パーシャルデンチャー・デザインが鉤歯の挙動におよぼす影響
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概要
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In order to minimize the damage to the periodontal tissues of the abutment tooth, numerous studies on the abutment tooth behavior with partial prostheses have been undertaken in various ways using strain gauge, photoelastic and finite element methods. However, it was difficult by these methods to detect the three-dimensional dynamic movement of the abutment tooth. The present study examined three-diminsionally the effects of the partial denture clasp assembly and its component parts on the abutment tooth movement utilizing the mandibular kinesiograph (MKG). The mandibular distal-extension removable partial denture was constructed on a simulation model of Kennedy Class II Modification 1. The gingival and alveolar ridge areas and the roots of the abutment teeth were covered with silicone material for simulating the resilient natural mucosa and membrane. Starting from the original denture consisting of denture bases on both sides of the arch and five retainers connected by a lingual plate, the experimental design was altered by reducing the components one after another. The lateral loading to the tooth on the denture caused significantly larger movement of the abutment tooth than the vertical loading. Especially, the inclination of the abutment tooth in the distal direction, which might be the principal factor causing damages to the tooth, was induced by the mesial or buccal loading to the denture tooth. It was also found that the tooth movement was smaller when the load was applied to the second molar of the denture than to the second premolar. The original design of the denture showed the smallest tooth movement in general. There was a tendency that the tooth movement became easy to occur by a smaller load as the components were reduced one after another. However, the design leaving the indirect retainers on the first premolar of the other side of the arch connected by a lingual bar showed smaller tooth movement in the distal direction rather than the original denture. In the unilateral denture with the indirect retainers being removed, on the other hand, extremely larger tooth movement was found to occur. Further reduction in the basal area of the denture base made the denture more unstable, resulting in significantly increased tooth movement. When the applied load was removed, the abutment tooth returned to its original position taking a different route from its inclination pass, occasionally rotating.
- 九州歯科学会の論文
- 1989-12-25