Purpose: Implant component fractures are one of the most serious complications in implant treatment. With a better understanding of the risk factors for fracture in the preoperative, surgery, superstructure, and post-loading phases of implant treatment, low-risk treatment could reduce implant component fractures, leading to a better prognosis. The aim of this study was to clarify the risk factors for abutment and implant fractures that occur after loading, and to perform a retrospective, approximately 10-year follow-up study to explore the risk factors in each treatment phase. Methods: Subjects were fitted with an implant prosthesis between January 2008 and December 2009. In total, 1,126 Ankylos implants in 430 patients were included for analysis. Binary logistic regression analysis was performed to extract factors related to non-fracture and fracture of the abutment or implant as a dependent variable.

The aim of this study was to show the reaction varieties of human tooth enamel and dentin with a carbonated soft drink, Sprite. After one week exposing into the soft drink, the sliced tooth specimens were examined by macroscopic and microscopic and then carried out the micro X-ray diffraction analysis using a 100 m diameter X-ray beam. The macroscopic and microscopic results showed the wide varieties from the one showing a very slight increase white-spot areas in the enamel to the another showing almost complete decay of the enamel. The crystallites in the examined enamel and dentin changed drastically as follows; the one enamel sample showed the decrease of crystal amount and some ionic substitutions, and the another dentin sample showed the increase in crystallinity and ionic substitutions. These results clearly showed that the original tooth enamel and dentin had their own crystallographic properties differing from each others. This study provided a crystallographic basic data which will be applied to a tayler-made individual preventive dentistry in near future.

The purpose of this study was to evaluate the correlation and distribution of dental postgraduate residents, dentists and clinical training facilities in each prefecture to analyze the regional distribution and supply of dentists in Japan. The results were also compared with referential data for medicine. The coefficient of correlation between the dentist index and dental postgraduate resident index was r = 0.76 (P < 0.001) in 2006. The distribution (coefficient of variation) was greatest for the dental postgraduate resident index. The numbers of dentists per 100,000 population in prefectures with dental colleges were significantly higher in 1986, 1996 and 2006 for each comparison (P < 0.001). Coefficients of correlation between dentist index and dental postgraduate resident index were r = 0.

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Multi-observer assessment involves the assessment of a personʼs work behavior by more than one colleague at the same time for the purpose of human resource development and capacity building. In the medical field, multi-observer assessment is employed to provide formative feedback during regular one-on-one meetings in order to increase the professional competence of medical residents, but it is rarely used in dental medicine. This report describes multi-observer assessment of the performance of trainee dentists at cooperative-type facilities. A total of 70 trainee dentists were assessed in the present study.For method of an investigation, a supervising dentist, a dental hygienist, and a receptionist assessed the professionalism and communication skills of the trainee dentists. There were significant differences of the average scores of assessment about the professionalism of the trainee dentist by all reviewers (p < 0.01, p < 0.05). There was a positive correlation between the average scores assigned by the supervising dentist and the dental hygienist (r = 0.62, p < 0.001,), as well as between the scores assigned by the dentist and receptionist (r = 0.53, p < 0.001,) or the dental hygienist and receptionist (r = 0.78, p < 0.001). These results suggest that there is a strong correlation between assessment by dentists, dental hygienists, and receptionists. The assessment that includes the perspective of the healthcare service recipients (patients) is needed in the future.