[Dental implants. History and tissue reactions of implants].

Dental implant (oral implant) is totally based on dentistry and the progress in its technology. On this occasion, dental implant are described from the standpoints of experimental pathology and clinical pathology. Demands for improved dental technology have brought significant developments in the dental implant field. Based upon the latest general implant technology, improvements in dental implant technology have primarily taken the form of better materials and designs historically. The object of these developments has been to provide the patients with restored teeth whose structure and function are asymptotically close to those of natural teeth while enhancing recovery of the occlusion function and improving aesthetic quality by means of applying technique of oral surgery (including periodontics) and prosthodontics. The basic structure of the dental implant consists of the substructure buried in the jaw bone, the junction, and the superstructure projected into the oral cavity. These three items correspond respectively to the root, the neck, and the crown of a natural tooth. However, neither the structure nor the function of such an implant body can be identical to those of a natural standing tooth. Physiologic metabolism, which is present in the latter, does not exist in the former. Therefore, it should always be remembered that even modern technology and materials can not reproduce the oral conditions identical to those produced by physiologic tissue and functions which are subject to chronological change. We should bear in mind that this system, unlike those made up by inter-material relations or inter-organic relations is made of an artificial structure, functions apart from the natural organs, and serves only as a substitute. Certain inherently unstable factors are inevitable. For example, radiographic findings confirm that V-shaped radiolucency by bone resorption in the alveolar bone surrounding the tooth neck is always more extensive than in the case of natural teeth. First study: Histopathological Studies of Tissue Reaction for Implant Materials(Fig. 4-10). This study is a basic experiment to help the development of implant materials used in repairing extraction wounds of teeth and bone defects. It is desirable that the materials should be preservable, easy to process, and with high histocompatibility. Examined materials are DCFF or non-DCFF treated bone matrices (grafts) of rats and human, and single crystal ceramics (Al2O3). DCFF treatment is a procedure of decalcifying, defatting and freeze-drying bones and ligaments of animals after fixation in formalin for immunological tolerance (M. KATAGIRI got a patent for this invention in America, West Germany and Japan, Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)