The need for domiciliary dental care has increased with the aging of Japanese society. The Tokyo Metropolitan Government and Tokyo Dental Association conducted a survey of dental institutions within Tokyo in order to clarify which factors influenced implementation of domiciliary dental care by dental institutions. The proportion was significantly higher in (1) dentists in their 50s or older, (2) those working in cooperation with primary care physicians, (3) those providing dysphagia rehabilitation, (4) those who give information on prevention of aspiration pneumonia, (5) those who attended training on medical or domiciliary dental care for the elderly in need of nursing care, and (6) those who attended training workshops and seminars provided by the Tokyo Dental Association in 2010. In the logistic regression analysis, a significant odds ratio was obtained for the same items, excluding age. Attendance at training on medical or domiciliary dental care for the elderly in need of nursing care had the highest odds ratio. Those who attended any kind of training course implemented domiciliary dental care significantly more often. Training conducted by the Tokyo Metropolitan Center for Oral Health of Persons with Disabilities, Tokyo Dental Association, and local dental associations showed a significant odds ratio, with the highest by the Tokyo Dental Association. Traditionally, education on domiciliary dental care in the elderly is not provided at the college level. The present results indicate the importance of educating students with regard to the unique challenges such work poses. Attending seminars hosted by the Tokyo Dental Association also significantly influenced implementation of domiciliary dental care. This seems to be an important result, suggesting the effectiveness of training provided by dental associations with regard to the promotion of domiciliary dental care. This indicates the need for dental associations to provide such training throughout Japan.

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The purpose of the present study was to investigate the relationship between mastication and head posture using foods with different degrees of hardness. A total of 12 healthy, dentulous volunteers participated in the study. Each participant was required to chew two types of gummy candy with two levels of hardness while sitting upright. Measurements were conducted using an optoelectric jaw-tracking system with 6 degrees of freedom (Gnatho-Hexagraph II JM-2000®). The horizontal plane perpendicular to the direction of gravitational force served as the reference plane. Analysis of the gradient of the Frankfurt plane (head posture) and pitching of the head during masticatory movement was conducted. The influence of the type of test food on these parameters was evaluated during mastication. During stable mastication, the gradient of the Frankfurt plane was 4.66 degrees on average, close to the horizontal plane. The time course of the Frankfurt plane gradient revealed a tendency toward dorsal flexion during the first to middle phases of mastication, and a tendency toward ventral flexion during the middle to last phases, regardless of the hardness of the test food. The participants were divided into two groups based on change in head posture during chewing. The results showed while there was no change in head posture in the group with marked pitching of the head, head posture did change in the group with little pitching.

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The purpose of this study was to clarify the viability of a novel method for removing debris from broken instruments from root canals using a laser apparatus. Laser welding was performed on stainless steel or nickel titanium files using an Nd:YAG laser. Retention force between the files and extractors was measured. Increase in temperature on the root surface during laser irradiation was recorded and the irradiated areas evaluated with a scanning electron microscope. Retention force on stainless steel was significantly greater than that on nickel titanium. The maximum temperature increase was 4.1°C. The temperature increase on the root surface was greater in the vicinity of the welded area than that at the apical area. Scanning electron microscopy revealed that the files and extractors were welded together. These results indicate that the laser welding method is effective in removing debris from broken instruments from root canals.

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The purpose of this study was to provide the estimated percentile curves of occlusal pairs (OPs) in adults for use in oral health instruction. Data on number of present teeth (PT) were obtained from the National Report on the Survey of Dental Disease in 2005. Data from 1,535 males and 2,248 females, ranging in age from 18 to 82, were analysed. The mean number of OPs were used from our previous report. In that report we can be estimated OPs from the number of PT. In this study, PT data were replaced by the mean number of OPs. Estimated percentile curves in males, the 10th percentile of OPs was 13.7 at 60 years of age and 12.5 at 70. The 50th percentile of OPs was 12.2 at 50 years of age, 11.2 at 60 and 5.4 at 70. The 90th percentile of OPs was 7.6 at 50 years of age, 2.1 at 60 and 0 at 70. There appeared to be a cut off point after 10 OPs where the 50th to 97th percentile curves of OPs dropped off rapidly. In females, the 10th percentile of OPs was 13.4 at 60 years of age and 12.7 at 70. The 50th percentile of OPs was 11.5 at 50 years of age, 10.2 at 60 and 6.2 at 70. The 90th percentile of OPs was 7.1 at 50 years of age, 2.4 at 60 and 0 at 70. In females again the percentile curves dropped off after 10 OPs. Our results suggest that the loss of OPs may be accelerated when the number of OPs drops below 10. This means that patients need at least 10 OPs in order to maintain a stable oral status. The estimated percentile curves given in this study should be made available for use in adult oral health education.

