Microhardness Of Bovine Enamel Research Articles

EVALUATION OF PH LEVELS AND THE EFFECT OF VIOLET LED LIGHT IN-OFFICE BLEACHING PROTOCOL ALONE OR ASSOCIATED WITH 6% H2O2 ON ENAMEL MICROHARDNESS

This in vitro study evaluated the effect of three different in-office bleaching techniques on bovine enamel microhardness and the pH variation of peroxide agents during the protocols. Methodology: For Knoop microhardness (KNH) analyses, enamel fragments were divided into 3 groups (n=10): LEDv–hybrid violet LED/Laser light (10x2’ LEDv + 10x30” light-off, 2 cycles); HP6%LEDv–6% HP gel + LEDv/Laser (15x1’ LEDv + 15x1’ light-off); HP35%- 35% HP (1x45’). For pH measurements, bovine teeth were divided into 2 groups (n=10): HP35% and HP6%LEDv. KHN was measured at baseline (T0), 24h after bleaching (T1) and after 7 days in artificial saliva (T7). Initial and final bleaching gels pHs were obtained utilizing a pH-meter. KHN was evaluated by the Wald-type permutation statistic, aligned rank transformation statistical test, Wilcoxon and Mann-Whitney tests; pH levels were evaluated by the Welch-James and Wilcoxon tests (p<0.05). Results: HP35% and HP6%LEDv presented a decrease in KHN from T0 to T1, with no difference among them; baselines values were recovered at T7. For LEDv, no significant difference was found between KHN at T1 and T0; at T7 KHN increased in comparison to T0. The initial pH mean was 7.66 for HP35% and 9.28 for HP6%LEDv; the final pH mean was 7.53 and 8.68, respectively. Conclusions: Bleaching with LEDv alone was the only treatment that didn’t reduce enamel microhardness. HP6%LEDv led to a decrease in KHN values similar to the high-concentrated gel. After seven days in artificial saliva, initial KHN was recovered. Although the pH of both gels decreased during the treatment, it remained above the critical value.

Influence of Bleaching Agent Containing Bioactive Glass on Color and Microhardness of Bovine Enamel

Influence of Bleaching Agent Containing Bioactive Glass on Color and Microhardness of Bovine Enamel

Effect of Actilux - Activated Whitening Toothpaste and Marine Salts on Color Change and Microhardness of Bovine Enamel

Purpose: To evaluate the effect of Actilux-activated whitening toothpaste and Marine salts powder on color change and microhardness of bovine enamel. Methods: Thirty intact bovine incisors were used in this study to produce enamel specimens. The specimens were randomly distributed into three groups (n= 10) according to the tested whitening agents as follows: Group I: BW; BlanX LED White Shock (Actilux-activated), Group II: MS; Marine salts whitening powder and Group III: CR; Crest regular fluoridated toothpaste. The specimens were stained using black tea solution for 5 days. Each specimen was brushed twice daily for 8 then 15 days. The color was assessed according to CIE (Lab) color system using a VITA Easyshade spectrophotometer. The microhardness was assessed using Digital Display Vickers Microhardness Tester at baseline, after staining, after 8 days, and 15 days brushing. Data were tabulated and statistically analyzed. Results: After 8 days brushing, BW showed the highest mean (ΔE) while MS and CR both showed lower mean (ΔE). BW and MS showed the highest mean (ΔE) after 15 days brushing with no statistically significant difference between them. After 15 days; BW showed the highest mean microhardness followed by MS while CR showed the lowest mean microhardness. Conclusion: Both Actilux-activated toothpaste combined with LED device and Marine salts powder were effective in tooth whitening as well as increasing enamel microhardness. The whitening efficacy and microhardness is time dependent.

Microhardness of bovine enamel after different fluoride application protocols.

The aim of the present study was to evaluate microhardness, mineral recovery and the enamel surface after the application of topical fluoride to artificial dental caries. Twenty-five bovine enamel blocks were prepared for artificial caries-like lesions and randomly divided into five groups (n=5): untreated (C control), 1.23% acidulated phosphate fluoride gel (APG), 2% neutral fluoride gel (NFG), 1.23% acidulated fluoride mousse (AFM) and fluoride varnish (5% Duraphat, DFV). Knoop microhardness (KHN) was evaluated after 7 and 14 days of treatment as well as 1 week after 28 days of treatment. Electron and confocal microscopy and energy dispersive spectroscopy were performed. KHN data were treated with two-way ANOVA (material×time) and Tukey's test at a 5% significance level. Differences were found among groups over time (p<0.001). Microhardness varied after 7 and 14 days of treatment and remained stable 1 week after 28 days of treatment. Mineral recovery and enamel topography varied among groups, with the fluoride varnish achieving the most uniform topography.

