Effects of estrogen deficiency during puberty on maxillary and mandibular growth and associated gene expression - an µCT study on rats.

BACKGROUND: Estrogen is a well-known and important hormone involved in skeletal homeostasis, which regulates genes involved in bone biology. Some studies support that estrogen is important for craniofacial growth and development. Therefore this in vivo animal study aimed to investigate, whether and in which way low estrogen levels in the prepubertal period affect craniofacial development in the postpubertal stage and to quantify the gene expression of RANK, RANKL and OPG in cranial growth sites in ovariectomized estrogen-deficient rats during puberty. METHODS: Control (sham-operated, n = 18) and ovariectomy (OVX, n = 18) surgeries were performed on 21-days-old female Wistar rats. Animals euthanized at an age of 45 days (pubertal stage) were used for gene expression analyses (n = 6 per group) and immunohistochemistry of RANK, RANKL and OPG. Animals euthanized at 63 days of age (post-pubertal stage) were used for craniofacial two-dimensional and three-dimensional craniofacial measurements using µCT imaging (n = 12 per group). RESULTS: In the µCT analysis of the mandible and maxilla many statistically significant differences between sham-operated and OVX groups were observed, such as increased maxillary and mandibular bone length in OVX animals (p < 0.05). Condylar volume was also significantly different between groups (p < 0.05). The sham-operated group showed a higher level of RANK expression in the midpalatal suture (p = 0.036) and the RANKL:OPG ratio levels were higher in the OVX group (p = 0.015). CONCLUSIONS: Our results suggest that estrogen deficiency during the prepubertal period is associated with alterations in the maxillary and mandibular bone length and condylar growth.

Estrogen deficiency affects tooth formation and gene expression in the odontogenic region of female rats.

BACKGROUND: There is some evidence that estrogen regulates the expression of several genes in different cells, including dental cells. Therefore, the aim of this study was to investigate the role of estrogen deficiency during tooth development regarding tooth structure morphology and its impact on the expression of odontogenesis-related genes. METHODS: A total of 40 female Wistar rats was divided into OVX (estrogen deficiency) and Sham (control) groups. Bilateral ovariectomy was performed in the OVX group, while Sham surgery was performed in the control group at the age of 21 days. At an age of 56 days, 16 rats were euthanized for gene expression analyses of Bmp4, Smad6, Tgfb1 and Runx2. At the age of 63 days, the remaining rats were euthanized for histological and morphometric analyses of teeth. The mandibles of the rats were submitted to µCT analysis. Tooth structures (enamel, dentin and dental pulp) were analyzed. T test was used to compare the mean differences between groups (p<0.05). RESULTS: In the µCT analysis, enamel and dentin thickness were significantly increased in the control group (p<0.0001). Pulp dimensions were significantly larger in the OVX group (p<0.0001). A reduction of tooth structures in the OVX group was confirmed in HE staining. Smad6 was differentially expressed in the OVX group (p=0.04). CONCLUSION: Estrogen deficiency affects gene expression in the odontogenic region and tooth structure morphology.

The role of postnatal estrogen deficiency on cranium dimensions.

OBJECTIVES: The aim of this study was investigate the cranium dimensions of adult female rats, who suffered estrogen deficiency during the prepubertal stage, to assess the impact of estrogen deficiency on craniofacial morphology. MATERIAL AND METHODS: Twenty-two female Wistar rats were divided into ovariectomy (OVX) (n = 11) and sham-operated control (n = 11) groups. Bilateral ovariectomy were performed in both groups at 21 days old (prepubertal stage), and rats were euthanized at an age of 63 days (post-pubertal stage). Micro-CT scans were performed with rat skulls, and the cranium morphometric landmark measurements were taken in the dorsal, lateral, and ventral view positions. Differences in measurements between the OVX and sham control groups were assessed using t test with an established alpha error of 5%. RESULTS: The measures of the rats' skull showed that the inter-zygomatic arch width and anterior cranial base length were significantly larger in OVX group (p = 0.020 and p = 0.050, respectively), whereas the length of parietal bone was significantly higher in the sham group (p = 0.026). For the remaining measurements no significant differences between groups were detected (p > 0.05). CONCLUSION: This study provides evidence that ovariectomized rats had alterations in cranial bone dimensions, demonstrating that estrogens during puberty are important for skull morphology. CLINICAL RELEVANCE: To understand the role of estrogen on the postnatal cranium development will impact the clinical diagnose and therapy during childhood and adolescence.

Association between Pulp Stones and Kidney Stones: A Systematic Review and Meta-analysis.

INTRODUCTION: A systematic review and meta-analysis were performed to evaluate the association between pulp stones and kidney stones. METHODS: A search for observational studies was performed in PubMed, Scopus, Web of Science, Biblioteca Virtual em Saúde, and the gray literature. The Newcastle-Ottawa Scale for Risk of Bias criteria were used to evaluate the internal quality of the included studies. A fixed-effects meta-analysis was performed to evaluate the association between the conditions. RESULTS: A total of 213 studies were identified after the removal of duplicates. Of these, 9 studies were selected after screening the titles and abstracts. Finally, after full-text reading for qualitative analysis, 7 studies were selected, and of these, 2 were used in the meta-analysis. A significant association was found between pulp stones and kidney stones (1.97 [95% confidence interval, 1.21-3.18]; P < .05). CONCLUSIONS: This study revealed an association between pulp stones and kidney stones. Further well-designed studies should be conducted in order to confirm whether pulp stones are predictive indicators of undiagnosed kidney stones.