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The aim of the present study was to examine the adsorption of bovine serum albumin (BSA) to hydroxyapatite surfaces by means of zeta potential. The electrophoretic mobility of both hydroxyapatite and BSA were negative, with BSA itself less negative than hydroxyapatite. The zeta potential of the surface of BSA-adsorbed hydroxyapatite was significantly more negative than that of hydroxyapatite alone (p<0.0001). The BSA histogram indicated two negative peaks, and the zeta potential of BSA-adsorbed hydroxyapatite also showed two similar negative peaks. These results suggest that BSA adsorption to hydroxyapatite surfaces is related to electrostatic interaction.

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Dens invaginatus is a morphological abnormality of the tooth in which the coronal tooth enamel and dentin fold inwards towards the pulp cavity. Dens invaginatus type III (Oehlers: 1957) is characterized by infolding of the enamel and dentin as far as the root apex. This report describes a case of surgical and non-surgical endodontic therapy for a maxillary lateral incisor with type III dens invaginatus, necrotic pulp, and an associated large periradicular lesion. The patient was a 16-year-old man. Periapical radiographs suggested the presence of an untreated area of invagination. Cone beam computed tomography (CBCT) was then used for three-dimensional observation of the morphological details of this area. The CBCT scans revealed invagination and its relationship with the pulp chamber. A dental operating microscope was used to access two primary root canals and the area of invagination. The root canals were then localized, negotiated, enlarged, and filled with calcium hydroxide. Two months later, the canal and invagination were obturated with core-based gutta-percha (FlexPoint Neo: FP core-carrier technique) and restored. Cone beam computed tomography and microscopic techniques allow even complicated cases of dens invaginatus to be diagnosed and treated using non-surgical root canal management.

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The aim of this study was to investigate the effects of swallowing exercises on oral function in independent elderly patients visiting the Department of Prosthodontics at Tokyo Dental College Chiba Hospital. Twenty-nine patients aged over 65 years (15 men and 14 women; mean age, 75.0 years) in whom treatment was completed at this college were enrolled in the study. The patients were instructed on how to perform swallowing exercises monthly (including at baseline) for the first 2 months from the start of the study and asked to perform those exercises at least once daily. At the beginning and end of the study (a 3-month study period), the Repetitive Saliva Swallowing Test was conducted and occlusal force, oral diadochokinesis, unstimulated whole saliva flow rate, stimulated whole saliva flow rate, salivary pH at rest, and salivary buffering capacity measured to determine the effects of the exercises on oral function. Analyses demonstrated significant increases in diadochokinesis rate (/ta/ and /ka/) and unstimulated whole saliva flow rate (p<0.05), suggesting that the swallowing exercises promote the maintenance and improvement of oral function in the independent elderly.

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Bisphosphonate-related osteonecrosis of the jaw (BRONJ) affects quality of life and is an important problem for dentists. A Japanese position paper on BRONJ was published in 2010. The purpose of this study was to review clinical data on the treatment of BRONJ obtained at the Clinic of Oral and Maxillofacial Surgery, Tokyo Dental College, Chiba Hospital to further our understanding of this disease. A total of 13 patients (6 men and 7 women) were included. All the patients included in this study had received Bisphosphonate (BP) therapy and had BRONJ. Five of them (38.5%) had received oral BP therapy for osteoporosis, while the remaining 8 (61.5%) had received parenteral BP therapy for bone metastases from breast or prostate cancer. Osteoporosis patients were treated with risedronate or alendronate. Breast or prostate cancer patients were treated with zoledronate. Two patients with rheumatoid arthritis were treated with corticosteroid. Three patients had diabetes mellitus. Eleven patients were treated with antibiotics, while 5 underwent surgical treatment. Discontinuation of BP was recorded in 7 patients during dental treatment. Sequestration was observed in 6 patients during an 11-month follow-up. Eventually, healing and improvement of the oral mucosa were observed in 3 patients. The current standard treatment for BRONJ does not always provide good results. It is necessary to accumulate further clinical data to establish more effective treatment strategies for BRONJ.

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