The bleaching depth of a 35% hydrogen peroxide based in-office product: a study in vitro
ABSTRACT The aim of the present study was to quantify the penetration of 35% hydrogen peroxide into enamel and dentine and to relate this to the resultant shade change of the tooth.
The crowns of 24 caries and developmental defect free human maxillary incisors were stained internally with a standardised tea solution. Twelve specimens were power bleached with light activated 35% hydrogen peroxide and 12 placed in water; both exposure times were 30min. Three different shade assessment methods (Vita shade guide [SG], shade vision system [SVS] and a chromometer) were employed prior to, after tea staining and after power bleaching/water treatments. Twelve specimens each from the bleach group and the water control water group were sectioned mesio-distally. An additional 12 specimens from the bleach and the control group were sectioned labio-palatally. The stain area for each specimen was measured using image analysis software.
With tea staining, the mean changes in Vita shade guide units (SGU) ranged from 3.66 to 8.33. With the SVS system changes of 3.66-9 units were seen. Chromometer readings showed that following bleaching the L* values moved in the direction of black (3.8-6.7) and a* and b* values were in the red (0.3) and yellow (1.5) direction, respectively. Samples bleached and sectioned mesio-distally showed stain coverage of 28.6-39.4%, while palatal sections showed stain coverage of 58-72%. Control samples, whether sectioned mesio-distally or labio-palatally, showed staining throughout the dentine (97-100% coverage).
A 35% hydrogen peroxide in-office bleaching gel demonstrated bleaching into dentine of uniform depth.
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ABSTRACT: SUMMARY In-office bleaching is a popular treatment in modern esthetic dentistry. However, bleaching agents sometimes accidentally adhere to the gingiva and peripheral tissues, even when applied by well-trained dentists. This can lead to transient pain and whitish changes in the gingiva. Although these symptoms disappear within several hours, the effects of bleaching agents on gingiva have not been well described in the literature. The present study aimed to elucidate the cytotoxic effects of a bleaching agent on cultured human gingival fibroblasts (HGFs). We performed a comprehensive analysis of the toxic effects of in-office bleaching agents on gingiva using cultured HGFs and DNA microarray. Survival rates of HGFs decreased with increases in the concentration of hydrogen peroxide, which became significant at concentrations of 1.5 × 10(-3)% or higher at every time point. Concentrations lower than 1.5 × 10(-3)% did not affect survival rates of HGFs. Cytotoxicity of hydrogen peroxide was significantly weakened by the addition of vitamin E. Stimulation by in-office bleaching agents triggered the proinflammatory cytokine tumor necrosis factor (TNF)-α cascade in gingival fibroblasts. As the TNF-α cascade can be inhibited by vitamin E additives, treatment with vitamin E may protect gingival fibroblasts against the toxic effects of an in-office bleaching agent. The present results suggest that local administration of vitamin E to gingiva before in-office bleaching may be useful for preventing gingival irritation due to accidental adhesion of a bleaching agent.Operative Dentistry 01/2015; DOI:10.2341/14-059-L · 1.27 Impact Factor
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ABSTRACT: The purpose of this in vitro study is to assess whether the elemental content of tooth enamel is altered when bleaching the teeth with bleaching gel. Because of tooth bleaching growing popularity and to match the public demands, manufacturers increased the range of bleaching products available, changing its presentation, techniques and concentration of active principles. This way, two different bleaching products were compared, one for in-office and another for domestic use. In order to perform this evaluation, sound vestibular surfaces of anterior healthy teeth, extracted for periodontal or orthodontic reasons, were treated with the bleaching products accordingly to manufacturer instructions.Spectra were acquired using the M4 Tornado μ-XRF setup, and quantitative calculations were performed using fundamental parameter method to determine the elemental composition of the analyzed samples before and after treatment.No significant statistical differences in the mineral content of the analyzed teeth were obtained. Copyright © 2014 John Wiley & Sons, Ltd.X-Ray Spectrometry 01/2015; 44(1). DOI:10.1002/xrs.2569 · 1.19 Impact Factor
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ABSTRACT: OBJECTIVE: The aim of this study was to determine the effect of different hydrogen peroxide concentrations (HP) on mercury and other metal ions release from admixed and spherical dental amalgam. MATERIALS AND METHODS: Dental amalgam discs were prepared from GS.80 and Lojic+ alloys (Southern Dental Industries, Australia) according to manufacturer's instructions in stainless steel moulds (10mm diameter and 2mm thickness). The discs (n=25 of each alloy) were divided into five equal groups for each alloy. Each group was immersed in 20 ml of 38%, 24%, 10%, or 3% HP solution for 24 h at 37 o C with 0% (distilled water) as control. Following immersion procedure, solutions were taken for metal ion release determination (Hg, Ag, Sn and Cu) using inductively coupled plasma mass spectrometry (ICP-MS). Statistical analysis was conducted using one and two way ANOVA tests to determine significance of differences between test groups. Bonferroni Post Hoc test was conducted for multiple comparisons. RESULTS: Metal ion release for the elements (Hg, Ag, Sn and Cu) increased with exposure to increasing concentrations of HP for both GS.80 and Lojic+ amalgam alloys. The differences in concentration of metal ions released after treatment with 0% (control), 3%, 10%, 24% or 38% HP were statistically significant (p < 0.05). CONCLUSION: Metal ions (Hg, Ag, Cu and Sn) were released from dental amalgam following treatment with all HP concentrations. Metal ion release increased with increasing HP concentration. Even with exposure of dental amalgam to relatively high HP concentration (38%), released Hg did not exceed the maximum acceptable limit.