Purpose: The purpose of this study was to investigate the efficacy in plaque removal of a newly developed toothbrush, which has a curved handle and long neck. Methods: The subjects included in this study were students at The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan. They were instructed in brushing by the scrubbing method. The test toothbrushes included the following: Toothbrushes A, B and C had flat bristles, while Toothbrushes D, E and F had ripple bristles. In addition, Toothbrushes A and D had a curved handle and long neck, Toothbrushes B and E had a straight handle, and Toothbrushes C and F had a conventional handle. After the subjects brushed their teeth with the test toothbrushes, we examined the efficacy in plaque removal and their acceptance. The efficacy in plaque removal was determined as the percentage (%) reduction of plaque score. Results: The highest reduction of plaque score was Toothbrush A (69.7%). The reduction of plaque score of Toothbrushes D, E, and B were 69.1, 60.3%, and 53.8%, respectively. The results suggested that the curved handle and long neck toothbrush showed better plaque reduction than the others. However, at occlusal surface areas, Toothbrush D showed a higher percentage plaque reduction compared with Toothbrush A. Regarding the questionnaire results, Toothbrush D revealed a higher score of acceptance. Conclusion: The results suggested that the handle and neck length of the toothbrush affected the acceptance in brushing, by improving the ease of using the toothbrush including brushing pressure.

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Objective: CPI is usually employed for mass-screening for periodontal disease. However, as the examination is time-consuming and causes a large burden on the patients, a simpler method of screening for periodontal disease is desired. In this study, we evaluated the effectiveness of a periodontal screening method combining test paper saliva testing and a symptom-oriented questionnaire survey. Materials and Methods: The subjects were 468 adults (362 males and 106 females, with a mean age of 36.6 years) who underwent a group medical examination by their company and consented to the investigation. The samples used for saliva testing were the fluids discharged after rinsing the mouth with distilled water. The items of saliva testing were hemoglobin, protein, white blood cells, and turbidity. Hemoglobin, protein, and white blood cells were examined using test paper and a special reflectometer. The turbidity was determined as the absorbance at 660 nm. The questionnaire consisted of items related to symptoms (12 items), smoking habit, and age. Screening for periodontal disease was performed using CPI, and the subjects were divided into those with and without periodontal pockets. The relationship of each of the saliva testing items with the presence of periodontal pockets was evaluated by the t-test, and items with high sensitivity were selected by calculating the sensitivity and specificity from the ROC curve. Items of symptoms related to the presence of periodontal pockets were selected by the chi-square test. Moreover, the sensitivity and specificity were calculated by combining the results of saliva testing and answers to the questionnaire, and the optimal combination was evaluated. Results: 1. Of the saliva testing items, hemoglobin, protein, white blood cells, and turbidity were all significantly correlated with the presence of periodontal pockets, and hemoglobin showed the highest sensitivity. 2. Concerning symptoms, a high sensitivity was achieved by combining the 5 items of "The gingiva occasionally bleeds during brushing of teeth", "The gingiva is reddened or darkened", "Food is often caught between teeth", "There are loose teeth", and "Have difficulty in biting hard foods". The sensitivity was further enhanced by adding smoking habit and age. 3. Regarding combinations of the results of saliva testing and answers to the questionnaire, the sensitivity was maximized if periodontal disease was considered positive when hemoglobin was positive or when 4 or more of the 5 items of symptoms, smoking habit, and age were positive. Conclusion: A combination of saliva testing using test paper and a questionnaire primarily regarding symptoms was suggested to be useful as a simple method of screening for periodontal disease applicable to industrial dentistry situations.

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Purpose: This study was conducted to determine the influence of light intensity on volumetric shrinkage, and some mechanical properties of a low shrinkage resin composite. Methods: A resin composite which has a ring opening polymerization monomer to reduce polymerization shrinkage, and a resin composite from the same manufacturer were employed in this study. The light intensity of the curing unit was adjusted to 100 and 600 mW/cm². Polymerization shrinkage was determined by using a water-filled dilatometer. SEM observation of cured specimens was conducted. Thermal expansion, filler loading and flexural properties were also measured. Results: The polymerization shrinkage after 180 sec was 1.44-1.59% for DL and 0.84-1.02 for LS. For DL, the volumetric shrinkage began soon after the light irradiation and continued after the end of irradiation. For LS, the volumetric expansion began soon after the light irradiation followed by volumetric shrinkage like DL. The inorganic filler content and the thermal expansion coefficient were 76.8 wt% and 33.3×10^-6/℃ for LS, and 73.9 wt% and 41.2×10^-6/℃ for DL. Flexural strength and elastic modulus were 129.3 MPa and 12.1 GPa for LS, and 130.4 MPa and 10.9 GPa for DL. Various sizes and shapes of filler were observed for LS, whereas spherical fillers of around 2-3 μm were observed for DL. Conclusion: The results of this in vitro study suggest that mechanical properties including volumetric shrinkage of the low shrinkage resin composite might be acceptable for clinical replications. Further studies are required to assess the clinical performance in the oral environment.

