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PubMed2004

In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing.

The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra) values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.

Analysis of Variance↗

PubMed2004

Safety and efficacy of a nightguard bleaching agent containing sodium fluoride and potassium nitrate.

OBJECTIVES: Transient sensitivity during bleaching is generally reported to affect 67% of patients. While most people tolerate this sensitivity, some find it impossible to continue treatment. The purpose of this study was to determine the safety and efficacy of an experimental, low-sensitivity bleaching agent. METHOD AND MATERIALS: Twenty-two participants bleached for a minimum of 6 hours per night over a 2-week period. The bleaching agent used, Experimental Product E, is a 10% carbamide peroxide gel containing potassium nitrate and sodium fluoride. Evaluations were performed at baseline and 1,2,13, and 26 weeks. Color change was measured using a value-ordered Vita classic shade guide and a colorimeter. Sensitivity of the teeth, gingiva, tongue, and/or throat was measured daily using a patient log. RESULTS: The median color change after 2 weeks was eight tabs. Approximately 36% reported sensitivity during the active whitening phase of the study. As a group, participants reported sensitivity during 13.7% of the total days spent whitening. CONCLUSION: Experimental Product E was shown to be safe. Participants experienced minor sensitivity during the active bleaching phase only. Experimental Product E was shown to be an effective bleaching agent for the subjects tested in this study.

Adult↗

PubMed1992

Improved esthetics with a combined bleaching technique: a case report.

This paper describes a clinical case in which a combination bleaching technique was used to improve the appearance of the patient's discolored anterior teeth. Enamel microabrasion was used first to remove superficial fluorosis stains. A home bleaching regimen was then used to lighten the overall shade of the teeth, which had appeared more yellow after microabrasion.

Adolescent↗

PubMed1999

Effect of carbamide peroxide bleaching on the shear bond strength of composite to dental bonding agent enhanced enamel.

STATEMENT OF PROBLEM: Carbamide peroxide bleaching has been implicated in adversely affecting the bond strength of composite to enamel. PURPOSE: This in vitro study evaluated the effect of 3 dental bonding agents (OptiBond, All-Bond 2, One-Step) on the shear bond strength of a hybrid composite to enamel which was treated by a 10% carbamide peroxide bleaching system. MATERIAL AND METHODS: Cylinders of composite were bonded to carbamide peroxide-treated enamel on extracted human teeth using 3 dental bonding agents. After thermocycling, shear bond strengths were determined with a universal testing machine. RESULTS: OptiBond aided bond strengths were 23.7 +/- 5.6 MPa to bleached and 19.6 +/- 2.9 MPa to unbleached enamel. For All-Bond 2, bleached enamel exhibited bond strengths of 14.9 +/- 4.0 MPa and unbleached enamel exhibited a bond strength value of 20. 4 +/- 2.3 MPa. The composite bond strength for One-Step was 13.6 +/- 5.9 MPa to bleached and 23.0 +/- 3.9 MPa to unbleached enamel. There was no statistical difference between OptiBond (alcohol base) aided bond strengths for bleached and unbleached enamel; however, the bond strength of composite to bleached enamel with All-Bond 2 or One-Step (acetone base) was significantly lower than unbleached controls. CONCLUSION: The effect of bonding agent usage on composite bond strength to enamel bleached with a particular carbamide peroxide was dependent on the bonding agent used.

Analysis of Variance↗

PubMed2000

A direct approach to restore anterior teeth.

When selecting the correct treatment for a patient with anterior esthetic problems, the dentist must choose between direct and indirect procedures. With situations allowing conservative treatment, direct resin restoration should be given strong consideration. Advances in materials and techniques that can positively affect this choice include pre-restorative bleaching procedures, new bonding agents, and new highly esthetic direct resin systems. A procedure is described to maximize esthetics and minimize finishing time during direct resin placement.

Color↗

PubMed2003

Effect of bleaching on fracture toughness of composite-dentin bonds.

