実験的歯根近接が歯および歯周組織に及ぼす影響
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概要
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The purpose of present study is to evaluate the histological changes of the periodontal tissue under orthodontic root proximity. Twelve adult mongrel dogs were divided into 14-, 30-, 60- and 90-day groups. The root of a right mandibular second incisor was brought closer orthodontically to the root of a third incisor. Orthodontic force of 40 g was applied at installation of the appliance in the 14- and 30-day groups and at installation of the appliance and every 30 days thereafter in other groups. After the teeth had moved, histological sections along mesio-distal axis were made and the tissue around the proximized roots were examined histopathologically. In addition, the distances around the tissue were measured. The following results were obtained : 1. When the root proximity was induced by orthodontic tooth movement, the width of periodontal membrane space remained almost constant at sites the interalveolar septa existed. And the interalveolar septa disappeared when the interradicular distance became about twice as much as the width of the periodontal membrane space. 2. In all experimental groups, the slight increase of immature fibroblasts and the vascularization were observed in the tissue of periodontal membrane as the interradicular distance were shorten. When the interradicular distance became shorter than the width of the periodontal membrane space where the interalveolar septa exists, significant changes of tissue remodeling such as vascularization and immature granulation tissue were observed. 3. When root proximity occurred, the periodontal membrane was compressed and degenerated according to a decrease of the interradicular distance, and then the interalveolar septa disappeared. Even at sites where the interradicular distance were the shortest and root resorption was proceeding actively, the periodontal membrane did not disappear completely but remained as a single layer of degenerated tissue lying between the roots. Consequently it is considered that when the orthodontic force is applied and the interradicular distance become shorter, the resorption of interalveolar septa and roots may act to compensate the space for peridontal membrane.
- 九州歯科学会の論文
- 1997-02-25