Papers by Author: Chae Heon Chung

Abstract: To investigate mechanical fitness of abutment/fixture screw interface in the internal dental implant system, internal connection type implants from AVANA(Osstem®), Bioplant(Cowell-Medi®), Dio(DIO®), Neoplant(Neobiotech®), systems were used in this study. Each group was acquired 2 fixtures at random. Two piece type abutment and one piece type abutment for use with each implant system were acquired. Screw was respectively used to hold a two piece type abutment to a implant fixture. All samples were cross-sectioned with grinder-polisher unit and all specimens were analyzed the interface phenomena between implant fixture/abutment/screw contact interfaces by using field emission scanning electron microscope(FE-SEM). Implant fixture/abutment/screw connection interfaces of internal connection systems made in Korea were in good condition. The results of the above study showed that materials and mechanical properties and quality of milling differed depending on their manufacturing companies.

Abstract: The abutment screw loosening of dental implant system has been remained problem in restorative practices. Surface treatment of screw plays a role of preventing screw from loosening in implant screw mechanism. The purpose of this study was to investigate surface characteristics of ZrN and TiN coated dental gold-screw and Ti-screw by ion-plating method and to evaluate wear resistance, surface roughness, and film adhesion on the screw surface using field emission scanning electron microscopy(FE-SEM), energy dispersive x-ray spectroscopy(EDX), micro-diamond scratch tester, vickers hardness tester, and surface roughness tester. The surface of gold screw and GoldTite is more smoothly than ones of other kinds of non coated screw. The ZrN and TiN coated surface is more smoothly than ones of other kinds of screw. The hardness of TiN and ZrN coated surface showed higher than that of non coated surface. The TiN coated titanium screw and ZrN coated gold screw have a good wear resistance and adhesion on the surface. The surface of ZrN coated screw showed low surface roughness compared with the surface of TiN coated screw.

Abstract: To evaluate the mechanical deformation phenomena of dental abutment screw after tightening and loosening, five species of abutments were selected (3i-three, Avana- two) respectively by two pieces. The abutment screws were repeatedly tightened and removed 20 times with a digital controller. Field emission scanning electron microscope (FE-SEM) was used to observe changes of each part caused by repeatedly tightening and loosening experiment. As the number of tightening and loosening was increased, the wear or distortion of hexed or squared slot that contacted with the driver tip was more severely progressed. Wear or distortion of hexed slot was more severe than that of squared slot and it was more remarkable in the titanium screw than in the gold screw. All the tested screws showed that the width in the crest of their screw thread decreased gradually as the test was proceeded.