The objective of this study was to identify clinical issues of dental implant treatment over the long term.
The study included 281 titanium screw implants and 90 superstructures that were placed in 66 patients at a single dental clinic in Japan from 1987 to 1992. The cumulative success rate of the embedded implants over a 20- to 25-year period was obtained by life table analysis. In addition, the rates of problem occurrence in the study patients, implants, and superstructures were calculated.
More than half of the patients (n=39) dropped out of the study during the study period. The cumulative success rate for 25 years for the implants was 85.6%. Regarding the region of implant placement, no significant difference in the cumulative success rate was found between the maxilla and the mandible, whereas, concerning the long axis, the cumulative success rate was significantly lower in the implants having a long axis of 7 mm compared to those with a long axis of 10 mm or longer.
During the observation period, the rates of problem occurrence in the implants were 9.6% and 22.7%, respectively for the implants and the patients. On the other hand, the problem occurrence rates of the superstructures were 54.4% and 74.2%, respectively for the superstructures and the patients, during the observation period.
The long-term cumulative success rate of the machined-surface implants was good, whereas many more clinical problems occurred in the superstructures than in the implants. Therefore, it is important to design and produce superstructures that entail less strain of repair or reproduction over a long-term observation period. Additionally, in dental implant treatment in the future, ingenious ways need to be developed to address various challenges due to aging in patients as well as to encourage regular visits for maintenance treatment.

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Introduction: In the procedures for submerged implants (two-stage protocol), the implant body is isolated from the oral environment by the mucoperiosteum during the healing between the stage Ⅰ and stage Ⅱ surgery, and outer stresses and infections cannot easily reach the implant body. Nevertheless, bone resorption occasionally develops around the implant body, and that at stage is defined as early implant marginal bone loss. In this study, to investigate the primary factors considered to be closely related to the prognosis of placed implants, we assessed the following six items: original vertical gap between the alveolar bone level and the implant shoulder, upper and lower jaws, sex, presence/absence of denture, smoking/non-smoking and the presence/absence of gingival tissue exposure.
Subjects and Methods: One hundred sixty-seven patients (62 male and 105 female) were included in this study. Mean age at placement was 58.5, ranging from 15 to 79. Number of implants placed in the upper and lower jaws were 258 and 339, respectively. A spline implant was used in all cases and the placement was carried out by the same surgeon (H.Y.). Four reference points (me-sial, buccal, lingual and distal side) were set around the implants. Each distance between the shoulder of the implant and the edge of the bone crest at both the first placement and stage Ⅱ surgery were measured. The mean value of each subtraction, the former from the latter, was calculated as the amount of early implant marginal bone loss for an individual implant.
Results: Multivariate analysis demonstrated that early implant marginal bone loss was closely related to the following four items in an increasing manner: smoking, denture wearing, original vertical gap between the alveolar bone level and the implant shoulder, and gingival tissue exposure, and a significant difference (p＜0.05) was seen in all of them. No tendency, however, was seen in the position of the upper or lower jaw, or sex.
Conclusion: This study showed that the level of early marginal bone loss was primarily related to gingival tissue exposure.

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Marginal bone level is important for long-term evaluation after implant treatment and it is necessary to know what factors affect the risk of peri-implant bone loss. The aim of this study was to examine the risk factors for peri-implant bone loss around fixed prostheses supported by dental implants regarding marginal bone level changes. The subjects were 501 patients (170 males and 331 females, mean age:56.9 years) who received fixed partial prostheses supported by dental implants and who were examined by routine recall after loading. The average monitoring period after loading was 8.8 years. We measured marginal bone level changes around implants from radiograph images using the Image J software program. We also examined the effect of the factors on periimplant marginal bone loss. The factors included status of remaining teeth and antagonist teeth, implant surface texture, presence of splinting or non-splinting, and location of missing teeth. Statistical analysis was performed using binary logistic regression analysis. The marginal bone loss rate was 13.0% from subject-based data. There was no significant difference in bone loss rate with marginal bone level or location of missing teeth, whereas surface texture, dental antagonist, status of remaining teeth, and prostheses splinting affected bone loss rates.

