxides are released into the oral cavity from Whitestrips than from trays charged with Vivastyle .
Bleaching materials containing hydrogen peroxide have been used for treating discolored nonvital teeth but their use was occasionally associated with external root resorption. In a previous study it was found that the immediate results of bleaching teeth in vitro were equal for sodium perborate mixed with either water or hydrogen peroxide. The purpose of this study was to compare the bleaching prognosis of sodium perborate mixed with water or hydrogen peroxide over a 1-yr period. Extracted human teeth with intact crowns were discolored with human erythrocytes and bleached by sodium perborate mixed with either 30% hydrogen peroxide (group A), 3% hydrogen peroxide (group B), or water (group C). The bleaching materials were placed in the pulp chambers of the discolored teeth and sealed with IRM. They were replaced with fresh preparations after 3 and 7 days. After 14 days the coronal access cavities were sealed with composite resin and the teeth photographed with a color slide film under standardized conditions. The teeth were stored in artificial saliva for 1 yr and photographed after 3, 6, and 12 months. Two separate evaluators ranked the teeth by comparing them with the shades before and after bleaching. The bleaching success rates of the tested groups at each time interval were compared and analyzed statistically. It was found that after 1 yr all of the teeth in groups A and C maintained their shades. In 20% of the teeth in group B there was color regression. Statistically, these differences were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)