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Induction and pharmacological treatment of oral osteopenia in rats.

BACKGROUND
Osteoporosis is a major public health problem, responsible for a great number of fractures, associated with devastating costs to society. In addition, oral bone loss has an enormous impact on the health quality of life of patients, affecting up to 90% of elderly individuals. The aim of this work was to elaborate an animal model of mandibular and maxillary osteoporosis in which to evaluate bone loss and possible prevention by pharmacological treatment.


METHODS
Six Sprague-Dawley rats were gonadectomized and treated with clodronate (male) or 17 beta-estradiol (female) for two months. Six gonadectomized and six sham-operated rats of both sexes were treated with placebo. The mandible and maxilla, fixed and methacrylate embedded, were serially sectioned, microradiographed and processed for histomorphometric analysis.


RESULTS
Gonadectomy did not modify the amount of compact and trabecular bone in mandibles of rats of either sex, treated or not with clodronate or estrogens, compared to sham-operated rats. Compared to sham-operated rats, a 10-25% increase of bone porosity was found in the maxilla of ovariectomized rats, either receiving estrogens or not, while in male rats no difference among groups could be evidenced.


CONCLUSIONS
The conclusion is drawn that rats, due to their peculiar masticatory habits yielding huge loads on oral bones, do not represent a suitable experimental model for studying oral bone loss related to skeletal osteoporosis. In order to worsen oral osteopenia it would be mandatory to combine gonadectomy with a mechanical unloading (i.e. after molar extraction) of mandibular or maxillary bone.