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Effect of ovariectomy on maxilla and mandible dimensions of female rats.

OBJECTIVE
The role of estrogen in craniofacial growth still remains unclear. Therefore, the present study aimed to assess the effect of estrogen deficiency on maxilla and mandible dimensions.


SETTING AND SAMPLE POPULATION
The study was conducted at the Department of Pediatric Dentistry at the School of Dentistry of Ribeirão Preto, University of São Paulo, and used forty female Wistar rats.


MATERIAL AND METHODS
Ovariectomy (OVX) and placebo surgery (Sham) were performed when animals were twenty-one-day-old (prepubertal stage). Dimensions of the maxilla and mandible were assessed by craniometric analysis using radiographs, during and after puberty of the animals (45- and 63-day-old, respectively). Quantitative real-time PCR and immunohistochemical analyses were performed to determine the expression and localization, respectively, of estrogen receptor-alpha (ERα) and -beta (ERβ) in different growth sites of the evaluated structures at puberty. The differences between the groups for each outcome were evaluated using the t test with an established alpha error of 5%.


RESULTS
There were significant differences between the OVX and Sham groups for horizontal and vertical linear measurements in the maxilla and the mandible at both pubertal and post-pubertal stages (p<0.05). The ovariectomized rats showed significantly greater measures for all dimensions assessed. No differences in gene expression of ERα and ERβ were identified at the different growth sites between the OVX and Sham groups (p>0.05). Immunohistochemical analyses revealed the presence of both estrogen receptors in osteoblasts and chondrocytes in the midpalatal suture and mandibular condyle, respectively, in the OVX and Sham groups.


CONCLUSION
Our results suggest that estrogen deficiency from the prepubertal stage might increase the growth of the maxilla and mandible in female rats.