前歯部架橋義歯に応用される架工歯の力学的研究 : 第1報ロングピン陶歯の三次元光弾性実験

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Generally, the fixed partial prosthesis has been applied by the way of prosthodontic treatment in case of anterior teeth missing, and the porcelain teeth for facing in various ways has frequently been used as the pontic. The pontic of long pin porcelain artificial tooth consists of long pin, porcelain tooth and metal backing. As the bend of metal backing is delivered to pin and make the stress concentration in its tooth, it is expected that its tooth is fructured or came off. Then the long pin porcelain artificial tooth #516, product of S Company, Japan, being enlarge three times of actual size is used for the pontic in this study. As it is expected for the metal backing to be bent by the biting forces and others, the bending load investigations are carried out. What kinds of influence the movement of pin position, i.e., horizontal or long axial movement in incisal side, effect on the stress distribution of its tooth are examined. As regards the photoelastic specimens in this study, the Mizukawa's injection method is applied. The my own load apparatus is designed and made, because the both sides of pontic are connected by the retainer. The two pins are inserted into the specimens, and the four specimens are made in accordance with the movement of pin position. The long axis of crown is devided trisection between base and incisal part on the speciznen, than the line perpendicular to the long axis at the one-third from base part is drawn. The seument of line being caught in the intersecting points between this perpendicular line and crown margin of specimen, is devided equally eight parts. The pin position are symmetrically set at the each three positions of crown long axis, i.e. ; the one-eighth position (1) from the one side of this line, the onefourth (2) and the three-eighth (3). And the each pin is vertically inserted into the lingual face of specimen. By the same method as mentioned above, the each pin is done at onefourth position (4) from crown margin on the line perpendicular to the crown long axis at the onethird from the incisal part. Therefore, the eight specimens are made consisting of two specimens each of four different specimens, i.e., (1) to (4). Then the specimen of position (1) is described as sample A, it of position (2) sample B, it of position (3) sample C and it of position (4) sample D. The load is set up at the central suitable position between two pins and 13 mm from incisal part, and the load direction is arranged at angles of about 120 degree. The load apparatus is arranged in thestress freezing apparatus, product of Riken-keiki Company, Japan ; the stress freeze of specimen is carried out. The slicing directions are parallel to frontal and horizontal plane of specimen. These slices being 2.5 mm thick are kept in the immersed solution between the parallel polarizer in photoelastic apparatus ; the monochromatic fringe method is conducted. As regards the analysis taking account of fringe, the method of Tsuji and others is used. As the results of these efforts, the following conclusion are obtained. 1. As regards the load portion, the stress concentration in specimen are not expressly olcserved. 2. Generally the bending stress in this specimen is few. However, the concentration of stress fringe are located around the pin. 3. As regards the sample D that the pins are inserted into around the load position, it is caused to be bent greatly by pin, therefore ; its stress concentration is higher as compared with the sample B. 4. As the results of investigation for sample A, sample B and C, i.e., the horizontal difference of pin position, the wider th- space between both pins is, the higher the rotation of pin is, therefore ; the stress concentration is increased. But, when the space between both pins is tried to be extremely narrow, the rotation of pin is little, however ; the tensile stress between two pins is higher. 5. Under the influence of force passed through the pin, the specimens are pulled in entirely. The tensile stress in case of sample A is highest, however ; it in case of sample C least.
社団法人日本補綴歯科学会の論文
1971-12-31

前歯部架橋義歯に応用される架工歯の力学的研究 : 第1報ロングピン陶歯の三次元光弾性実験

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前歯部架橋義歯に応用される架工歯の力学的研究 : 第1報 ロングピン陶歯の三次元光弾性実験

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前歯部架橋義歯に応用される架工歯の力学的研究 : 第1報ロングピン陶歯の三次元光弾性実験