Ultrastructural study of the periodontal ligament of dog's deciduous teeth after repeated injections by cadmium chloride

ABSTRACT

The effect of cadmium administration on the histogenesis of the periodontal ligament [PL] of dog deciduous teeth were studied by light and electron microscopic technique. Ten pregnant female dogs were divided into two groups, 5 animals for each. In group I, the dogs were injected with 0.5 mL of physiological saline and used as control. In the group II, the dogs were injected with cadmium chloride [l0mg/kg body weight] at three times intervals weekly. The periodontal ligament of deciduous anterior teeth of new born, at one month old age, were examined. According to our observations, the cadmium has harmful degenerative effect on periodontal ligament. Followed by regenerative response. The process was divided into two main stages. .1- During the first stage, prominent degenerative events took place in the periodontal ligament fibres. However, the blood vessels and nerves remained intact and were not affected. Phagocytosis and removal of necrotic material were well advanced and followed by marked regeneration of collagen fibres of periodontal ligament. 2- During the second stage, two populations of regenerating collagen fibres, based on the predominant cell type present, were observed in the tissue. One of apparently normal fibres located in areas where blood vessels and nerves were abundant and not affected. The other population of groups of regenerative fibres showing fibrotic tissue and collagen. This second type of fibres was predominant in areas where the number of blood vessels was greatly reduced and affected