10%过氧化脲漂白无髓牙的临床研究

目的 :评价 10 %过氧化脲对变色无髓牙的漂白效果。方法 :对 8例患者的 8颗变色无髓牙 ,制作含储药池的扇形个别托盘 ,并开放舌侧髓室口 ,去除根充牙胶至釉牙骨质界下 2～ 3mm ,然后用玻璃离子覆盖 2～ 3mm。治疗中 ,患者临睡前将 10 %过氧化脲注入髓室及个别托盘的储药池内 ,从而同时从内外两侧对无髓牙进行漂白。患者晨起后 ,清洁牙齿 ,用无菌棉球充填髓室。治疗结束后 ,暂时充填髓腔 ,两周后改行光固化充填。结果 :8颗变色无髓牙在 3周内均获得满意效果。无髓牙漂白所用时间与着色时间成正比。结论 :10 %过氧化脲能有效地治疗变色无髓牙。     

A clinical assessment of the effects of 10% carbamide peroxide gel on human pulp tissue.

Bleaching vital teeth with 10% carbamide peroxide gel is a routine procedure in which there has been no evidence of associated permanent pulpal damage. Synthesis of the enzyme heme oxygenase-1 (HO-1) is increased after exposure of eukaryotic cells to conditions of oxidative stress (including H2O2) as a defense against the damaging effects of free radicals. Dental pulps were evaluated for HO-1 (aka Heat Shock Protein 32) presence in teeth treated with 10% carbamide peroxide. Seventeen intact first premolars scheduled for orthodontic extraction were bleached for 4 h immediately preceding extraction. Fourteen additional premolars from the same individuals were not bleached. All 31 teeth were extracted, fixed, demineralized, frozen, sectioned, and immunostained with anti-HO-1 antibody using a standard ABC protocol. There was no significant difference in the presence of HO-1 between total bleached versus total unbleached teeth using the Fisher's Exact Test (p < or = 0.05). However, the histological findings could be interpreted to suggest that coronal odontoblasts and endothelial cells in the underlying pulp proper may have the potential to respond to oxidative stress by increasing the synthesis of HO-1 (HSP32). This could represent a component of an initial defensive response by specific cells in strategic locations in the pulp that precedes classical inflammatory pathways.     

Bleaching primary teeth with 10% carbamide peroxide.

Bleaching teeth with 10% carbamide peroxide in a custom-fitted tray has been popular for more than 10 years. However, primary teeth are seldom considered for bleaching due to the need for compliance by the child and the natural whiteness of the primary teeth. This report describes an indication-teeth darkened from trauma-as well as the technique and outcome for bleaching discolored primary teeth.     

The effect of a 10% carbamide peroxide home bleaching system on the gingival health

Esthetics plays an important role in dentistry today. Because of an increased emphasis on beauty and health, cosmetic dentistry has been the thrust to the forefront of many practices. Many health products are used for bleaching teeth, but all side effects are not known. Tooth sensitivity and gingival irritation are the most common side effects, but they are typically mild and transient in nature. The aim of this investigation was to evaluate objectively the effect of 10% carbamide peroxide gel (Opalescence Utradent Inc, USA) on gingival health by measuring changes in Bleeding Index, Plaque Index, and Gingival Index. Eighteen subjects, 11 female and 7 male, age range 15-30 years (mean 24 years), were selected for the study as a convenient sample. Their teeth had either fluorosis, dental stains, smoking, or tetracycline staining. The Opalescence system was used as office monitored, at-home bleaching for three weeks. There was a statistically significant reduction in bleeding on probing (1% - 37%, p < or = 0.003), Plaque Index (4% - 50%, p < or = 0.000), and Gingival Index (2.5% - 34%, p < or = 0.002). Only two subjects reported tooth hypersensitivity, and none of the subjects complained about gingival irritation. There was a positive change in tooth color as far as staining was concerned. Further research including randomized controlled, double blind clinical trials is needed to confirm these findings and to examine other factors related to bleaching of teeth.     

The efficiency of 10% carbamide peroxide gel on dental enamel

This study investigated the effect of 10% carbamide peroxide gel on human tooth color, vibrational mode, and mineral loss. The exposed enamels were bleached for two weeks (six hours' bleaching and 18 hours' storage in distilled water per day). Color change was calculated from the CIE L*a*b* color values. Vibrational mode in Fourier transform Raman spectrum and mineral content were also estimated. The bleached enamels showed an apparent color change (deltaE* = 5.35). Within the test period, their whiteness increased linearly as the period increased. A slight decrease in Raman peak at 1068 cm(-1)--compared with the peak at 430 cm(-1)--was observed after bleaching. The total mineral content was decreased from 90.39 to 86.01 after bleaching. Also, the calculated Ca/P ratio decreased from 2.10 to 2.07. However, these changes were negligibly different from the enamels stored in distilled water except for a color change.     