Harmful Effect of Beer on Bovine Enamel Microhardness - In Vitro Study.

This study aimed to evaluate the effect of beers on the bovine enamel microhardness. Fifty rectangular (1 x 3 x 1 mm–height x width x thickness) enamel specimens were obtained from permanent bovine incisors, and divided into five groups (n = 10) according to the treatment employed: Saliva, Coke, Brahma, Heineken, and Budweiser. Microhardness (Knoop) were obtained before; after 5, 30 and 60 min of immersion in each solution. The data were analyzed using repeated two-way ANOVA and Tukey´s test (p<0.05). Coke decreased the microhardness in all immersion times, and Heineken, showed low values after 60 minutes. Beers tested have low potential to cause enamel erosion when compared to Coke.

Do different bleaching protocols affect the enamel microhardness?

Objective:Tooth bleaching tends to increase enamel roughness and porosity, in addition to reducing surface microhardness. The aim of this in vitro study was to evaluate the effects of bleaching treatments using different hydrogen peroxide (HP) concentrations, with and without light activation on bovine enamel microhardness.Materials and Methods:The buccal surfaces of sixty bovine incisors were flattened and polished and the enamel specimens were divided into six groups: G1 : c0 ontrol, exposed to artificial saliva; G2: 35% HP applied in two sessions (45’ each); G3: 35% HP applied in two sessions (3 × 15’ each); G4: 35% HP applied in one session (3 × 7’30”) plus hybrid light (HL); G5: 25% HP applied in one session (3 × 7’30”) plus HL; and G6: 15% HP applied in one session (3 × 7’30”) plus HL. After the treatment, the enamel specimens were stored in artificial saliva. The surface microhardness (Knoop) was measured at the baseline, 24 h and 7 days after bleaching. The data was analyzed using the ANOVA test, followed by the Tukey–Krummer test (P < 0.05).Results:All bleaching procedures lead to a decrease in surface microhardness when compared with the control group after 24 h. The lowest change in surface microhardness was found in the specimens treated with 15% HP plus HL. However, 35% HP plus HL induced the highest decrease in surface microhardness. After 7 days of remineralization, the surface microhardness returned to normal levels for all bleached specimens.Conclusion:Therefore, it can be concluded that the bleaching protocols caused a slight enamel surface alteration. However, the remineralization process minimized these effects.

Cross-sectional microhardness of bovine enamel subjected to three paediatric liquid oral medicines: an in vitro study

This study aimed to investigate the in vitro effects of three paediatric liquid oral medicines on bovine dental enamel subsurfaces under pH cycling conditions. Bovine enamel blocks were evaluated for surface hardness at baseline for sample selection. 52 intact bovine enamel blocks (16mm(2)) were randomly divided into four groups (n=13) according to the immersion treatments: G1: antibiotic (Klaricid®), G2: antihistamine (Claritin®), G3: antihistamine (Dimetapp®) and G4: control (de-ionised water). The blocks were submitted to pH cycling treatments twice a day for 12 days. The medicines were evaluated for pH, viscosity, and concentration of calcium, phosphate and fluoride. After the treatment period, cross-sectional microhardness (CSMH) measurements of the enamel blocks were taken and the data, expressed in Knoop hardness number (kg/mm(2)) was used to calculate the ΔS. ANOVA followed by the Tukey test were used for statistical analyses (p<0.05). The antibiotic Klaricid® showed the highest concentration of fluoride, calcium and phosphate. Considering pH and viscosity, the following pattern was observed according to the treatment group: G4>G1>G2>G3 and G1>G2>G3>G4 respectively. Regarding the demineralisation pattern, the following results were observed: G4>G3>G2>G1. Compared to the control, the antibiotic and both the antihistamines provoked less demineralisation of the enamel blocks (p<0.05). Antibiotic G1 (Klaricid®) presented an in vitro protective effect against acid attacks probably due to its mineral content and viscosity.

In vitro evaluation of the microhardness of bovine enamel exposed to acid solutions after bleaching

Acid erosion is a superficial loss of enamel caused by chemical processes that do not involve bacteria. Intrinsic and extrinsic factors, such as the presence of acid substances in the oral cavity, may cause a pH reduction, thus potentially increasing acid erosion. The aim of this study was to evaluate the microhardness of bleached and unbleached bovine enamel after immersion in a soda beverage, artificial powder juice and hydrochloric acid. The results obtained for the variables of exposure time, acid solution and substrate condition (bleached or unbleached enamel) were statistically analyzed by the ANOVA and Tukey tests. It was concluded that a decrease in microhardness renders dental structures more susceptible to erosion and mineral loss, and that teeth left unbleached show higher values of microhardness compared to bleached teeth.

