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Comparison between two experimental protocols to promote osteoporosis in the maxilla and proximal tibia of female rats

Author(s): Teófilo Juliana Mazzonetto | Azevedo Ana Carolina Bernardes | Petenusci Sérgio Olavo | Mazaro Renata | Lamano-Carvalho Teresa Lúcia

Journal: Pesquisa Odontológica Brasileira
ISSN 1517-7491

Volume: 17;
Issue: 4;
Start page: 302;
Date: 2003;
Original page

Keywords: Osteoporosis | Tibia | Maxilla | Ovariectomy

The effects of two experimental protocols (ovariectomy associated or not with a low calcium diet) used to promote osteoporosis in the rat maxilla and proximal tibia were compared 5 and 11 weeks after surgery. Female Wistar rats were ovariectomized or sham-operated. Half of the ovariectomized rats were fed a low Ca++ diet (ovx*) and the remaining ovariectomized (ovx) and sham animals received a standard chow. At sacrifice, the proximal metaphysis was excised from the tibia and the molars were extracted from the hemi-maxilla. Dry (60°C overnight) and ash (700°C/14 h) weights were measured and the ashes were used for Ca++ measurement by means of a colorimetric method. After 5 weeks, ovx caused no alteration while ovx* decreased proximal metaphysis (17%) and maxilla (35%) bone mass. After 11 weeks, ovx caused a 14% bone mass reduction in the proximal metaphysis but not in the maxilla, while ovx* caused a comparable bone mass reduction (30%) in both bone segments. Calcium concentration was not altered in any experimental condition. The results show that estrogen deficiency is insufficient to cause maxillary osteoporosis in rats over an 11-week period and a long-term ovariectomy is needed to exert deleterious effect on proximal metaphysis bone mass. When a low Ca++ diet is associated with estrogen deficiency, however, a relatively precocious harmful effect is observed, twice as pronounced in the maxilla than in the proximal metaphysis. On a long-term basis, ovariectomy associated with a low Ca++ diet seems to be equally injurious to both proximal metaphysis and maxilla.

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Tangokurs Rapperswil-Jona

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