舌房縮小が下顎姿勢に及ぼす影響
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概要
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The tongue and the mandible are the organs which function in mutual harmony. Changes in the tongue cause changes in the mandible and vice versa. In clinical orthodontics, restriction of the tongue space often occurs and posture change in the tongue is caused by lingual movement of the anterior teeth, by orthognathic surgery, or by using an orthodontic appliance such as tongue crib. When the harmony between the tongue and mandible is considered, it's conceivable such a change in the tongue posture affects the mandibular posture. The present study, first of its kind, conducts observation of the mandibular position at rest when the anterior portion of the tongue space is restricted and a relative increase in tongue volume, with a resulting change in tongue posture, occur. Ten adult males with normal occlusion and ten adult males with skeletal mandibular protrusion were selected as subjects. Tongue space in each subject was restricted, in stages, by 4 mm at a time up to a maximum of 12 mm by use of a tongue crib. Vertical and horizontal changes in the mandibular position at rest were measured continuously during such restrictions. Tongue pressure was also measured. An apparatus was devised for measuring mandibular movement using a strain gauge and the mandibular position at rest, including the time of no restriction, was measured. Measurements of mandibular position were made every hour for a total of five hours. The results and conclusions were as follows. 1. No differences in changes in tongue pressure and mandibular position resulting from restriction of the tongue space was observed between the normal occlusion group and the skeletal mandibular protrusion group. 2. With increasing restriction of tongue space, the tongue pressure at rest showed a gradual tendency to increase and a significant increase was observed with restriction of 8 mm and over. 3. With increasing restriction of tongue space, freeway space increased and the whole mandible tended to displace anteriorly, and the changes were significant with restriction of 8 mm and over. 4. In the subjects in whom the mandibular position at rest was more anterior than the intercuspal position and the freeway space was more than 1 mm, anterior displacement of the mandibular position at rest, with restriction of tongue space, was more significant (p<0.01) than in the other subjects. 5. The tongue and the mandible were proved to be harmoniously positioned and the mandibular position at rest was proved to be affected by changes in the tongue posture. 6. A relatively large tongue is postulated to force out the mandible in anterior-inferior direction. Therefore, in performing a clinical treatment which involves restriction of the mechanism of the anterior portion of the oral cavity, sufficient care must be taken to allow for changes in the mandibular position at rest.
- 九州歯科学会の論文
- 1982-08-25