PURPOSE: The effect of carbamide peroxide concentration and length of exposure on fracture toughness (KIC) of existing composite-dentin interfaces was assessed using the notchless triangular prism (NTP) specimen KIC test. MATERIALS AND METHODS: Freshly extracted human molars and premolars were wet ground on 600-grit SiC to obtain 4 x 4 x 4 x 4 mm triangular prisms, exposing buccal or lingual dentin. Dentin surfaces were bonded using a resin composite (Z-250, 3M) and SingleBond dentin bonding system (3M) to obtain 180 8-mm-long dentin-composite NTP specimens. The bonding system was applied using the "wet-bonding" technique. The bonded specimens were randomly assigned to 20 groups. The effect of exposure to three control solutions (tap water, Carbopol, and Carbopol-urea) and to four concentrations (11%, 13%, 16%, 21%) of carbamide peroxide (Perfecta, Premier) was assessed. Testing was conducted after 1, 2, and 3 weeks representing a cumulative exposure of 14, 42, and 70 h. The maximum force recorded before fracture was used to calculate KIC. The data were statistically analysed using two-factor ANOVA followed by one-way ANOVA and Bonferroni multiple means comparisons. Selected fractured surfaces were characterized using SEM. RESULTS: Data analysis revealed that cumulative exposure to bleaching agent for 70 h significantly (p < 0.01) decreased the interfacial KIC, regardless of concentration. For the 16% and 21% concentrations, a significant reduction was observed after 42 h. CONCLUSION: The results suggest that bleaching could adversely affect the interfacial fracture toughness of dentin-resin composite adhesive interfaces.

Acrylic Resins↗

PubMed2002

The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

Aluminum Silicates↗

PubMed2002

In vitro analysis of effect of heat used in dental bleaching on human dental enamel.

From a cosmetic point-of-view, white teeth are important for integration of an individual into society. Thus, dental bleaching may be used to reach this objective. When analyzing several proposed techniques, it was observed that heat is frequently involved either in direct application or as a result of a chemical reaction. Taking into account the importance of preserving dental structures, the present study analyzed possible injuries to enamel when heat is used in the bleaching procedure. A colorimetric method was used and the results showed that there was no difference when heat was used. In only one case did the non-communicating tufts become communicating.

Adult↗

PubMed2002

Greening of the tooth-amalgam interface during extended 10% carbamide peroxide bleaching of tetracycline-stained teeth: a case report.

UNLABELLED: At-home bleaching with 10% carbamide peroxide in a custom-fitted tray has been shown to have some minor effects on certain brands of amalgam, pertaining to mercury release, but generally, effects on amalgam are not considered clinically significant. However, in this case report, a greening of the tooth structure in certain areas immediately adjacent to amalgam restorations in the maxillary and mandibular first molars occurred during tooth whitening. Other amalgam restorations in mandibular and maxillary second molars in the same mouth did not demonstrate any green discoloration of the teeth. Upon removal of the affected amalgam restorations, recurrent decay was present in the areas of tooth greening but not in other areas adjacent to the restoration. The teeth were restored with posterior composite restorations. Whether the green discoloration was a result of some loss of material from a particular brand of amalgam, indicating leakage, or indicative of original or recurrent tooth decay is unclear in this single-patient situation. Other patients in the same study did not demonstrate this occurrence. Dentists should be ready to replace amalgam restorations should this green discoloration in adjacent tooth structure occur during bleaching, in case decay is present. CLINICAL SIGNIFICANCE: The unusual discoloration cited suggests that amalgam restorations in potentially esthetic areas, including the lingual of anterior teeth, should be replaced prior to bleaching, to avoid the problem of difficult stain removal or translucency allowing restoration visibility following bleaching.

Adult↗

PubMed2005

Tensile bond strength of brackets after antioxidant treatment on bleached teeth.

Various studies have reported a significant reduction in tensile bond strength of brackets when bonding is carried out immediately after bleaching. The purpose of this investigation was to determine the effect of an antioxidant agent on the tensile bond strength values of metal brackets bonded with composite resin to human enamel after bleaching with carbamide peroxide (CP). A total of 80 extracted premolar teeth were randomly divided into three bleaching groups of 10 per cent CP and an unbleached control group. The specimens in group 1 were bonded immediately after bleaching; group 2 were stored in an artificial saliva solution for 7 days after bleaching; group 3 were treated with 10 per cent sodium ascorbate, immediately before bonding, whereas the unbleached specimens in group 4 had no treatment before bonding. Tensile bond strengths were established in MPa. To evaluate the amount of resin left on the enamel surfaces after debonding, the adhesive remnant index (ARI) scores were used. The tensile bond strength data were analyzed with the Kruskal-Wallis test and pairwise comparisons were made by the Mann-Whitney U test at a significance level of P < 0.05. The brackets bonded immediately after bleaching revealed significantly lower tensile bond strengths than those of unbleached enamel (P = 0.000). No statistically significant differences in tensile bond strength were noted when the delayed-bonding (P = 6.000) and antioxidant-treated (P = 0.2757) groups were compared with the control group. The antioxidant treatment immediately after bleaching was effective in reversing the tensile bond strength of brackets.

Antioxidants↗

PubMed2002

Higher-concentration carbamide peroxide effects on surface roughness of composites.