Clinical trial of three 10% carbamide peroxide bleaching products

BACKGROUND: A profusion of commercial bleaching systems exists on the market today, but there are few clinical comparisons of these systems. METHODS: In this study, three different commercial 10% carbamide peroxide bleaching systems were used by 24 patients in an overnight protocol for two weeks. Each patient used two of the bleaching products simultaneously in a side-by-side comparison. RESULTS: The mean onset of tooth whitening was 2.4 +/- 1.7 days. Tooth sensitivity was the most frequent side effect, as 64% of the patients reported tooth sensitivity occurring after 4.8 +/- 4.1 days and lasting for 5.0 +/- 3.8 days. Although intrapatient differences were recorded for the three commercial 10% carbamide peroxide bleaching systems by the patients, there were no statistical differences in the time of onset of subjective tooth whitening and the onset, frequency and duration of tooth sensitivity among the three commercial bleaching systems when compared pairwise or independently (p < 0.05). CONCLUSION: Selection of which bleaching product to use should be based on the concentration of the active ingredient, the viscosity of the product and other marketing features. Further research is needed to investigate the causes of tooth sensitivity and methods to reduce its severity and frequency.     

Microcomputerised tomography evaluation of 10% carbamide peroxide applied to enamel

OBJECTIVES: There is still some controversy in the dental literature whether carbamide peroxide bleaching causes demineralization of teeth. One of the reasons for this controversy is that there is as yet no reliable, non-destructive in vitro method for assessing mineral loss in bleached teeth. The objective of this study was to investigate the possible demineralization effect of 10% carbamide peroxide bleaching agent on enamel and dentine non-destructively. METHODS: microCT images were obtained of 12 human molar tooth sections. These sections had 10% carbamide peroxide applied for eight hours a day over a period of 15 days. Further tomographic images were obtained and the mineral content prior to and post bleaching assessed. RESULTS: A total of 144 regions were evaluated using the image processing language available in the work station. The application of 10% carbamide peroxide was found to cause demineralization of the enamel extended to a depth of 50 microm below the enamel surface (Paired t-test, p<0.05). CONCLUSIONS: This study confirmed that microCT was indeed a highly suitable method for assessing mineral content of dental enamel after bleach application. It is recommended that application of bleaching agents should be carefully considered in patients susceptible to caries and tooth wear.     

Effects of 10% carbamide peroxide on the enamel surface morphology: a scanning electron microscopy study

Background: Several studies have been published about the effect of carbamide peroxide on enamel surface morphology. However, only a few studies have been carried out under intraoral conditions. The purpose of this study was to investigate the effect of two commercially available 10% carbamide peroxide bleaching products (Colgate Platinum and Starbrite) on the enamel surface morphology under intraoral conditions.
Materials and Methods: Twenty-four subjects were divided into two groups and assigned a product to use for 2 weeks. Epoxy resin replicas obtained from the maxillary right central incisors of the subjects before, immediately after, and 3 months after the bleaching procedure were examined under a scanning electron microscope.
Results: Immediately after the bleaching procedure, the surface porosity of enamel had increased in the Colgate Platinum group, whereas erosive surface alterations were observed in the Starbrite group. At 3 months, the surface morphology of enamel in the Colgate Platinum group was similar to the untreated enamel surface. In the Starbrite group, erosive defects on the enamel surface had decreased within 3 months, and the appearance of the enamel surface was almost the same as the untreated enamel.
Conclusion: Even though both bleaching agents caused alterations in the surface morphology of enamel, these alterations were reversed within 3 months following treatment.
CLINICAL SIGNIFICANCE
The results of this study suggest that 10% carbamide peroxide bleaching products cause alterations in enamel surface morphology immediately after bleaching, and the degree of these alterations depends on the brand of bleaching agent and duration of application time. However, these alterations revert to almost normal within 3 months.     

