Effect of sex steroids on bone formation in an orthopedically expanded suture in rats

Objective The purpose of this work was to evaluate the effects of sex steroids on bone formation in response to midpalatal suture expansion by means of histological and immunohistochemical examinations and computed tomography (CT). Materials and methods A total of 32 male and 32 female 12-week-old Wistar rats were divided into four groups per gender. Testosterone was administered to the castrated experimental male rats, estrogen to castrated experimental female rats. Saline solution was given subcutaneously to the male and female control, sham, and castration groups during expansion and retention periods, which lasted 7 and 5 days, respectively. The expansion amount was measured with a digital caliper. The density of the new bone in the expansion area was measured via CT. Results Histological and CT evaluation revealed that the number of osteoblasts and density of the new bone was higher in male and female experimental groups than in all the other groups. When scores of staining intensity were compared, the experimental groups demonstrated statistically significant greater immunoreactivity in the osteoblasts compared to castrated-only groups. Bone density was higher in the female experimental group than in the others, and higher in the male experimental group than in the others. Expansion amounts in the castrated groups were higher than in the others (p < 0.05). Conclusion Raising the levels of sex steroids in rats revealed positive effects on bone formation in the midpalatal suture in response to expansion. Increased sex steroid levels can reduce the time needed for retention.