BACKGROUND: Ten percent carbamide peroxide has been used extensively within the dental profession for the purpose of bleaching teeth. Although this method has been successful, the use of higher-concentration carbamide peroxides (20-35%) for home bleaching has increased substantially in the past few years. The purpose of this study was to evaluate changes in surface roughness of a hybrid and a microfilled composite after exposure to bleaching agents containing higher concentrations of carbamide peroxide. MATERIALS AND METHODS: Sixty-eight circular, resin-based composite specimens (8 mm x 2 mm) were prepared against a Mylar surface. Half of the specimens were fabricated from a hybrid composite material and the other half with a microfilled composite. Specimens were polished with aluminum oxide finishing disks, divided into four groups, and then exposed either to 20% carbamide peroxide for 3 hours per day for 14 days or to 35% carbamide peroxide for 1 hour per day for 14 days. The mean surface roughness (Ra) was determined for each specimen before and after exposure to bleaching agents, using mechanical profilometry. Data were analyzed by two-way analysis of variance (ANOVA) for differences between composite type, carbamide peroxide concentrations, and interaction of the two factors with respect to average surface roughness. All data analysis was performed at alpha = 0.05. RESULTS: Mean change from baseline of surface roughness (Ra) of microfilled composite and 20% carbamide peroxide was -0.03 microm +/- 0.10 microm; microfilled composite and 35% carbamide peroxide: 0.01 microm x 0.02 microm; hybrid composite and 20% carbamide peroxide: -0.43 microm x 0.91 microm; hybrid composite and 35% carbamide peroxide: -0.19 microm x 0.43 microm. Surface roughness of hybrid or microfilled composite did not change significantly from baseline with either concentration of carbamide peroxide (p = .300). CLINICAL SIGNIFICANCE: Higher-concentration carbamide peroxide bleaching agents, used as intended by the manufacturer, pose no significant risk to resin composite restoration surfaces.

Aluminum Oxide↗

PubMed2003

Alterations in human enamel surface morphology following the use of an office bleaching agent and consecutive application of 37% phosphoric acid in vivo.

OBJECTIVE: The aim of this in vivo study was to evaluate the effects of a visible light-activated in-office bleaching agent, Opalescence Xtra (35% hydrogen peroxide) on the external enamel surface of human teeth by using scanning electron microscopy (SEM). METHODS: The labial surfaces of nine upper incisors from nine different patients were divided into four parts, and a bleaching agent was applied to the mesial halves of the teeth. Three weeks following this treatment, the teeth were extracted and divided into four quadrants. Each quadrant was treated with a different procedure and the samples were examined under SEM. The SEM photographs were blindly evaluated by a jury of four experts. RESULTS: Although there were no statistical differences in the rating of surface morphology of bleached and control groups, the 37% phosphoric acid etched and acid etched + bleached enamel samples demonstrated a statistically significant dissimilar surface morphology (p < 0.05). CONCLUSION: The bleached + etched enamel treatment showed an uneven etched surface compared to the acid etched control.

Acid Etching, Dental↗

PubMed2006

Surface microhardness of enamel after different home bleaching procedures.

OBJECTIVES: The purpose of this study was to evaluate the influence of different home bleaching procedures on surface microhardness of human enamel. METHODS: Among eight groups 192 incisors were distributed. The facial surface of each incisor was polished and baseline hardness of enamel (m0; Knoop) was assessed with a load of 1N for 30s. Subsequently, the enamel was treated for 14 days with the bleaching agent: groups 1, 2 and 4 Viva Style Paint on, 8% carbamide peroxide (CP) 1x20min, 2x20min and 2x5min; group 3 Colgate Simply White, 5.9% hydrogen peroxide (HP), 2x30min; group 5 Viva Style 10% CP 1x1h; group 6 Blend-a-med White Strips, 5.9% HP 2x30min; group 7 Odol-med3 Beauty-Kur, sodium chlorite 2x10min; group 8 control, running water 1x1h. Hardness was reassessed after the last bleaching treatment (m1) and after 6 weeks storage in artificial saliva (m2). RESULTS: Changes in microhardness were as follows (m0-m1): (1) -2.3 (+/-20.3); (2) -8.9 (+/-27.2); (3) 63.4 (+/-56.3); (4) 9.6 (+/-30.1); (5) 12.8 (+/-62.6); (6) 92.2 (+/-50.2); (7) 158.4 (+/-59.7); (8) 10.6 (+/-38.5). Statistical analysis showed that hardness values were significantly (p< or =0.0005; Wilcoxon test) reduced in groups 3, 6, and 7 (m1) and in group 7 (m2). SIGNIFICANCE: Both type of bleaching agent and concentration have a significant influence on the microhardness of enamel. The most critical bleaching agent seems to be the one containing sodium chlorite in combination with citric acid.

