局部義歯の維持装置に関する一考察

Abstract

Based on clinical experience over ten years, provision of ridge support for fabrication of removable partial denture was considered to be important for support and stability of the dentures.About 1960, Dr. K.H. Körber improved some disadvantages of the old telescope system and developed so-called Konuskronen telescope. Many clinical results have been reported, since the theoretical background and prognosis of the new device were introduced to Japan.It is without doubt a superb device, however, avthor has experienced some difficulty in it, as follows:1) In the case where anterior teeth are the abutments, those are replaced by full-veneered gold crowns. when the partial denture is removed, anterior gold crowns show. This may cause an esthetic problem, which delicately affects to the patient's psychology.2) Retention of Konuskrone is derived from the forces of friction between inner and outer caps. In this mechanism, very slight space is required between the occlusal surface of an inner cap and the inside of an outer cap. The existence of this space, however, causen such problems as follows:(a) Substance of an outer cap of an abutment tooth at the time when it functions, may loose centric stops.(b) When veneered with resin on the outer cap and if shoulder is made at the cervical part of an inner cap, the retention may be lost due to contact of this part.It is considered, as a counterplan, that the shoulder part of an outer cap should be cut away slightly or an inner cap to be tapered. The former has a demerit in plaue intrusion, while the latter in contour of an outer cap.(c) The support depending merely upon the effect of friction, author feels, show some difficulties in revelation of such grasping force as per an operator intends, and in adjusting at the time supporting force decreases after years later.In order to overcome these disadvantages, author has conceived a new supporting device combining those advantages of the abovementioned device with I.C. attachment. Author has obtained, thereupon, good results in clinical application. Since the device has been newly conceived, author will need time to observe and pursue the prognosis after years.