In situ effect of 10% carbamide peroxide on microhardness of human enamel: function of time

Purpose: This study evaluated the effect of two home bleaching regimens (1 h/day versus 7 h/day for a total of 21 days) on the microhardness of superficial enamel treated with 10% carbamide peroxide gel.
Materials and Methods: Rectangular enamel specimens (2.5 × 2.5 × 1 mm) were obtained from human third molars and mounted on the palatal aspect of removable orthodontic retainers. Nine enamel specimens were mounted in each of 10 retainers, used by 10 volunteers during the active phase of the study. Modified 0.089 cm thick bleaching trays were fabricated for each participant. Each bleaching tray fit a participant's arch and the retainer containing the enamel specimens. Enamel specimens were treated with a 10% carbamide peroxide bleaching gel (Nite White® Excel 2Z, Discus Dental, Culver City, CA, USA) for either 1 h/day ( n = 30) or 7 h/day ( n = 30), both for 21 days. Three enamel specimens in each retainer were never treated and served as controls. The retainers were worn by the participants whether or not they underwent bleaching. This simulated the natural action of the saliva/oral fluids on the enamel specimens. Enamel specimens were subjected to pre- and post-treatment microhardness measurements. Post-treatment Knoop hardness numbers were compared with baseline values and analyzed statistically.
Results: Bleaching treatment resulted in a nonsignificant reduction in microhardness values when compared with values of the control nontreated specimens (1.7% and 2.5% reduction in hardness for 1 h/day and 7 h/day, respectively). There was no difference in microhardness between the different treatment regimens.
Conclusion: Home bleaching with 10% carbamide peroxide for up to 7 h/day for 21 days does not significantly affect enamel microhardness.
CLINICAL SIGNIFICANCE
Bleaching with 10% carbamide peroxide for 1 h/day or 7 h/day for a total of 21 days is safe for human enamel.     

The influence of chemical activation on tooth bleaching using 10% carbamide peroxide

The aim of this study was to assess the influence of manganese gluconate, a chemical activator of bleaching agents, at a concentration of 0.01% on the efficiency of a 10% carbamide peroxide-based bleaching agent. Forty bovine incisors were immersed in a 25% instant coffee solution for seven days and randomly divided into two groups. Group 1 was the control group and consisted of 10% carbamide peroxide-based bleaching gel only. Group 2 consisted of 10% carbamide peroxide-based bleaching gel and 0.01% manganese gluconate. Three readings of color were taken using the Vita Easyshade spectrophotometer: the initial reading, a reading at seven days, and a reading at 14 days. Total color variation was calculated by ΔE*Lab. Data were submitted to the statistical t-test (5%), which showed that after seven days group 2 had a significant increase in the degree of tooth bleaching compared with group 1. The mean values (±SD) were 16.33 (±3.95) for group 1 and 19.29 (±4.97) for group 2. However, the results for group 1 and group 2 were similar after 14 days. Adding 0.01% manganese gluconate to 10% carbamide peroxide bleaching gel increased the degree of tooth bleaching after a seven-day treatment and did not influence the resulting shade after 14 days.     

A clinical evaluation of 10 percent vs. 15 percent carbamide peroxide tooth-whitening agents

BACKGROUND: Agents with carbamide peroxide, or CP, in various concentrations are widely prescribed for at-home tooth whitening. It is not clear, however, if the more concentrated gels will whitening teeth to a greater extent, as no controlled clinical trials have been reported. The authors conducted a double-blind study of human subjects to evaluate whether a 15 percent CP tooth-whitening system was more effective than a 10 percent CP system, and to determine if tooth sensitivity increased with use of the higher concentration. METHODS: The authors recruited 57 subjects with maxillary anterior teeth of shade A3 or darker (as gauged against a value-oriented shade guide). The subjects were 18 to 65 years of age and in good general and dental health. After matching the subjects by sex and age, the authors randomly assigned them to either a control group, which used a 10 percent CP whitening agent, or an experimental group, which used a 15 percent CP agent. RESULTS: The results indicated that there was no significant difference in shade change between the groups after one week of treatment (t = 1.455, P = .05), but there was a significant difference at the end of the treatment period (t = 2.303, P < .05), as well as two weeks after treatment concluded (t = 2.248, P < .05). There was no significant difference in sensitivity (t = 1.399, P > .05). CONCLUSIONS: There was a significant difference in color change between the 10 percent CP and 15 percent CP groups at the end of the study period. There was no significant difference in level of tooth sensitivity between the two groups, and the incidence was equal; there was, however, a significant difference in variability of tooth sensitivity between the two groups. CLINICAL IMPLICATIONS: If performed under the careful guidance of a dentist, at-home whitening is an effective treatment, regardless of whether 10 percent CP or 15 percent CP is used. There may be added color change and varying sensitivity with the use of 15 percent CP.     

