Mineral trioxide aggregate (MTA) and Portland cement are being used in dentistry as root end-filling materials. However, biocompatibility data concerning genotoxicity and cytotoxicity are needed for complete risk assessment of these compounds. In the present study, genotoxic and cytotoxic effects of MTA and Portland cements were evaluated in vitro using the alkaline single cell gel (comet) assay and trypan blue exclusion test, respectively, on mouse lymphoma cells. The results demonstrated that the single cell gel (comet) assay failed to detect DNA damage after a treatment of cells by MTA and Portland cements for concentrations up to 1000 g/ml. Similarly, results showed that none of the compounds tested were cytotoxic. Taken together, these results seem to indicate that MTA and Portland cements are not genotoxins and do not induce cellular death.

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The goal of this study was to analyze the role of cyclo-oxygenase-2 following bone repair in rats submitted to low-level laser therapy. A total of 48 rats underwent surgery to inflict bone defects in their tibias having been randomly distributed into two groups: negative control and laser exposed group, i.e., the animals were treated with low-level laser therapy by means of gallium arsenide laser at 16 J/cm(2). The animals were killed after 48 h, 7 days, 14 days, or 21 days. The tibias were removed for morphological, morphometric, and immunohistochemistry analysis for cyclo-oxygenase-2. Statistical significant differences (P < 0.05) were observed in the quality of bone repair and quantity of formed bone between groups 14 days after surgery in the laser exposed group. In the same way, cyclo-oxygenase-2 immunoreactivity was more intense in bone cells for intermediate periods evaluated in this group. Taken together, such results suggest that low-level laser therapy is able to improve bone repair in the tibia of rats after 14 days of surgery as a result of an up-regulation for cyclo-oxygenase-2 expression in bone cells.

The purpose of this study was to investigate the effects of Bioglass 45S5Ò and Biosilicate Ò , on bone defects inflicted on the tibia of rats. Fifty male Wistar rats were used in this study, and divided into five groups, including a control group, to test Biosilicate Ò and Bioglass Ò materials of two different particle sizes (180-212 lm or 300-355 lm). All animals were sacrificed 15 days after surgery. No significant differences (P [ 0.05) were found when values for Maximal load, Energy Absorption and Structural Stiffness were compared among the groups. Histopathological evaluation revealed osteogenic activity in the bone defect for the control group. Nevertheless, it seems that the amount of fully formed bone was higher in specimens treated with Biosilicate Ò (granulometry 300-355 lm) when compared to the control group. The same picture occurred regarding Biosilicate Ò with granulometry 180-212 lm. Morphometric findings for bone area results (%) showed no statistically significant differences (P [ 0.05) among the groups. Taken together, such findings suggest that, Biosilicate Ò exerts more osteogenic activity when compared to Bioglass Ò under subjective histopathological analysis.

Taken together, these results indicate that panoramic dental radiography might not induce chromosomal damage, but may be cytotoxic. Overall, the results reinforce the importance of evaluating the health side effects of radiography and contribute to the micronucleus database, which will improve our understanding and practice of this methodology in children.

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Our results indicate that laser therapy improves bone repair in rats as depicted by differential histopathological and osteogenic genes expression, mainly at the late stages of recovery.