人工歯咬合面形態と義歯の挙動に関する基礎的研究
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概要
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The effects of the occlusal configuration of the artificial molar teeth on the stability of the lower full denture and the load transmitted to the tissue beneath the denture were examined on a simulated model for 0°, 30° and Levin lingual bladed teeth. The occlusal force up to 10kg was applied to three kinds of foods at a speed of 0.2mm/sec with a universal testing machine. The transmitted load and the displacement of the denture was traced using a load sensor and a mandibular tracking device (Saphon visi trainer), respectively. The results obtained were summarized as follows. In clenching without food, no differences could be detected in the behavior of the denture among the teeth employed so long as the occlusal adjustment was properly performed to eliminate any premature contacts and minimize the lateral movements under occlusal loading. All the teeth easily crushed the soft food (boiled fish paste) showing no measurable differences except for the 30° teeth which caused a slightly larger distal displacement of the denture. When the food became a thin layer, the clenching-like behaviors appeared with the food being left on the occlusal plane. In biting the medium soft food (raw potato), the load was once released when the food was broken and then the load increased again to crush the remaining food. Such a phenomenon was clearly observed with the 0° teeth, while the 30° and Levin teeth caused gradual breakdown of the food. The lateral displacement of the denture was the smallest with the Levin teeth. The 0° and 30° teeth, on the other hand, caused a twisting of the denture involving upward displacement of the working side. The characteristics of the teeth were clearly observed in biting the hard and brittle food (pseudofood made of carnauba wax). With the 0° teeth, significantly larger raising of the balancing side of the lower denture appeared and a concentrated load was transmitted to the mucosa on the working side. The load increased by repeating increase and release corresponding to the intermittent fracturing of the food. The lateral displacement of the denture was also marked. The 30° teeth fractured and scattered the food by the smallest level of load, leaving a few or no pieces of the food on the occlusal plane. Although the load transmitted to the mucosa was the smallest, the lateral displacement of the denture was the largest with these teeth. In the case of the Levin teeth, the load once dropped to zero by early partial fracture of the food with their sharp blades soon after the start of occlusal loading and then increased to wholly crush the food in a manner found with the 0° teeth. Consequently the mucosa was subjected to a larger load than that with the 30° teeth, while the lateral displacement was the smallest. It was found from the foregoing results that the effects of the occlusal configuration of the artificial teeth would be more important for harder foods. All the teeth showed individual advantages and disadvantages in their abilities to crush the food and reduce the load transmittance to the tissue for each hardness of the food. In a sense of the stability of the denture, however, the Levin bladed teeth might be superior with which the displacement of the denture could be minimized for all the foods employed.
- 九州歯科学会の論文
- 1993-02-25