片側遊離端義歯においてクラスプのデザインが支台歯の挙動に及ぼす影響
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概要
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This examination was planned to observe the abutement tooth movements of the unilateral distal-extended partial prosthesis with five clasps respectively. The tested clasps were wrought wire clasps of Aker's type (Aw), two types of combination clasps-Aker's type clasps with a wrought wire retentive arm and a reciprocating cast one (Ca), and a combination clasps of Roach's type with a T-bar retentive arm and those of Aker's type with a retentive cast one (Ct)-Krol's RPI retainers (Rk), Kratochvil's I-bar clasps (Ik). The movements of the abutment tooth when crushing the test food of two types-short and long-have been measured by using a displacement sensor in three dimensions. The results may be summarized as follows : 1. As for the inclination of the abutment tooth, the buccolingual inclinations were generally larger than those of the mesiodistal ones significantly (p<0.01), Especially the remarkable inclinations of the abutment tooth were caused when loaded not only on the denture teeth but also on the abutment with the long type of food. 2. As for the twist-like movements of the abutment tooth, not only clock-wise movements but also a counterclock-wise one were observed. When the abutment was also loaded, such movements were reduced a little in Ik, but others tended to be greater in general, especially in Rk remarkably. 3. As for the parallel movement of the long axis of the abutment tooth, the mesiodistal displacements were observed more remarkably than the buccolingual ones generally. The clasp Ct, Ca, and Aw with a distal rest showed greater mesiodistal movements than the clasp Rk and Ik with a mesial rest significantly (p<0.01). On the other hand, buccolingual parallel movements were very small, compared with mesiodistal ones, and little influence was recognized by using either type of food and the various clasp designs. 4. The vertical movements of the abutment tooth increased as loaded not only on the denture teeth but also the abutment itself. 5. The results of this study showed that so-called stress breaking type of clasps caused the tilting action to a distal direction and that the clasps with a distal rest caused greater parallel movements, which should be emphasised rather than the inclinations. The above mentioned results showed a great difference between the ideological clasp theory and the actual movements of the abutment.
- 九州歯科学会の論文
- 1996-06-25