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This clinical report describes a type 2 DM patient who successfully received full-mouth rehabilitation using dental implants and also experienced improvement of HbA1c with the progress of implant treatment.
A 68-year-old partially edentulous man was referred for dental implant treatment by his physician because he hoped for fixed prostheses. He presented with masticatory malfunction because of tooth mobility and posterior teeth loss. He had 18 remaining teeth, most with untreated severe chronic periodontitis. His past medical history was significant for type 2 DM, angina pectoris, and hypertension.
The patient started to receive oral hygiene instructions and nonsurgical periodontal treatment. Nine teeth were extracted and 12 implants were placed in 3 surgeries so that the patient could eat and maintain a proper esthetic appearance. Caries and endodontic treatments were performed for the residual natural teeth, which received provisional restorations. After detailed adjustment of the full-mouth provisional restorations, they were replaced with definitive restorations. A three-year followup of the case showed functionally and esthetically stable dental implant restorations with no signs of infection or bone loss. The HbA1c level decreased from 7.7% at the first visit to 5.4% after 3 years of definitive restoration delivery, although the patient's diabetes medications remained unchanged during the period.
In the present case, periodontal treatment and improvements in masticatory function associated with implant treatment may have improved glycemic control. However, a large clinical study must be undertaken to clarify the effect of periodontics and/or dental implant treatment on glycemic control.

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The two implant-retained overdenture (IOD) is a costeffective treatment option for the edentulous mandible.In the early days, an unloaded healing period of 3 months was generally advocated. However, due to the inconvenience of this long healing period, the immediately-loaded IOD has recently been trialed. As one of the most important issues with immediate loading is osseointegration failure due to excessive stress on peri-implant bone during the healing period, the use of magnetic attachments has been considered due to their potential to limit hazardous lateral forces. However, literature regarding immediately-loaded magnetic attachment IODs remains limited, at least in Japan. Furthermore, the advantage of immediately-loaded IODs needs to be demonstrated not only by survival rate, but also by patient-reported outcomes such as oral health-related quality of life (OHRQoL) profiles.
The oral health impact profile (OHIP) is a tool for measuring OHRQoL. Recently described OHIP items represent four dimensions of OHRQoL:Pain;Oral Function;Aesthetic;and Social Psychological Impact. It is believed that these dimensions offer a framework to better understand and measure the impact of oral conditions and the effectiveness of dental interventions. This paper introduces a treatment protocol for immediately-loaded mandibular IODs with magnetic attachments, and an evaluation of treatment outcomes using the new OHIP dimensions.
Two patients treated with immediately-loaded IODs with magnetic attachments were selected from patients who visited the Department of Prosthodontics at Showa University. The chief complaint was inability to chew foods due to denture instability. For both patients, surgery to place two interforaminal implants was planned and performed, then magnetic attachments were delivered immediately postoperatively. No complications have been observed in either patient during follow-up.
OHIP questionnaires measuring frequency of impacts experienced during the previous month were administered to each subject after obtaining informed consent, at baseline, 1 month and 1 year postoperatively. The results showed substantial decreases in OHIP summary scores for both patients (66% and 98% decreases, respectively) at 1 year postoperatively. Four-dimensional analysis revealed that the dimension of Oral Function in both patients was both significantly impaired at baseline and significantly improved with immediately-loaded IODs treatment.
Within the limitations of this small case series, immediately-loaded IODs employing magnetic attachments appear to offer effective treatment resulting in an improved functional component of OHRQoL within a one-month period.

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The number of patients who desire oral rehabilitation with dental implants has been increasing due to its improving predictability and an expansion of the indications. Individualized treatment planning is necessary for elderly patients and those who have underlying diseases. In particular, special consideration of the management of intra- and post-operative bleeding is required when placing dental implants in patients with hemorrhagic diathesis. In such cases, implant placement with minimum intervention is required in order to avoid abnormal bleeding.
Dental implant placement with flapless surgery does not need mucoperiosteal flap elevation, thus preventing bleeding, pain and swelling. On the other hand, direct observation of the operative bony site is hindered with flapless surgery, making it difficult to place the implant in the ideal position and direction. A surgical guide plate prepared by computer simulation makes it possible to insert the dental implant in the proper position and direction.
We report here two cases of the successful control of bleeding and infection in patients with hemorrhagic diathesis, who had flapless implants placed using surgical guide plates.

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