Showing papers by "Flávio Fernando Demarco published in 2009"

Over-the-counter whitening agents: a concise review

Abstract: Tooth discoloration is commonly found in the dental clinic and tooth bleaching has been considered the preferred esthetic alternative, being more conservative, safe and with predictable results. Supervised home-use of 10% Carbamide Peroxide (CP) bleaching with custom-trays is the most common bleaching procedure dispensed by dentists to their patients. The good results obtained with this technique stimulated the flourishing of new products and techniques. Over-the-counter (OTC) bleaching products appeared as a low-cost alternative to bleach discolored teeth without dentist supervision. Different OTC products are available in supermarkets, drug stores or on the Internet, including rinses, paint-on brushes, toothpastes, chewing guns, dental floss, and whitening strips. There is lack of clinical evidence regarding the safety and effectiveness of these products, being most of the studies supported by the manufacturers'. Basically, toothpastes, chewing gums, and dental floss are removal agents of superficial stains. Rinses and paint-on brushes with low levels of hydrogen peroxide have some whitening effect, but without clinical relevance. Strips present similar esthetic results and side-effects, compared to bleaching with 10% CP using trays; however, the studies have financial support from the manufacturers and were based on short term evaluations. Legislation varies widely in different countries regarding OTC dental bleaching. Concerns have appeared due to the potential abusive use of these self-medication agents, especially in young patients, with potential harmful results. Dentists should be acquainted with this kind of products to be able to inform their patients. In conclusion, there is a need for independent clinical trials to provide sufficient evidence regarding the use of OTC bleaching products.

Influence of microleakage, surface roughness and biofilm control on secondary caries formation around composite resin restorations: an in situ evaluation

Abstract: This study was carried out to evaluate in situ the influence of microleakage, surface roughness and biofilm control on caries formation around composite resin restorations. During 28 days, 12 volunteers wore palatal devices containing bovine enamel slabs restored with composite resin. Restorations were made without leakage, when the adhesive system was applied, or with leakage, when adhesive system was omitted. Half of the restorations in each group were finished and the remaining were finished and polished. In one side of the palatal device, biofilm was left to accumulate over the restored slabs, and in the other side dental slabs were brushed, to allow biofilm removal. There was an extraoral application of 20% sucrose solution (8x/day) over the enamel slabs. The formation of caries lesions (white spots) was evaluated by visual inspection under stereomicroscopy. Additionally, the dental slabs were sectioned and observed under polarized light microscopy. Data were submitted to Kruskal-Wallis test and Spearman's correlation test at 5% significance level. Polishing and bonding were not significant factors regarding white spot formation (p>0.05). Biofilm control (brushing) was associated with reduction of caries formation close to the restorations (p<0.01). Polarized light microscopy confirmed the visual inspection findings. These results suggest that while microleakage and surface roughness did not influence caries lesion formation, biofilm control may prevent the enamel demineralization.

A Double-Blind Randomized Controlled Clinical Trial of 10 Percent Versus 16 Percent Carbamide Peroxide Tooth-Bleaching Agents: One-Year Follow-up

Abstract: Background The use of high-concentration tooth-bleaching agents has been associated with increased longevity of the whitening effect. The authors conducted a randomized controlled clinical trial to evaluate the longevity of the whitening effect at one year of two at-home tooth-bleaching agents. Methods The authors randomly assigned 92 participants with a mean shade of C1 or darker for six maxillary anterior teeth into two equal-sized groups according to carbamide peroxide concentration: 10 percent (CP10) or 16 percent (CP16). Treatment involved the use of a whitening agent in a tray for two hours daily for three weeks. The authors evaluated tooth shade with a shade guide and a spectrophotometer at baseline and one week, six months and one year after bleaching. Participants in both groups answered questions about their dietary and oral hygiene behaviors. Results At the one-year recall appointment, the teeth in both groups remained significantly lighter than at baseline. At this time, participants from the CP10 and CP16 groups consumed staining beverages and foods at a level as high as at the six-month recall appointment, and this consumption level was not statistically significant between groups ( P > .5). Conclusions One year after bleaching, both treatment groups had the same median tooth shade, which remained lighter than at baseline. Clinical Implications Higher carbamide peroxide concentration does not increase the longevity of the whitening effect of at-home tooth-bleaching agents.

