Shigaku = Odontology; journal of Nihon Dental College最新文献

In recent, dental implants have been developed and practiced among many dental practitioners depending on the increase of success rate. Also some types of dental implants have been imported from foreign countries in order to obtain more increased masticatory function and esthetics in Japan. On the other hand, some kinds of implant materials such Co-Cr, titanium, ceramics and artificial materials are provided to reconstruct the mandible combined with autogenous bone graft following excision of tumors in the Japanese oral and maxillofacial surgery field. It is my opinion that the success of reconstructive surgery is based on the reconstruction of mandibular bone and the reconstruction of masticatory function by dental implant on the point of oral rehabilitation to reach that the patient should live in comfort. It is well known that not every reconstruction can be satisfactory due to postoperative infection, implanted substances exposed to intra-oral and/or extra-oral sites and/or resorption of the grafted bone under a long term observation. Based on these reasons, we have reconstructed the mandible with revascularized osteomyocutaneous flaps using the microvascular anastomoses technique to reconstruct the defect and to prevent bone resorption. However, even if the reconstruction was achieved successfully, post-operative problems could come into existence due to masticatory, swallowing or speech dysfunctions. These are often caused by loss of soft tissue, deformities of the alveolar ridge or contour of the mandible. Therefore, some kinds of dental implants have been tried in some countries for the reconstruction of the edentulous mandible in order to improve the post-operative functions. The TM-Implant (Transmandibular Implant), which was deviced by Dr. Hans Bosker, Netherland, is one of these dental implants. We tried to apply for two oral cancer cases who had been resected and/or reconstructed mandibles using this implant as the first experience in our country (Fig. 5). The first patient segmentally resected mandible was reconstructed by the revascularized iliac bone, the second patient was marginal resected mandible with tumor (Fig. 6-13). Results of these two implant cases, using TM-Implant, showed significant improvement of oral function thanks of the stability of dentures after the second phase of reconstruction. Dental implants can attribute the functional improvement for oral cancer patients in the future. Strict diagnosis of the bone condition before surgery and careful surgical procedure, whenever dental implants are used, are required to avoid postoperative complications.(ABSTRACT TRUNCATED AT 400 WORDS)

Neher and Sakmann had provided the presence of the channel protein by the direct measurement of single channel current from excitable membrane in 1976. The advantage of this method "patch clamp" is to isolate a small part of membrane and pick up electrical excitability. In order to record single channel current the seal resistance between patch electrode and cell membrane must be at least more than gigaohm. To improve this recording condition enzyme treated cell or culture cell is necessary since fibroblast which attaches to a target cell disturbs gigaseal formation. In this study we use the computer to improve the single channel current recorded by low seal resistance.

The surgical procedure of the implant technique in the private dental office is restricted because of the small number of staff members. All procedures for the implant treatment should be performed with a minimum of staff members: one dentist, a couple of dental hygienists or assistants, with a minimum amount of equipment. Therefore, sufficient conditions for the practicing dentist to perform the implant treatment are summarized as follows: It requires 1) a rather simple operative technique, 2) methods with few special instruments, 3) methods requiring a short operative time, 4) easy reconstruction from mistreated cases, 5) readily available materials, 6) methods applied for all types of tooth deficiency, 7) the material suitable for the aged, 8) stable prognosis. Over several years, using "Bioceram implants" which are manufactured by Kyocera Co., Ltd. (Japan) and by conforming to the conditions as described above, more than 300 cases of the implant treatment have been performed.

Osseointegrated implant was developed by Professor Brånemark at the University of Göteborg, Sweden (1965). Implant are made from pure titanium (Ti 99.75%, others 0.25%), which are installed into the jaw bone using an osseointegrated method by leaving the fixtures unloaded and isolated for a period of 3 to 4 months in lower jaw bone and for a period of 5 to 6 months in upper jaw bone of totally edentuleus patients. The clinical procedure that produces osseointegration is performed in 2 major treatment stage due to being minimized tissue trauma. The fixture are fitted with a series of screw using abutment and prosthetic appliance. Osseointegrated implant placed within the 15 years of the study demonstrated a 91% success in the lower jaw and a 81% success in the upper jaw. We have experienced 30 clinical cases of osseointegrated implant since 1984 and then the clinical use of osseointegrated method give all our patients very satisfactory results. Pre-operative examination (including X-ray findings), surgical technique, clinical cases so on will be reported.