Brushing effect of abrasive dentifrices during at-home bleaching with 10% carbamide peroxide on enamel surface roughness

During tooth bleaching abrasive dentifrices might change the outer superficial enamel. The aim of this in vitro study was to evaluate the roughness of human enamel exposed to a 10% carbamide peroxide bleaching agent at different times and submitted to different superficial cleaning treatments. The study consisted of 60 sound human enamel slabs, randomly assigned to different treatment groups: G1--not brushed; G2--brushed with a fluoride abrasive dentifrice; G3--brushed with a non-fluoride abrasive dentifrice; and G4--brushed without a dentifrice. There were 15 enamel slabs per group. Slabs of molar teeth were obtained and sequentially polished with sandpaper and abrasive pastes. A perfilometer was used to obtain the mean of Ra value on the surface of each specimen to initial and experimental times. Bleaching was performed on the enamel surface for six hours daily. After that, each slab received a cleaning surface treatment and was stored in artificial saliva. Analysis of variance (ANOVA) and Tukey's HSD hoc analysis (alpha =0.05) revealed significant differences in roughness values over time for enamel bleached and treated with different superficial cleaning methods. G1 and G4 showed no significant differences in roughness over time, G2 and G3 showed a significant increase in the surface roughness values. This in vitro investigation showed the sole use of 10% carbamide peroxide did not alter the enamel surface roughness, but the cleaning treatments that employed the use of brushing with abrasive dentifrices resulted in a significant increase of enamel surface roughness.     

Comparison of 10% carbamide peroxide and sodium perborate for intracoronal bleaching

The purpose of this study was to compare 10% carbamide peroxide to the combination of sodium perborate and water as intracoronal bleaching agents. Forty-four extracted teeth were discolored in vitro. Bleaching agents were placed intracoronally to the level of the cemento-enamel junction for 12 days; solutions were replaced after four and eight days. Standardized slides were used to rank color changes; a colorimeter was used to quantify color change. After 12 days, 65% of the discolored teeth in the 10% carbamide peroxide group and 67% of the discolored teeth in the sodium perborate group had lightened to their original shade or lighter. While there was no statistical difference between the two treatments, sodium perborate was easier to use.     

Surface change of dental amalgam after treatment with 10% carbamide peroxide

The aim of this study was to explore the effect of bleaching agents on the release of metal ions and change in physical and chemical characteristics of amalgams. Amalgam surface changes resulting from bleaching on amalgam were assessed with inductively coupled plasma atomic emission spectrophotometer, an automatic mercury analyzer, a colorimeter, and atomic force microscopy. Analysis of the release of metal ions indicated that the bleaching agent caused more copper, tin, and mercury ions to be released into the immersion solution. Furthermore, metal ion release increased progressively as immersion time was increased from 42 to 84 hours. Morphological examination revealed no significant effects of the 10% carbamide peroxide bleaching agent on the surface morphology of any of the amalgams tested. These results demonstrated that bleaching using 10% carbamide peroxide did not adversely affect the two types of amalgam tested. In other words, a 10% carbamide peroxide bleaching agent can be safely used on a short-term basis in dentist-monitored bleaching of the dental amalgam.     

Effects of a 10% carbamide peroxide bleaching agent on rat oral epithelium proliferation

The purpose of the present study was to evaluate the influence of short course topical application of carbamide peroxide on proliferating cell nuclear antigen (PCNA) immunohistochemical expression in the oral tongue mucosa of rats. Twelve male Wistar rats were submitted to topical application of 10% carbamide peroxide on one side of the dorsal tongue once a week for three consecutive weeks. Only distilled water was applied on the control side. The animals were killed on days 0, 10, and 20 after the last application. The tongue was fixed in buffered formalin for 24 h and embedded in paraffin. Tissue blocks (3 microns) were subjected to the biotin-streptavidin amplified system for identification of PCNA. The percentage of epithelial-positive basal cells in each side of the tongue mucosa was calculated. The results demonstrated that topical application of 10% carbamide peroxide increases PCNA immunohistochemical expression on the basal layer of the oral mucosa epithelium of rats on day 0 after treatment. In conclusion, short-course use of carbamide peroxide induces transient epithelial cell proliferation of the oral mucosa of rats.