Acute effects of ovariectomy on wound healing of alveolar bone after maxillary molar extraction in aged rats

Acute effects of ovariectomy on the bone wound healing processes after maxi llary molar extraction in aged rats were examined by means of quantitative scanning electron microscopy (SEM), backscattered electron image (BSE) anal ysis and energy-dispersive X-ray (EDX) microanalysis. Six-month-old female rats underwent either sham operation or bilateral ovariectomy, and 7 days p ostoperatively, the maxillary first molars were extracted. On post-extracti on days 7, 30 and 60, the dissected maxillary bone surfaces were examined b y SEM to reveal the bone formative and resorptive areas around the extracte d alveolar sockets. In addition, the resin-embedded maxillae were micromill ed in the transverse direction through the extracted alveolar sockets, and the newly-formed bone mass on the buccal bone surfaces and within the extra cted sockets was examined by BSE analysis. Compared with sham-operated cont rols, the extent of newly-formed bone mass on the buccal bone surfaces in O VX rats was significantly decreased, due to increased bone resorption. On t he other hand, new bone formation within the extracted sockets was similar in the experimental groups. In EDX microanalysis of these newly-formed bone matrices, both Ca and P weight % and Ca/P molar ratio were similar in the experimental groups. Our results suggest that 1) acute estrogen deficiency induced by ovariectomy stimulates sustained bone resorption, but has less e ffect on bone formation, and 2) bone wound healing after maxillary molar ex traction within extracted alveolar sockets is not significantly delayed by ovariectomy, but bony support by newly-formed bone mass on the maxillary bo ne surfaces at the buccal side of the extracted sockets is significantly de creased, due to increased bone resorption. Anat Rec 262: 203-212, 2001. (C) 2001 Wiley-Liss, Inc.