Effect of fluoride-containing bleaching agents on bovine enamel microhardness

Aim: The purpose of this study was to evaluate the effect of 10% carbamide peroxide (10%CP) bleaching agents with different fluoride concentrations on enamel microhardness after induction of artificial caries lesions during pH-cycling model. Methods: Bovine dental enamel blocks with known surface microhardness were subjected to caries lesion induction and another surface microhardness was determined after a demineralization protocol. The enamel blocks were divided into four groups (n=17) and subjected to 12-day pH-cycling. The groups consisted of the following treatments: 1) artificial saliva (control group not subjected to bleaching treatment); 2) 10%CP; 3) 10%CP (with 0.11% fluoride); 4) 10%CP (with 0.5% fluoride). After treatments, the enamel was evaluated using surface microhardness, polarized light microscopy (PLM) and scanning electronic microscopy. The percentage of surface microhardness recovery was determined for each group and analyzed by the Kruskal Wallis and Dunn’s tests (a=0.05). The values of lesion depth by PLM were analyzed by ANOVA and Tukey’s test (a=0.05). Results: The enamel treated with bleaching gels containing or not fluoride presented lower mineral recovery and higher caries lesion depth than the control group. Conclusions: These data suggest that bleaching procedures on enamel with artificially induced caries lesions should be used with caution even in the presence of fluoride because there was no recovery in the microhardness.

Effectiveness of home bleaching agents in discolored teeth and influence on enamel microhardness

Objectives:This study evaluated the effectiveness of different home bleaching agents on color alteration and their influence on surface and subsurface microhardness of discolored bovine enamel.Material and Methods:Forty-five fragments of bovine incisors were randomly allocated into 3 groups (n=15) according to the bleaching agent: 10% carbamide peroxide gel (CP10), 16% carbamide peroxide gel (CP16) and 6.5%-hydrogen-peroxide-based strip (HP6.5). Before bleaching treatment, initial values of Knoop surface microhardness and color (CIEL*a*b*) were obtained and the fragments were artificially stained in hemolyzed rat blood. Then, bleaching treatments were performed over a 21-day period. Color changes (ΔE) were assessed at 7, 14 and 21 days, and final surface microhardness reading was done after 21 days. Thereafter, the fragments were bisected to obtain subsurface microhardness. Data were subjected to ANOVA and Tukey's tests (α=5%).Results:Color changes produced by CP16 were similar to those of CP10, and the color changes produced by these materials were significantly superior to those produced by HP6.5. Color changes at 21 days were superior to 7 days and similar to 14 days. The time did not influence color changes for CP16, which showed similarity between the 14- and 21-day results. No statistically significant differences were found among the home bleaching agents for surface and subsurface microhardness.Conclusions:Microhardness of bovine enamel was not affected by the bleaching agents. The 16% carbamide peroxide gel was the most effective for bleaching the stained substrate.

Effect of fluoride containing bleaching agents on enamel surface properties

Objectives To evaluate the effects of fluoridated bleaching agents and post-bleaching fluoridation treatment on the whitening efficiency and microhardness of bovine enamel. Methods Twenty five freshly extracted bovine incisors were cut into halves, embedded and then divided into the following five groups: Group 1, untreated controls; Group 2, treatment with 10% carbamide peroxide (CP) bleaching agent; Group 3, treatment with 10% CP followed by a 0.9% sodium fluoride gel application, Group 4, treatment with 10% CP containing 0.11% fluoride; Group 5, treatment with an experimental bleaching agent consisting of 10% CP and 0.37% fluoride. Groups 2–5 were treated 8 h per day for 14 days then immersed in saliva for 2 weeks. Enamel morphology changes were evaluated under SEM on Day 14. Changes in enamel color and microhardness were evaluated on Days 7 and 14, and compared with the baseline data. Additionally, microhardness was determined on post-bleaching Days 21 and 28. Results After 2 weeks, an erosion pattern was noted on the specimens in Groups 2 and 3. Groups 4 and 5 showed a milder demineralized pattern. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 3 showed significantly decreased enamel microhardness compared to their baseline data. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. Conclusions The fluoridated bleaching agents produced less demineralization of surface morphology and microhardness. The addition of fluoride did not impede the whitening effect.