舌が前歯および歯周組織に及ぼす影響に関する病理組織学的研究

Abstract

It is important for orthodontic diagnosis, treatment and retention to clarify the effects of the oral tissues-mainly the lips, tongue and cheeks-on the positions, angulation and forms of the teeth and the jaw bones. Many of the studies on the force of soft tissues affecting hard tissues have been on "magnitude" and "duration" of the force exerted by the soft tissues would cause in the hard tissues. Fifteen adult dogs were employed for this experiment. Three dogs per group were investigated at 5- 10- 15- and 30 day intervals after appliance setting during the experiment. Tongue force on the lower incisors was eliminated by applying a tongue guard with the lower canines as anchorage, and the changes occuring in the upper and lower incisors and in the periodontal tissues were investigated histopathologically. The results obtained were as follows : 1. Changes occurred in the upper and lower incisors and in the periodontal tissues due to elimination of the tongue force on the lingual side of the lower incisors. 2. By eliminating the tongue force, the lower incisors were caused to move the lingual side because of the lip force. The upper incisors also showed similar changes. 3. Stabilization of bones in the new tissue enviroment was observed btween 15 and 30 days after the appliance setting. Stabilization of the mandible started sooner than maxilla. 4. After stabilization of the alveolar bone, changes to adapt to the structural changes of the alveolar bone took place in the maxilla and mandible. 5. Compared with the changes due to lip-ectomy, the tissue changes due to elimination of the tongue force are milder and stabilization starts sooner. Based on the foregoing, it was ascertained that the tongue plays a very important role in stabilization of the upper and lower incisors and of the periodontal tissues. When the results of lip-ectomy and of this experiment were taken into consideration, it was possible to prove histologically that the upper and lower teeth are stabilized in the positions where the forces of the lips and the tongue are in equilibrium.