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Purpose: In preclinical studies in dogs, the safety and efficacy of pulp regeneration following autologous transplantation of pulp stem cells into the root canal after pulpectomy have been established. However, the challenges for clinical trials of this cell therapy of pulp regeneration are, when the cell processing center is not located in the clinical dental office, to transport the extracted tooth to the cell processing center, and to return the processed cells to the clinical office. Therefore, in this study, the "Principles of clinical studies using human stem cells" were followed, and the standard operation procedure (SOP) for transportation of teeth in less than 12 hours was established to ensure the stable and safe transportation of teeth. Methods: First, the tooth was transported while controlling the temperature using a special container for transport. Optimal transportation solution and antibiotics were selected by the rate of cell survival and adhesion 12 hours after transportation to establish SOP. Furthermore, safety tests for bacteria, fungi, viruses, endotoxins, and mycoplasma were performed in the transportation solution after use, the primary cell culture medium and finally frozen cells at the 7th passage manufactured in an isolator of the cell processing center, confirming the safety of transportation of teeth using this SOP. Results: When Hanks' Balanced Salt Solution containing 20 μg/ml gentamicin and 0.25 μg/ml amphotericin B was used, survival rate was 98%, and cell adhesion rate was high, indicating that it is the optimal solution for transportation of teeth. Using this SOP, although the aerobic bacteria and endotoxins in the tooth transportation solution were slightly higher, finally frozen pulp stem cells were negative in all safety examinations. Conclusion: Thus, it is concluded that teeth can be transported in a safe and stable manner using this standardized method.

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Purpose: Dental students receive basic practice training in order to acquire the necessary techniques as well as clinical knowledge in dental education. This study evaluated the practice tests carried out by the clinicians in charge or the guiding clinical staff who may have different levels of experience in doing these tasks, and so their evaluations may also differ depending on their experience. The objective of the present study was to statistically compare the evaluations by different evaluators. In addition, the evaluation obtained using a laser irradiation marking device was compared with those measured by the evaluators. Materials and Methods: The objects used for evaluation were 108 teeth employed for access preparation by third-year dental students for their practice examination in basic endodontic practice at the Tsurumi University School of Dental Medicine. Six evaluators with different clinical experience participated in this study. Five items were selected for evaluation of access preparation: outline of access cavity, removal of roof of pulp chamber, condition of cavity wall, condition of chamber floor, and presence/absence of perforation. These evaluations were made by both the six evaluators and the laser irradiation marking device and then the results were statistically compared. Results: As for the evaluations, although there was a statistically significant difference between Evaluator C and the other evaluators, no significant difference was observed among the other evaluators. With regard to the agreement for the five evaluation items, there was a low degree of agreement for items 1 through 4, and a higher degree of agreement for item 5. Furthermore, as for item 1, Evaluator C and E showed a statistically significant difference compared with the other evaluators. For item 2, there was a statistically significant difference between the following groups: Evaluator A and C, D, E, F, Evaluator B and C, D, E, F, Evaluator D and E, F and Evaluator E and all other evaluators. For item 3, a significant difference between the following groups was observed: Evaluator A and B, D, Evaluator B and C, E, F, Evaluator C and D and Evaluator D and E, E For item 4, Evaluator D and E showed a statistically significant difference compared with the other evaluators. However, for item 5, there was no statistically significant difference with the other evaluators. Comparing the machine and the evaluators, the five evaluators excluding Evaluator E all showed a significant difference. Conclusion: The results of this study indicated differences in evaluation among the evaluators for most of the evaluation items. Using a number of evaluation items seemed to help achieve a balanced evaluation. Evaluation of endodontic access preparation on artificial teeth using a laser irradiation marking device could be a useful method.

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Purpose: This study investigated the influence of the bonded surface area on the bond strength of bovine enamel and dentin using two-step self-etch adhesives. Methods: Two-step self-etch systems, OptiBond XTR (Kerr, USA) and Clearfil Mega Bond (Kuraray Noritake Dental), were used with a resin composite, Clearfil AP-X (Kuraray Noritake Dental). Bovine mandibular incisors were mounted in self-curing resin and their facial surfaces were wet ground with #600 silicon carbide (SiC) paper. The enamel and dentin surfaces were then treated according to the manufacturer's instructions. Adhesives were applied, and the resin composites were condensed into molds (2.4 or 4.0 mm in internal diameter), placed onto the tooth surface, and then light activated. Ten samples per test group were shear tested at crosshead speeds of 1.0 mm/min. Bond strength values in MPa were calculated from the peak load at failure divided by the specimen surface area. Two-way ANOVA followed by the Tukey HSD test (α=0.05) were done. The treated enamel and dentin surfaces were observed by scanning electron microscopy and the interfaces of resin and enamel, and dentin were also observed. Results: The bond strength ranged from 17.7 to 41.4 MPa in enamel and from 22.0 to 51.4 MPa in dentin. The bond strengths decreased with increasing bonded surface area. There were no significant differences between OptiBond XTR and Clearfil Mega Bond except for the group of 2.4 mm in dentin. From the SEM observations, the etching effect of self-etch primer was more pronounced in Optibond XTR for the treated enamel and dentin surfaces. Conclusion: The results of this study suggest that surface area affects the shear bond strength of two-step self-etch systems.

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