Bone mineral density of alveolar bone in rats during pregnancy and lactation

Background: The present study was designed to investigate the effect of pregnancy and lactation on the bone mineral density (BMD) of alveolar bone in rats fed diets containing different amounts of calcium (Ca). The effects of different levels of Ca intake by the mothers on the BMD of alveolar bone in their pups were also examined. Methods: Ten-week-old female Wistar rats were housed with male rats for breeding and were divided into 3 groups fed diets containing 0.9, 0.3, and 0.02% Ca, respectively. They were further divided into 2 groups according to pregnancy or non-pregnancy. Animals in the pregnant group were raised with their own pups for lactation. After the experiment, all animals were sacrificed, their mandibles were dissected, and soft x-ray microradiographs were taken to determine BMD in the interdental area with an image analyzer. Results: In both groups, BMD in alveolar bone decreased based on the amount of Ca in the diet, but the magnitude of this decrease was much greater in the pregnant group than in the non-pregnant group. There was no significant difference in BMD between 2 groups fed a 0.9% Ca diet. The BMD of alveolar bone in the pups also decreased depending on the amount of Ca in the diet. Conclusions: The above results suggest that pregnancy and subsequent lactation could be risk factors for alveolar bone loss, especially under conditions of Ca insufficiency or deficiency and that Ca insufficiency or deficiency in the mother caused decreases in the BMD of alveolar bone in the pups.