The premotor neurons for the trigeminal motor nucleus were recorded in the supratrigeminal region and parvocellular reticular formation. The responsiveness of these neurons were tested to electrical stimulation of the cortical masticatory area and to natural stimulation applied to the oral-facial area. Fourteen neurons were recorded in the supratrigeminal region and 16 neurons in the reticular formation. A greater number of neurons activated by stimulation of the cortical masticatory area was found in the reticular formation than in the supratrigeminal region. The latency of cortically induced responses of supratrigeminal neurons was longer than that of the neurons of reticular formation. Tactile stimulation of oral-facial area activated 14% of 14 supratrigeminal neurons, which would be including inhibitory relay neurons for the masticatory motoneurons. This result indicate that the many neurons with other functions would be existed in the supratrigeminal region.

Future development in implant prosthodontics should be based on the fundamentals of sound research and reliable clinical implementation. The goals should be to research the safety and efficacy of implants with regard to materials, host receptor site and interfacial zone; to develop acceptable uniform standards of evaluation; and to submit findings to scientific methods of analysis in determining benefit-to-risk factors. This presentation will offer a glimpse at some current developments in basic and clinical research focusing on studies in biocompatibility and host acceptance; the implant-tissue interface; processes in osteogenesis related to vascularization of host sites; and bioengineering studies related to stress analysis and dimensional accuracy of impression systems for implants. The presentation will further describe future directions in research, training and implementation of services through development of an interdisciplinary team. A center is proposed to address the need for combined efforts in clinical++ and basic science research, the broad scope of implant utilization, and the teaching of implant procedures within an academic setting and to our colleagues.

Dental implant has tried at the early stage in 19th century recovering an oral function and esthetics. Technological revolutions in biochemical and new materials have developed on the remarkable change in the dental implants, nowadays we call the three generation therapy for dental implantology. There are many kinds of methods and techniques in dental implants, however a lot of troublesome complication on the process of surgical phase, construction of prothodontics and prognosis of maintenance care. In the proceedings of this symposium, I would like to propose you how to manage the maintenance care for various kind of dental implants through the methodology and case presentations. Tendenay and future for dental implants The current outlook of dental implant has increasing supply and demand not only dentists but also patients. According to Japanese Welfare Ministry's report in 1987, average missing teeth over sixty years old generations are approximately 42% in accordance with NIDR (U.S.A.) research. They are missed on ten over teeth in full 28th teeth dentitions owing to dental caries and periodontal diseases. Generally speaking, latent implant patients are occupied on the same possibility of needs for dental implants both Japan and U.S.A. Management of maintenance care The patients hardly recognized the importance of plaque control for the maintenance care in the intraoral condition after implantation. Dentists and dental staffs must be instruct patients for importance of plaque removal and control, because they already had forgotten the habit of teeth cleaning, especially in the edenturous conditions. 1) Concept of establishment in oral hygiene. Motivation and instruction for patients include very important factors in dental implants as well as in periodontal diseases. Patients who could not achieve on good oral hygiene levels obtained no good results in the long term observations. To establish good oral hygiene are how to control supra plaque surrounding tissues with patient himself. Ultimate concept of implantology have supported common concordance with periodontal therapy. 2) Patients consent and co-operation the right of informed consent, agreement to treatment by the patient has been gaining increased importance to implantology. Even the patient has consent, they must co-operate the process of dental implant with co-therapist (Fig. 2). 3) The clinical examination of clinical parameters in dental implants. (1) Plaque Index (Silness & Loe 1964) and Plaque Control Record (0 Leary 1978) (Table 5). (2) Gingival inflammation (Fig. 3). Ordinarlly, Gingival Bleeding Index (GBI Ainamo & Bay 1975) and Papilla Bleeding Index (Saxer & Jühlemann 1975) are used. (3) The depth of peri-implant sulcus with the plastic probe. (NDU style) (Fig. 4).(ABSTRACT TRUNCATED AT 400 WORDS)

