Effects of inorganic mercury exposure in the alveolar bone of rats: an approach of qualitative and morphological aspects.

BACKGROUND: In comparison to organic mercury (MeHg), the environmental inorganic mercury (IHg) can be found in some skin-lightening cosmestics were considered "harmless" for a long time. However, recent studies have shown that long-term exposure to low doses of IHg may affect biological systems. Therefore, this study investigated the effects of IHg long-term exposure to the alveolar bone of adult rats. METHODS: Adult Wistar rats were distributed in control and HgCl2 exposed (0.375 mg/kg/day). After 45 days, the rats were euthanized and both blood and hemimandibles were collected. Total blood Hg levels were measured and both inorganic and organic components of the alveolar bone were determined through XRD and ATR-FTIR. The microstructure of the alveolar bone was assessed by using micro-CT and the morphometric analysis was performed by using stereomicroscopy. RESULTS: Alterations in the physicochemical components of the alveolar bone of exposed animals were observed. The bone changes represented a tissue reaction at the microstructural level, such as bone volume increase. However, no significant dimensional changes (bone height) were observed. CONCLUSION: Exposure to IHg at this dose can promote microstructural changes and alteration in the organic and inorganic components in the alveolar bone.

Ethanol binge drinking exposure affects alveolar bone quality and aggravates bone loss in experimentally-induced periodontitis.

BACKGROUND: Periodontitis is a multifactorial inflammatory disease of tooth supporting tissues caused by oral biofilms, influenced by environmental and genetic factors, among others. Ethanol consumption has been considered a factor that enhances alveolar bone loss, especially in high doses. The present study aims to investigate the changes promoted by ethanol binge drinking per se or associated with ligature-induced periodontal breakdown on alveolar bone loss. MATERIALS AND METHODS: Thirty-two Wistar rats were randomly allocated into four groups: control (C), ethanol (3g/kg/day; 3 days On-4 days Off protocol by gavage for 28 days, EtOH), experimental periodontitis (EP) and experimental periodontitis plus ethanol administration (EP+EtOH). On day 14th, periodontitis was induced by ligatures that were placed around the lower first molars. On day 28th, the animals were euthanized and mandibles were submitted to stereomicroscopy for exposed root area analysis and micro-computed tomography (micro-CT) for the evaluation of alveolar bone loss and microstructural parameters. RESULTS: The results revealed that ligature-induced alveolar bone loss is aggravated by ethanol binge drinking compared to controls (1.06 ± 0.10 vs 0.77 ± 0.04; p<0.0001). In addition, binge drinking per se altered the alveolar bone quality and density demonstrating a reduction in trabecular thickness, trabecular number parameter and bone density percentual. Periodontal disorder plus ethanol binge drinking group also demonstrated reduction of the quality of bone measured by trabecular thickness. CONCLUSIONS: In conclusion, intense and episodic ethanol intake decreased alveolar bone quality in all microstructural parameters analyzed which may be considered a modifying factor of periodontitis, intensifying the already installed disease.

Is There Association Between Stress and Bruxism? A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to investigate a possible association between stress and bruxism in humans. This study was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines under the code CRD42020188862, and the searches were performed on the following databases: PubMed, Scopus, Web of Science, Cochrane, LILACS, OpenGrey, and Google Scholar. This systematic review evaluated observational studies in adult humans with and without stress to verify the association between bruxism and the presence of stress. The risk of bias was evaluated through the Joanna Briggs Institute Critical Appraisal Tools for Analytical Cross-Sectional Studies. In quantitative analysis, the Odds Ratio (OR) and their 95% confidence interval (CI) were calculated through a fixed-effect model. Furthermore, a summary of the overall strength of evidence was presented using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). A total of 1,458 studies were identified, and six were included in this systematic review. Two studies included were classified with a low risk of bias, and the others were classified with a moderate risk of bias. In three articles, a meta-analysis was performed and showed an association between these two factors (OR 2.07 [1.51, 2.83], p < 0.00001, I 2 = 45%). Besides that, a low certainty of the evidence was detected among this association. Stressed individuals show a higher chance of presenting bruxism when compared to healthy individuals. Despite the low heterogeneity found in the quantitative analysis among the articles reporting an association between stress and bruxism, further studies with similar methods are necessary to understand this relationship better.