Maxillary molar extraction causes increased bone loss in the mandible of ovariectomized rats

Abstract

Although osteoporosis is a major public health concern, its effect on oral bone has not been determined. More important may be the effect of estrogen depletion on the response of oral bone to dental treatments such as tooth extraction or pathologic processes such as periodontal disease. Our objective was to determine if maxillary molar extraction increases mandibular bone loss in the ovariectomized compared with a sham‐operated control. Fifty‐three ovariectomized and 53 sham‐operated 6‐month‐old Sprague‐Dawley rats were randomly assigned to the following groups: (1) ovariectomized, adult; (2) sham‐operated, adult; (3) ovariectomized, adult, extraction; (4) sham‐operated, adult, extraction; (5) ovariectomized, old; (6) sham‐operated, old; (7) ovariectomized, old, extraction; and (8) sham‐operated, old, extraction. Fourteen days following ovariectomy, the extraction groups had their bilateral maxillary molars extracted. The adult and old rats were sacrificed 114 and 200 days postovariectomy, respectively. The right mandible was tested to failure in three point bending. The bone mineral density (BMD) of the left mandible was measured with high resolution dual energy X‐ray absorptiometry. The area fraction and area moment of inertia of mandible sections were determined using image processing software. In the ovariectomized rats, maxillary molar extraction resulted in decreases (p < 0.05) in the failure load (21%), stiffness (39%), BMD (3%), and bone area fraction (8%) of the mandible. However, in the sham‐operated rats, these decreases following maxillary molar extraction were less (p < 0.05) than those in the ovariectomized rats and only present in the mandibles of the aged rats. Therefore, maxillary molar extraction resulted in a more rapid decrease in structural properties and BMD and a larger decrease in bone area fraction of the mandible in ovariectomized rats compared with those in sham‐operated rats. These findings indicate that oral bone loss that occurs as a result of pathologic conditions or dental treatments may be accelerated in individuals who have estrogen depletion. (