With the life expectancy of our country reaching 80s we are encountering a society with greater proportion of the population in old ages. This social problem creates a relatively important assignment in the area of prosthodontics, especially in full denture prosthodontics. Though the most important factor that affects the success or failure of full denture prosthodontics is the condition of the residual ridge, recent studies have shown that the residual ridges continue to resorb throughout one's life span. Also our survey on the present Japanese denture patients tells us that an average person becomes edentulous at an age of 57.6, has made a full denture twice or more, has worn the denture for 8 to 10 years, and by age 65 to 67 over half of the patients have their mandibular residual ridges being even or the ridge has resorbed extremely so that the ridge is actually lower than the floor of the mouth. With the situation as it is, when we look into the future of the full denture prosthodontics it is inevitable that there will be a rapid increase in patients with extremely resorbed ridges which the present theory of full denture prosthodontics could not handle. In this sense, prosthodontic treatment of edentulous patients with implants is a relatively interesting field. In this article we will comment of the basic application technique and the prosthodontic technique which we have improved of the Brånemark's Osseointegrated implants which possess the long term basic objective clinical data and whose long term safety has been established in edentulous patients. First we will explain the basic application technique using a real case. The patient was a 56 years old female. She came to the clinic with the chief complaint of severe masticatory dysfunction due to unstable full dentures. She strongly desired fixed prosthodontics. She had worn dentures for the past 17 years. The dentures that she had on when she came in for the first visit were her 4th set of dentures. For the past 8 years she had her dentures adjusted and rebased repeatedly. Her maxillary residual ridge had an average height but her mandibular residual ridge was extremely resorbed. EMG examination exhibited conspicuous distortion in chewing rhythm. From the mandibular movement, radiographs of the TMJ regions and the clinical observations it was determined that the vertical dimension had been lost and that her mandible was displaced toward her left and anteriorly. Palpation indicated the condition of muscular tension similar to that of TMJ dysfunction patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Polymorphonuclear leukocytes (PMN) are predominant cells in the gingival crevice and saliva, and may play an important role in oral bacteria. Murine peritoneal PMN was used and stimulated with 9 genera, 17 species of oral bacteria, including cariogenic and periodontal pathogens. The PMN response to the bacteria was measured by the luminol mediated chemiluminescence (CL) response and phagocytic activities, and the activities of lysozyme in the reaction medium after the CL response were also measured. The bacteria which could induce a high level of CL response of PMN were Fusobacterium nucleatum, Treponema denticola and Bacteroides gingivalis; middle grade were Staphylococcus subsp. and Actinomyces subsp.; low levels were Lactobacillus subsp., all 5 species of Streptococci and Enterococcus faecalis. Phagocytic indexes of PMN to various kind of bacteria were distributed from 8 to 40% and the bacterial numbers in 100 PMN were 27 to 301. There was no correlation between CL values and phagocytic indexes or between CL values and the bacterial number in 100 PMN by limiting the data on Staphylococcus, Streptococcus subsp. and Lactobacillus subsp., the correlation efficiency which was obtained between their values was r = 0.91 or 0.86. There was only a little in the lysozyme activities released from PMN by stimulation of various kind of bacteria, and the maximum difference corresponded to only 2.8% of the whole lysozyme activity of PMN. Either catalase activities or SOD activities were measured by H2O2 decomposition or the inhibition of xanthine oxidase activity using the intact bacteria. Neither of the enzyme activities of bacteria were closely related to the level of CL response.

In order to study the clinical significance of ASP and IAP, we have measured serum concentration of ASP and IAP in 259 patients with inflammatory diseases, non-inflammatory diseases, autoimmune diseases and liver diseases. Significantly higher correlation (coefficient of correlation = 0.922) was found between ASP and IAP. There were good correlation between ASP, IAP levels and erythrocyte sedimentation rate (ESR), C-reactive protein (CRP). Coefficient of correlation were 0.705 and 0.673 between ESR and ASP, IAP; 0.621 and 0.623 between CRP and ASP,IAP, respectively. There were food correlations between ASP levels and thrombo test (TT) and hepaplastin test (HPT). The positive rate and mean concentration of ASP, IAP in patients with inflammatory diseases were significantly higher than noninflammatory diseases. It is suggested that serum ASP, IAP could be one of the useful indicator for evaluating the clinical course of patients with inflammatory diseases. Serum concentration of ASP, IAP in patients with chronic liver diseases were lower than normal subjects, especially serum levels in patients with decompensated liver cirrhosis and chronic hepatitis (active) were significantly lower than normal subjects. In patients with hepatoma with cirrhosis, serum levels of ASP, IAP were significantly lower than the hepatoma patients without cirrhosis. The determination of ASP, IAP in liver diseases seems to be useful for evaluating the severity of diseases, the effects of therapy and the forecast of prognosis.