Oral infectious diseases, such as dental caries and periodontitis, are caused by oral biofilm, so-called dental plaque. The foundation of the biofilm structure is the extracellular polymeric substances consisting of polysaccharides, toxins, proteins and nucleic acids as well as vesicles, which secrete these components outside of bacterial cells. Among them, extracellular DNA(eDNA) has become increasingly recognized as a key component for biofilm formation and its structural stability. Bacterial histone-like DNA binding protein(HLP), an accessory architectural protein in a variety of bacterial cellular processes due to DNA and mRNA binding capacity, also contributes to the activation of host innate immunity during bacterial infection. Moreover, it has been suggested that vesicles harboring DNA are associated with horizontal gene transfer. In recent two decades, numerous studies regarding the association between oral biofilm infectious diseases and various systemic diseases, such as cardiovascular diseases, atherosclerosis, diabetes mellitus, aspiration pneumonia and autoimmune diseases, have been reported. Besides bacteria, Candida spp., which are frequently implicated in mixed bacterial-fungal infections in humans, can readily form biofilms on the surfaces of denture and cause a variety of infectious diseases ranging from denture stomatitis in denture wearers to life-threatening invasive infections, such as aspiration pneumonia, particularly in immunocompromised and elderly populations. From the viewpoint of biofilm infection, which cause systemic diseases as well as oral infectious diseases, the development of new preventive and therapeutic procedures targeting bacterial-derived pathogenic factors such as eDNA, HLP and vesicle, is expected in future studies.

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Background: During functional loading, the design of the dental implant may have an effect on the response of marginal bone.
Objectives: The purpose of this study was to report the prevalence of peri-implantitis, and to compare radiographic parameters around Brånemark and Replace Select dental implants and evaluate whether disparities in the morphologic features of these two indistinct implant systems, particularly their abutment-implant attachment, had an influence on the health of surrounding tissues and marginal bone loss (MBL).
Materials and Methods: Collection of data was done at the Department of Fixed Prosthodontics, the Department of Maxillo-Facial Prosthodontics, and Oral Implant Center of Tokushima University Hospital, in Tokushima, Japan; between March 2003 and followed until January 2017. Patients who have been treated with the Replace Select internal type implant and the Brånemark variety were selected as cohort. Marginal bone level measurements were evaluated via periapical and panoramic radiographs taken at regular follow-up visit. These dimensions were calculated, starting from the orientation mark at the implant abutment interface to the bottommost perceived contact area of marginal bone with the aforementioned implant system. The change in the level of bone was estimated by calculating the variation involving an initial reference value and the follow-up values.
Results: An average loss of bone at 0.65 ± 1.51 mm (range 0.36 to 7.89 mm) in the Replace Select group was observed, while in the Brånemark group 0.7 ± 1.32 mm (range 0.62 to 8.64 mm) was observed. Spearman rank correlation exhibited a statistically significant positive correlation between progress of bone loss around implant body and interval from implantation in the Brånemark group, whereas in the Replace Select group it was not significant. The Brånemark group exhibited significant (P = 0.0269) negative correlation of MBL and its diameters, whereas the Replace Select group did not exhibit such correlation.
Conclusion: Within the limits of this study, it can be concluded that deviations in the morphologic attributes of these two diverse implant systems had an influence on the health of surrounding tissues and MBL. The Brånemark implants showed a significant increase in MBL (> 1.8mm) as the time of placement elapses. This marked MBL was greater in females than males, in posterior than in anterior, and in the narrow platform implants than the regular platform implants or the wide platform implants. On the other hand, results suggested that this bone loss was greater in the mandible than the maxilla, in single-unit implant crowns than multiple implant restorations in the Replace Select group.

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 Patients with arthrosis of the temporomandibular joint are examined by MRI, but fewer cases are followed over time by performing MRI several times. The objective of this study was to investigate the presence or absence and types of changes in the structure of the mandibular condyle and articular disc on MR images over time in patients examined by MRI for the diagnosis of arthritis of the temporomandibular joint in order to clarify the usefulness of performing MRI several times.
 MR images for patients who underwent MRI several times based on the clinical diagnosis of arthrosis of the temporomandibular joint were analyzed.
 Twenty-three patients were examined by MRI twice or more. The shortest and longest intervals between the first and final examinations were 75 and 2,588 days, respectively, and the mean was 735 days. Changes in the bone structure of the mandibular condyle were noted on the first MRI in approximately 63 % and new changes were noted on the final examination in approximately 24 %. In addition, the articular disc position in the closed or open mouth had changed on the later examination in approximately 15 %.
 Performing MRI several times along the clinical course was found to be useful to diagnose the disease stage, judge the treatment effects, and help predict the outcome in patients with arthrosis of the temporomandibular joint.

