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.

Is the use of contraceptives associated with periodontal diseases? A systematic review and meta-analyses

BACKGROUND

Previous studies indicated an impact of hormonal contraceptive use on oral health. This systematic review aimed to investigate the evidence supporting the impact of the use of hormonal contraceptives and periodontal diseases.

METHODS

This study is based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and based on the PECO acrostic. Inclusion criteria comprised observational studies including women (P), which evaluated hormonal contraceptive users (E) and hormonal contraceptive non-users (C), to verify the association between this hormonal therapy and the periodontal diseases (O). Searches were performed on 5 databases: PubMed, Scopus, Web of Science, Cochrane Library, LILACS and grey literature (OpenGrey and Google Scholar). After the selection process, the included studies were evaluated qualitatively. Moreover, quantitative data were analyzed in two meta-analyses for clinical attachment loss (CAL) and probing depth (PD). Finally, the level of certainty was measured with the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) tool between periodontal clinical parameters.

RESULTS

18 articles were eligible for the qualitative synthesis and 7 of them were selected for quantitative analysis. Hence, 15 of the eligible articles reported an association between the use of hormonal contraceptives and severity of periodontal disease. However, 6 articles demonstrated high risk of bias and were excluded from quantitative synthesis. The meta-analysis showed a statistically significant difference for CAL (MD 0.24 [0.09, 0.40]; p = 0.002), but in PD (MD 0.05 [- 0.05, 0.15]; p = 0.33) such difference was not identified. A very low level of evidence was found between the clinical parameters.

CONCLUSIONS

The use of hormonal contraceptives may be associated to severity of periodontal diseases. However, the quantitative analysis points to an inconclusive outcome due to the high level of heterogeneity. The association is biologically plausible, however additional studies are warranted to better elucidate the clinical significance of this possible association.

Aluminum-Induced Toxicity in Salivary Glands of Mice After Long-term Exposure: Insights into the Redox State and Morphological Analyses

Several studies indicate aluminum (Al) as a potent toxicant, mainly related to central nervous system disorders. However, investigations about the Al effects over salivary glands are still scarce. In this way, the present study aimed to investigate whether the Al chloride (AlCl₃) is able of triggering oxidative stress in parotid and submandibular glands of mice and also, if any morphological impairment is observed. For this, twenty mice were divided into two groups: Exposed group (EG), which received 18.5 mg/kg of AlCl₃ by intragastric gavage for 60 days and control group (CG), which received distilled water by intragastric gavage during the same period of time. After that, levels of reduced glutathione (GSH) and malonaldehyde (MDA) were analyzed and we performed morphological analyses by evaluating the area of parenchyma, stroma, acini, and ducts in both glands. Statistical analyses were performed by Student's t test and two-way ANOVA, adopting p < 0.05. No abnormal body weight was observed and data indicates that although both major salivary glands are susceptible to Al-induced oxidative stress, by increasing MDA and reducing GSH, only submandibular glands decreased the parenchyma and increased stroma area. Moreover, the submandibular glands showed smaller total area of acini and higher total area of ducts, in comparison with the control group. Notably, AlCl₃ induces oxidative stress in both glands, however, submandibular glands showed to be more susceptible to Al effects than parotid glands. Our study gives evidences about Al toxicity in parotid and submandibular glands and claims for new investigations to understand more mechanisms of Al-induced toxicity.