Buccal cells submitted to three different storage conditions before DNA extraction

Abstract: This study evaluated quantitatively and qualitatively the effect of the storage time of samples before the application of the cell lysis solution (CLS) for extracting DNA from buccal cells (BC). BC from the upper and lower gutter region were collected from 5 volunteers using special cytobrushes (Gentra), totaling 3 collections for each individual. In the control group (n=10), CLS was applied soon after BC collection. In the other two groups, samples were stored at room temperature (n=10) or at 4°C (n=10). After CLS application, DNA was extracted according to the manufacturer's instructions (Puregene DNA Buccal Cell Kit; Gentra Systems, Inc.). The DNA obtained was evaluated by two calibrated blind examiners using spectrophotometry and analysis of DNA bands (0.8% agarose gel electrophoresis). The obtained data were submitted to one-way ANOVA. The means and standard deviations for DNA extracted under immediate, room temperature and cooling temperature conditions were 3.5 ± 0.7, 3.0 ± 0.6 and 4.1 ± 1.8 µg, respectively (p=0.385). No significant differences were found in relation to the amount of DNA for the different storage conditions. However, in the visual analysis of the DNA bands, no trace of DNA degradation was detected when CSL was applied soon after DNA collection, while DNA bands with degradation could be observed in the other groups. Within the limitations of the study, it may be concluded that CLS should be applied soon after DNA collection in order to obtain high-quality DNA from BC.

Comparison between DNA obtained from buccal cells of the upper and lower gutter area.

Abstract: This study compared quantitatively and qualitatively the DNA extracted from buccal cells collected from the upper or lower gutter areas. Buccal cells were collected from the upper (n=15) and lower gutter (n=15) region from 15 volunteers using a special cytobrush (Gentra), totaling 2 collections from each individual. DNA was extracted from the samples according to the manufacturer's instructions. The DNA obtained was qualitatively and quantitatively evaluated by 2 calibrated blind examiners using spectrophotometry and analysis of DNA bands (0.8% agarose gel electrophoresis). Data was statistically analyzed by one-way ANOVA (?=0.05). Means and standard derivation (SD) for total DNA yield from the upper and lower gutter area were 12.2 ?g (12.0) and 9.4 ?g (8.5), respectively (p=0.821). There was higher (p<0.05) DNA purity for the upper gutter (1.79; 0.05) when compared to lower gutter area (1.66; 0.10). Regarding to the DNA quality, no differences were observed between the 2 location sites, but all samples showed similar degree of degradation. In conclusion, it would be recommendable that buccal cells for DNA extraction be collected from the upper gutter area in the attempt to increase DNA purity.

Effect of blood contamination and decontamination procedures on marginal adaptation and bond strength of composite restorations

Abstract: Purpose: To evaluate the effect of blood contamination and different decontamination procedures on marginal adaptation and bond strength of a two-step total-etch adhesive system to dentin. Methods: A total of 135 bovine incisors had the labial surfaces ground to receive cylindrical cavities, and were randomly divided into a control and 8 experimental groups (n=15) according to contamination and decontamination procedures. Freshly collected human blood was applied onto the cavity either before or after light-curing of the adhesive. Four decontamination protocols were tested (drying with paper, water rinsing, phosphoric acid etching, and 10% NaOCl rinsing). The cavities were restored with Adper Single Bond and Filtek Z250 (3M ESPE). The specimens were subjected to thermal cycling before the dye staining test. The cavity floor was removed and the restorations were subjected to a push-out test. Data were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results: Blood contamination after adhesive light-curing increased marginal gap and yielded lower push-out bond strength values (P<0.01). Conclusion: Water rinsing seems to be a reliable procedure for cavity decontamination. The decontamination procedures tested do not recover marginal sealing and bond strength when blood contamination occurs after light-curing of the adhesive.

Nonvital tooth bleaching with halogen light-activated agents: case reports and discussion.

Abstract: Esthetic dentistry has received increased attention in recent years, as people are more aware of the esthetic appearance of their teeth, including alignment and whiteness. This development, combined with a decrease in the incidence and severity of caries, has directed some clinicians toward conservative and non-invasive treatments such as tooth bleaching. A number of methods for nonvital tooth bleaching are described in the literature; these procedures rely on the bleaching agent used, the agent's concentration, product format, and the source of light activation. This article presents two case reports in which dental bleaching with halogen light-activated agents was used to treat a nonvital discolored incisor. The advantages and disadvantages of the technique are discussed.