Although osteopontin (OPN) is a bone-matrix protein regulating bone metabolism, recent findings demonstrate that OPN also has various roles in inflammation and metabolic diseases, and that the plasma OPN levels are high in patients with diabetes. Diabetes patients are known to have a tendency to suffer from severe periodontitis. However, the definite factors influencing the severity of diabetic periodontitis have not yet been identified. The aim of this study was to investigate the association of OPN with the severity of diabetic periodontitis. Using a rat model of obesity-related type 2 diabetes, experimental periodontitis was induced by placing a ligature around an upper molar tooth. On days 3 and 20 after the ligature, the alveolar bone height and OPN localization in the periodontal tissues were investigated by micro-CT analysis and immunohistochemical staining, respectively. Micro-CT analysis revealed that the 20-day ligature treatment induced more severe bone resorption in the diabetic rats, with 1.3-fold more bone resorption, than in the control rats. Immunohistochemical staining of the gingival connective tissue on day 20 revealed marked OPN localization at the ligature site in the diabetic rats, whereas only mild staining at the site was observed in the control rats. These results indicate that this experimental system is useful for the study of diabetic periodontitis and the possible association of OPN with the severity of diabetic periodontitis.

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Sonic toothbrushes have become increasingly popular in recent years and are believed to have the advantage of a high plaque removal efficacy. Based on this, they are thought to have an effect on the bacterial flora in the periodontal pockets. However, only a few studies have reported the effect of brushing with a sonic toothbrush on the bacterial flora in the periodontal pockets. In this study, we evaluated the effect of brushing with a sonic toothbrush on plaque removal, in addition to its effects on the clinical parameters; furthermore, its effect on the bacterial flora in the periodontal pockets was also evaluated. Sonic toothbrushes operating at three different frequencies or a manual toothbrush were randomly distributed to 40 subjects. The following clinical parameters were assessed: probing pocket depth, gingival bleeding index, and gingival index. O'Leary's plaque control record (PCR) was used to record the degree of control of the dental plaques. The improvement rate was measured by the entries in the plaque control record made at the baseline, and at 2 weeks and 4 weeks after the start of use of the assigned tooth brush. Bacterial flora were analyzed using the polymerase chain reaction invader assay. Trends towards improvement of the PCR and clinical parameters were recognized between the baseline and the end of 4 weeks in all the groups, with no differences, however, observed among the groups. In addition, no differences were recognized in the number of bacteria in the periodontal pockets. These results suggest that proper use of a toothbrush results in considerable plaque reduction and improvement of the clinical parameters, irrespective of the type of toothbrush used. Furthermore, use of a sonic toothbrush had no effect on the bacterial flora in the periodontal pockets at the end of 4 weeks of use.

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Hemisection is thought to be among the most common of dental treatments provided by a dental trainee. This study was aimed at investigating the effectiveness of an audio-visual aid for basic training of dental trainees in manual skills related to hemisection on a simulated model. Materials & Methods: A total of 16 dental trainees in year 2013 in the Department of Comprehensive Dentistry and Clinical Education, Nihon University School of Dentistry Dental Hospital, were divided into two groups: a non-experienced group, consisting of 8 trainees who had no previous history of clinical visit or the dental auxiliary of hemisection, and an experienced group, consisting of 8 trainees with a previous history of having performed clinical visit or the dental auxiliary of hemisection under the guidance of instructing dentists. All the subjects were examined by a pre-test before the basic training on a simulated model. After viewing hemisection in a periodontal basic training video under the supervision of created by The Japanese Society of Periodontology, basic training on hemisection on a simulated model was carried out for the dental trainees. The basic training on the simulated model was evaluated using an evaluation sheet, and a post-test was carried out after the basic training. Results: There were no statistically significant differences in either the pre-test scores or the post-test scores between the two groups. Both groups received a high score on the evaluation sheet, however, there was no statistically significant difference in the score between the both groups. The post-test score was statistically significantly higher (p<0.01) than the pre-test in both groups Conclusion: Our results suggest that use of an audio-visual aid is useful for training dental trainees in hemisection.

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