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Background: The tongue occupies most of the space in the oral cavity and it plays an important role in oral functions such as mastication, swallowing and articulation. The tongue continues to move from the time of intake to swallowing, particularly during masticating. A method for evaluating tongue thickness at rest by ultrasonography has been proposed; however, the association between tongue thickness and various oral functions remains unclear.
Objective: The purpose of this study was to investigate the relation between tongue thickness and oral functions, and to clarify the clinical significance of tongue thickness measurements in oral function maintenance.
Materials and Methods: Elderly outpatients were serially screened for enrollment and a total of 106 subjects (men, 54; women, 52; mean age, 75.2 ± 6.5 years) were selected. Age, body mass index, and functional teeth number including implant and pontic of fixed partial denture number were recorded as the basic attributes. Tongue thickness, tongue pressure, tongue thrust pressure and tongue motor function were measured as tongue assessments. Cheek pressure, oral moisture and occlusal force were measured as other oral functions.
Results: Subjects with thick tongue tended to have higher BMI, stronger muscle strengths and lower diadochokinesis. Diadochokinesis of /ka/, cheek pressure and functional teeth number were extracted as the independent factors affecting tongue thickness.
Conclusion: Tongue thickness does not necessarily reflect oral functions in healthy elderly people except for a negative association between tongue thickness and oral diadochokinesis of /ka/. Multiple assessments of tongue would be required to evaluate oral function, and the assessment of tongue thickness might have a different clinical meaning.

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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 < 0.05).
Conclusions: The functional occlusal surfaces for each form of mastication demonstrated interference with the functional surface of frontal/lateral mandibular translations. Thus, crown restorations of which the occlusal surfaces were adjusted and formed by frontal/lateral mandibular translations may interfere with mastication.

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Xerostomia, or dry mouth, is mainly caused by systemic disease, biological aging, and drug-induced side effect. The innervations underlying the three major salivary glands and numerous minor salivary glands differ substantially. The trafficking of aquaporin-5 (AQP5), which is specifically expressed in salivary glands, is regulated by the autonomic nerves. Upon the stimulation of the cholinergic nerve, AQP5 travels to apical and lateral plasma membranes, nuclei, and saliva. In this review article, I will describe the subcellular localization of AQP5 in relation to the causes of xerostomia. Ways of managing xerostomia, in particular the use of functional foods and salivary secretagogues, are also discussed.

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Both periapical and panoramic radiographies are routinely used in the daily dental practice. They may accidentally reveal abnormal radiopacities. However, clinicians may overlook or misdiagnose these radiopacities more frequently than abnormal radiolucensies. In this paper, common radiopaque lesions including periapical focal radiopacities and tonsilloliths were introduced. These imaging characteristics and clue to differential diagnosis were also described.

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We report about general anesthesia for disabled patients with special needs or young children during dental treatment in Tokushima University Hospital. We have administered ambulatory anesthesia or general anesthesia with short-term hospitalization for the patients. In this report, we showed anesthesia as a behavior management technique and the system for the patients who schedule ambulatory anesthesia in our hospital. We indicated the present situation of dental treatment under general anesthesia and supposed the prospects of dental care for the patients with special needs.

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A sports-related dental injury is defined as injuries to the oral and maxillofacial regions associated with sports activities, and involves tooth fracture and luxation, facial bone and temporomandibular fractures, and soft tissue injury. Participants in sports activities are always at risk for traumatic injury, with the oral and maxillofacial region often affected. Dental injuries also have a high rate of occurrence among sports-related injuries received during school physical education classes and club activities. Unfortunately, nearly all such dental injuries are irreversible, and the loss of teeth or their supporting tissues has a significant impact on the quality of life of affected individuals. Thus, for prevention of sports-related dental injuries, it is important for dental professionals to disseminate correct knowledge regarding oral health, as well as provide information to reduce and treat risk factors such as dental caries, periodontal disease, and occlusal problems. In particular, use of mouthguard is one of the most effective ways to prevent sports-related dental injuries that occur in sports and physical activity participants. Recently, along with increased health consciousness, the number of individuals who participate in sports and fitness activities is also increasing. Outside of the bounds of conventional dental clinical treatment, dentists are encouraged to actively be involved in local and regional organizations related to sports, recreation, and physical activity opportunities, in order to contribute to promotion of safety and health, including injury prevention. In this review, we discuss various findings to prevention of sports-related dental injuries in children.

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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 Chisquared 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.

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