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Impression taking for treatment is indispensable in dental practice. Many types of impression materials have been researched and developed in the past, with the advantages of convenience, high precision, and accurate impression. In recent years, digital imaging devices have become smaller, and their image quality has improved with the development of digital technology. This technology has been applied for development of an intraoral scanner (IOS), which captures the state of the intraoral region in three dimensions. Therefore, optical impressions using IOSs have been attracting attention. The use of IOS is expected to reduce the risk of various errors and infections compared to the use of conventional techniques using alginate and silicone. Furthermore, not using impression materials has many advantages, such as eliminating the risk of aspiration, cost reduction by not using materials such as gypsum, convenience of data exchange due to the use of digital data, and ease of use with dental computer-aided design/computer-aided manufacturing systems. In contrast, the precision and accuracy of IOS are comparable to those of silicone impression material in the posterior segment, but they are inferior in the cross arch. Training for effective use and capital investment is required to use IOSs. Further research on IOSs is warranted as it is a developing technology.

Injectable calcium phosphate cements (CPCs) exhibit many advantages as bone substitution materials. However, the strength of injectable CPCs after setting are often insufficient. In our previous studies, mechano-chemically modification of β-tricalcium phosphate cement powder through a planetary ball-milling process exhibited simultaneous improvement in the strength and injectability of CPC. Two plausible effects of this process are: changes in the CPC powder properties and zirconia abrasion powder contamination from the milling pot and balls. The objective of the present study is to separately evaluate these two effects on the strength and injectability of CPCs. The calculated injectability of the cement paste with and without the addition of zirconia powder were higher than 65% at 6 h after mixing. These values were much higher than that of the CPC paste without mechano-chemically modification, and similar to that of CPC with zirconia abrasion powder contamination. By contrast, the compression strength of the set CPC with zirconia powder additives were higher than that without the addition, and similar to that of CPC with zirconia abrasion powder contamination. These results suggest that the changes in the CPC powder properties due to mechano-chemically modification mainly affected the injectability of the CPC paste, and the zirconia abrasion powder contamination of the CPC powder affected the strength of the set CPC.

Obstructive sleep apnea (OSA) is characterized by intermittent upper airway obstruction during sleep. It causes sleep fragmentation from brief arousal and affects social life by excessive daytime sleepiness. Moreover, OSA is considered a risk factor for cardiovascular complications and type 2 diabetes as associated features. The gold standard treatment for OSA is continuous positive airway pressure during sleep. However, if this treatment is frustrating to the patient or the apnea and hypopnea index is low or mild, alternative treatments for OSA must be found. One possible treatment is an oral appliance (OA) to improve the upper airway configuration. Dental clinicians have attempted to improve this respiratory condition caused by OSA by using OA, and at Tokushima University Hospital, OA therapy has been in use since 1993. Nishigawa et al. introduced a method to fabricate an OA and to investigate the effects of this therapy. In the present article, the method of OA fabrication was modified, and its effects were evaluated. Dental clinicians should have some knowledge about the mechanics of sleep and the management of sleep conditions so that they can cooperate closely with medical physicians. Thus, collaboration between the medical and dental fields can help patients attain healthy sleep.

Background: In the current social scene of Japan, there has been a steady growth of female dentists. Nevertheless, studies that delve into the female Japanese perceptions have been scarce. Objectives: The purpose of this study was to determine the quality of life (QoL) and evaluate the factors affecting job satisfaction of female dentists in Japan. Materials and Methods: Via a researcher-made questionnaire, a cross-sectional survey was done on a total of 156 Japanese female dentists. Results: As per the outcome, 80.8% agreed that they have attained satisfaction with their QoL, while 30.8% strongly agreed. The job satisfaction factors were then listed in descending order of statistical significance as ownership type, having children, pursue PhD, marital status, and annual income. Multivariable logistic regression analysis showed significance in the participants' responses pertaining to ownership type (OR = 2.833, p = 0.013) and the pursuance of a post-graduate course immediately after attaining undergraduate education (OR = 0.425, p = 0.046). Conclusion: Findings suggest that majority of the female dentists in Japan perceive to have attained satisfaction in their QoL. Actual ownership type and immediate pursuance of a post-graduate course were found to be the significant factors related to job satisfaction. This implies that Japanese universities and dental colleges should focus on promoting immediate post-graduate opportunities for female dental graduates.

