Background: Vitamin A is present in our food such as meat, dairy products, and
vegetables. A control balanced diet maintains our nutritional needs of vitamin A. Over
consumption of products as well as supplementations with vitamin
A increases the risk of hypervitaminosis A. Hypervitaminosis A has been associated with
thinning of the long bones and reducing of bone formation
Objectives: Investigation the effect of over as well as optimum doses of vitamin A on growth of mandibular condyle in rats.
Materials and Methods: Eight healthy (2month old age) male Wister albino rats weighting (274 - 375grams) were used in present study. The rats were randomly divided into 2 equal group, study and control group .Control group; rats fed a standard diet containing an optimum dose of vitamin A (12 IU/g of each pellet). Study group, rats fed a standard diet supplemented with overdose of vitaminA (1700 IU /g of each pellet). After 2months, all rats were euthanized. Blood samples were collected from rats day before euthanization and the concentration of vitamin A in serum was determined for samples. The condyles of rats were dissected out and processed for histological study and histomorphometric analysis.
Results: in the study group, the histological examination revealed marked reduction in thickness of hypertrophic zones and increase in chondroblastic zones of condylar cartilage. Bone trabeculae were thin with irregular outline. The subchondral bone showed marked bone resorption with numerous osteoclasts .
Conclusions: Hypervitaminosis A increases resorption of the bone and diminishes endochondral bone growth.