الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Vitamin A belongs to the group of fat-soluble vitamins. Dietary sources of vitamin A exist in two forms: preformed vitamin A (retinol or retinyl esters) and provitamin A carotenoids. Preformed vitamin A is animal source and abundant in eggs, liver, milk and fortified cereals, while Carotenoids is plant source and present in carrots, collards and spinach. Vitamin A is required in tiny amount for a variety of biological processes, including reproduction, embryological development, cellular differentiation, growth, immunity, and vision.
Over dose of vitamin A leads to vision problems, changes in the skin, and bone metabolism disturbance. chronic cases of hypervitaminosis A may result in liver damage and pressure on the brain. Overconsumption of vitamin A either in diet or supplementation increases reliability of hypervitaminosis A.
The mandibular condyle is a growth site in humans from birth to adulthood. The mandibular condylar cartilage provides regional adaptive growth, movable articulation and endochondral bone growth.
Several studies have shown the influence of vitamin A on bone formation, but no available data have shown the effect of vitamin A on cartilaginous mandibular condyle growth.
The present study is designed to investigate the effect of over as well as optimum dose of vitamin A on growth of mandibular condyle in Wistar albino rats at different age groups correlated with phases of mandibular condyle growth in human.