Carbamide Peroxide↗

PubMed2006

Effect of 10% carbamide peroxide dental bleaching on microhardness of filled and unfilled sealant materials.

PURPOSE: The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials. METHODS: Fluroshield, Vitroseal Alfa, and one unfilled (Clinpro) sealants were placed in Teflon matrices (4 mm in diameter by 2 mm in height) and polymerized for 40 seconds. A total of 20 specimens were prepared for each material, in which half were assigned as the control group (stored in artificial saliva and no bleaching treatment). For the remaining half, Clarigel Gold bleaching agent (10% carbamide peroxide) was placed over the specimen surface for 4 hours/day during 4 weeks. When specimens were not under bleaching treatment, they were kept in artificial saliva. Afterwards, specimens were subjected to Knoop microhardness testing using a 25-g load for 5 seconds. Five measurements were made on the sealants' surfaces and then calculated in Knoop hardness values. The data were statistically analyzed by two-way analysis of variance and Tukey's tests with a 5% confidence level. RESULTS: The results of this in vitro study showed that the application of a carbamide peroxide-based bleaching material significantly affected the microhardness values of filled sealant materials. The bleaching agent did not affect the microhardness of the unfilled sealant. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that the bleaching agents altered the surface hardness of filled sealant restorative materials. This could possibly lead to increased wear and surface roughness.

Carbamide Peroxide↗

PubMed2002

[Effectiveness of various whitening techniques and their effects on the enamel surface].

The objective of this in vitro study was to compare three different bleaching techniques with respect to the bleaching times required to achieve six grades of whitening in human teeth, i.e. from shade A4 to A3 of the VITAPAN classical shade guide. Additionally, the enamel surfaces were analyzed by SEM after each bleaching procedure to detect potential surface changes. A total of 24 anterior teeth extracted for periodontal reasons (baseline shade A4) were randomized to three different bleaching treatments (n=8): Group A Illuminé home (home-bleaching technique); group B Whitestrips (over-the-counter technique); and group C Opalescence Xtra (in-office technique). The bleaching cycles were carried out according to the manufacturers' instructions, with one bleaching cycle taking eight hours for product A, 30 minutes for product B, and 15 minutes for product C. The mean treatment time required to achieve a defined shade (A3) was 6.88 cycles (=3300 minutes) in group A, 36.25 cycles (=1087 minutes) in group B, and 4.25 cycles (63.75 minutes) in group C. None of the teeth studied showed detectable surface changes in the subsequent SEM (2000 X) analysis of the enamel surface. In this in vitro study all three techniques studied resulted in the desired tooth whitening within the recommended application time periods, and none of the three products tested created any detectable enamel surface changes.

Analysis of Variance↗

PubMed1990

Preliminary surface analysis of etched, bleached, and normal bovine enamel.

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

Acid Etching, Dental↗

PubMedDate not supplied

Effect of pre- and postoperative bleaching on marginal leakage of amalgam and composite restorations.

OBJECTIVES: The aim of this study was to investigate the effect of pre- and postoperative bleaching with 10% carbamide peroxide on marginal leakage of amalgam and resin composite restorations. METHOD AND MATERIALS: Three groups were made using 30 extracted, caries-free third molars (n = 10). In the preoperative group, bleaching was performed with 10% carbamide peroxide, followed by the placement of resin composite and amalgam restorations on Class V cavity preparations. In the postoperative group, bleaching was performed after the resin composite and amalgam restorations were fabricated. The third group served as a control in which no bleaching was performed. Dye penetration was used for evaluation of marginal leakage. RESULTS: Chi-square test showed that marginal leakage of resin composite restorations increased in both pre- and postoperatively bleached groups, but marginal leakage of amalgam restorations showed no alterations. CONCLUSION: Bleaching with carbamide peroxide may alter the marginal leakage of resin composite restorations, but amalgam restorations are not affected adversely in vitro.

Carbamide Peroxide↗

PubMed1994

Techniques for aesthetic enhancement of porcelain laminate veneer restorations: a case report.

The article is a clinical report of various techniques to enhance the aesthetic outcome of porcelain veneer restorations. Color and contour evaluation, increase in shade value, bleaching, and the use of temporary veneer restorations are presented and discussed. A case is used to illustrate the procedures. The learning objective of this article is to expand and update the knowledge of variations in current porcelain veneer restoration techniques.

Adult↗