Background: In 2010, Tokushima University School of Dentistry concluded an academic agreement with Metropolia University of Applied Sciences (Metropolia UAS), which offers degree programs of oral health in Finland. We have collaborated through the student exchange program to foster the knowledge of future global dental hygienists in both schools. In this study, we carried out a survey on the attitude of the dental hygiene students regarding oral health care in facilities for the elderly to develop a new international education program for dental hygiene students. Materials and Methods: The questionnaire on oral health care in facilities for the elderly was given out to the exchange students of Metropolia UAS and students of Tokushima University. Ninety-one (91) dental hygiene students of Metropolia UAS and fifty-six (56) dental hygiene students of Tokushima University participated in this study and statistical analysis were carried out. Results: One hundred forty-seven (147) students from both schools participated in the survey. 80.2% of the students from Metropolia UAS and 69.6% of the students from Tokushima University chose “Moderate” and “Bad” to the questions of “What is your opinion about the current state of oral health care in health care facilities for the elderly?”. There was no statistically significant difference in the answer to the question “Could you work in a health care facility for the elderly as a dental hygienist?” from students of both schools. There was also a statistically significant difference observed by Chi-squared test in the answer of “Do you think that your knowledge of oral health care for the elderly is sufficient?” and the answers of free writing which suggested that Metropolia UAS students have a more positive attitude towards the knowledge of oral health care for the elderly than Tokushima University students. Conclusion: The results of this international questionnaire survey suggested that many students of Metropolia UAS can be considered to have enough knowledge of oral health care for elderly when compared with students of Tokushima University.

Objective: This study aimed to clarify whether crown restorations with adjusted occlusal surfaces that were formed using frontal/lateral mandibular translations, functioned without interference during mastication. Materials and Methods: In 10 adult volunteers who had healthy normal dentition, frontal and lateral border movement was measured during unilateral mastication and free mastication, using an ultrasound digital mandibular measuring system (ARCUS digma2). Additionally, precise impressions of the upper and lower dental arch were taken, and dental casts were made. These casts were measured using a CAD/CAM scanning system (ARCTICA). For the fabrication of crown restorations, the functionally generated path technique (FGP technique) was used on the monitor for the lower first and second molar. The movement of the opposite teeth on the occlusal surface during frontal and lateral border movement, during unilateral mastication, and during free mastication was considered the functional occlusal surface. The data of the functional occlusal surface generated by frontal/lateral mandibular translations and that of each of the masticatory functional occlusal surfaces were superimposed using three-dimensional data evaluation software (GOM). The difference between these surfaces was evaluated to determine the interference area, maximum interference difference, and average interference difference. Results: Interference was present for all functional occlusal surfaces created by mastication as well as those determined by frontal/lateral mandibular translations. The average interference values, in order of free masticatory movement, habitual masticatory side, and non-habitual masticatory side, were as follows. Interference area: 167.5±20.8 mm2, 121.9±28.5 mm2, 144.6±28.0 mm2; maximum interference distance: 345.0±43.1 μm, 189.0±39.9 μm, 309.0 ± 46.8 μm; average interference distance: 130.0±15.7 μm, 64.0±10.6 μm, 130.0±21.9 μm. Statistically significant differences were found for the maximum interference distance and average interference distance (both p

The authors have developed a β-tricalcium-phosphate (β-TCP) powder modified mechano-chemically through the application of a ball-milling process (mβ-TCP). The resulting powder can be used in a calcium-phosphate-cement (CPC). In this study, the effects of the powder-to-liquid ratio (P/L ratio) on the properties of the CPCs were investigated, and an appropriate P/L ratio that would simultaneously improve injectability and strength was clarified. The mβ-TCP cement mixed at a P/L ratio of 2.5 and set in air exhibited sufficient injectability until 20 min after mixing, and strength similar to or higher than that mixed at a P/L ratio of 2.0 and 2.78. Although the mβ-TCP cements set in vivo and in SBF were found to exhibit a lower strength than those set in air, it did have an appropriate setting time and strength for clinical applications. In conclusion, P/L ratio optimization successfully improved the strength of injectable mβ-TCP cement.