Buccal cells submitted to three different storage conditions before DNA extraction

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 percent 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.

Influence of cavity configuration on the microleakage of resin composite root-end fillings

The purpose of the present study was to evaluate, in vitro, the effect of three different cavity configurations on the microleakage of resin composite root-end fillings. Conventional root therapy was peformed in 60 anterior human teeth. Apicectomies were made, teeth were randomly divided in three groups and the apical cavities were prepared as following: Group 1 - classic Class I cavities; group 2 - saucer-shaped cavities; group 3 - adhesive cavities (round angles). The cavities were prepared with high speed pieces under air-water cooling and burs were replaced after four preparations. All cavities were restored with a self-etching adhesive system (Clearfil SE Bond, Kurakay) and a hybrid resin composite (Filtek Z-250, 3M Espe®). Teeth were isolated with two coats of nail varnish, except for the apical region, and immersed in methylene blue for 14 days, at 37ºC. Specimens were washed, sectioned and evaluated for absence or presence of dye penetration, in a stereomicroscope (40 X). Data were subjected to statistical analysis using Kruskal-Wallis test, with p<0.05. The degree of dye leakage was low in all groups (75-90% leakage-free specimens). No statistically significant difference was found between the three groups (p>0.05). Within the limitations of this study, cavity configuration did not have influence on microleakage of composite restorations used in root-end cavities.