少数歯欠損片側遊離端症例におけるコーヌスクローネ支台の挙動に関する基礎的研究

Abstract

The purposes of this laboratory experiment were to observe the movements of abutment teeth with the Konus-type telescope attachments by utilizing two digital type of laser displacement sensors, and to evaluate their movements through the statistical analysis. Furthermore, another purpose was to examine thoroughly by comparing with the movements of abutment teeth with clasps which had been obtained from the same condition. The results are summerized as follows : 1. On the amount of mesiodistal parallel movements to the long axes of abutment teeth : a) Displacements of design K2 (〓) were significantly greater than those of K1 (〓) and moved towards the mesial direction. b) The amount of displacements when crushing the short type of test food were always four to five times greater than those of when crushing the long type. Little influence of food type, however, could be recognized at 〓 in design K2. 2. On the degree of mesiodistal inclinations of the abutment teeth : Contrary to above mentioned parallel movements, displacements of design K2 (〓) were significantly smaller than those of K1 (〓) and inclined towards the distal direction. 3. On the amount of buccolingual parallel movements to the long axes of abutment teeth, those were the smallest of the whole displacements. In addition, little influence could be recognized concerning amount of loads and food shapes included in K2 (〓). 4. On the degree of buccolingual inclinations : The largest degree of inclination was detected in K1, and it inclined towards the lingual side. 5. On the amount of vertical movements, little difference was recognized between designs K1 and K2 by appearance. but the movement of K2 was greater than that of K1 at highly significant under almost all loads. 6. On the twist-like movements : a) Different directions and amount of the abutment teeth movements were observed due to the food shape. b) Counterclockwise movements were recognized in both designs when crushing the short type of food, and the amount of them increased as loads increases from 3 kg to 7 kg. Clockwise movements arose when crushing the long type of food. Also there was no significant increase in the displacement of the whole abutment teeth. 7. In the displacements in K1, inclinations were occupied about 50%. When connecting the outer crowns to each other (K2), displacements decreased by about 30% and some 34% of the inclinations were also observed in 〓. 8. When comparing the displacements of abutment teeth with these Konus-type retainers to that with clasp accemblies under the same conditions, the degree of inclination in design K1 was almost equal to that in design A. In addition, the degree of inclination in design K2 was almost the same as in designs B, D, and E, but greater than those in designs Aw, Ca, Ct, Rk, and Ik. It may be said in this connection that abbreviated words in the writings represent A : Akers, B : Back-action, Aw : Wrought wire Akers, Ca : Combination with cast and wrought wire Akers, Ct : Combination with T-bar and cast Akers, Rk : Krol's retainer, Ik : Kratochvil's I-bar, and D : Double Akers, E : Extended arm clasp accemblies respectively. The above mentioned results indicate that ideas free from preconceived concepts should be entertained about splinting of abutment teeth. In order to do so, accumulation of still more data about the various cases is necessary.