Preventive Dentistry
Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences
Research background and outline
Several epidemiological studies on oral diseases, including intervention studies, have been conducted on a school-wide basis to prevent caries since 1970. These studies have achieved positive results in model areas by increasing the rate of caries-free children aged 11-12 years to 90% and reducing the average number of carious teeth to 0.1. Data, along with laboratory studies on oral bacteria, were collected and analyzed to identify the cause of dental caries in children at high risk in whom caries development could not be prevented by the basic caries prevention program.
The World Health Organization (WHO) Oral Health Country/Area Profile Program has been revealing the epidemiological characteristics of periodontal disease in different nations since 1989. Based on the concept of periodontal health derived from the Global Network study, new methods for screening and monitoring periodontal diseases need to be developed. Furthermore, the WHO Global InfoBase needs to be developed by collecting the basic data necessary for health policy planning.
Previous epidemiological studies have revealed that halitosis, which attracts public attention, is often caused by mouth problems. Focusing on the fact that volatile sulfur compounds are the causative agents of true halitosis associated with periodontal disease, we evaluated the pathological condition of periodontal disease by measuring the volatile sulfur compound level and performing an epidemiological study to predict periodontal disease progression.
The Niigata Elderly Study, a longitudinal study conducted since 1998, has investigated the relationships between oral and general health and disease development and progression. Additionally, more than 150 research papers have been published.
Furthermore, we conducted international joint research with the University of Michigan in the United States (periodontal and systemic diseases), Newcastle University and Queen's University Belfast in the United Kingdom (oral health and nutrition), and King's College London (oral cancer and precancerous lesion) in the United Kingdom. Additionally, we conducted basic epidemiological studies on the relationship between the development of oral disease and lifestyle in collaboration with dental schools and health ministries in Myanmar, Thailand, and Indonesia to develop an oral health policy. These studies are part of the activities of the WHO Collaborating Centre for Translation of Oral Health Science (JPN-75).
We conducted clinical intervention studies in collaboration with the Department of Internal Medicine to investigate the effects of periodontal treatment using antimicrobials on the improvement of insulin resistance in patients with diabetes and confirmed a significant increase in serum adiponectin concentrations.
We developed a simple gas chromatograph specifically designed for the halitosis test. The effectiveness of this device was confirmed by our clinical studies. Currently, simple gas chromatographs are available on the dental market worldwide due to their convenience for chairside use in private practices. Additionally, oral rinses and sprays containing zinc chloride have been found to be effective in treating halitosis in cross-matching. Clinical studies have shown that plant-origin proteases are effective in controlling tongue coat, thereby preventing halitosis. Further clinical studies using proteases with different profiles are needed to introduce proteases into the nursing-care scene for older adults.
In preventive dentistry, individual health management plays an important role in caries prevention in children, root caries prevention in older adults, and periodontal disease prevention in adults. Therefore, developing programs for the assessment, prediction, and maintenance of disease risk are major themes for future studies. We need to collect further clinical data to achieve these goals.
We are conducting basic research to develop a caries activity test that focuses on the glucan-synthesizing ability of Streptococcus mutans, a common cariogenic bacterium. The glucan-synthesizing ability has been confirmed to vary depending on the strain. Thus, assessing the insoluble glucan-synthesizing ability of S. mutans in the mouth is more effective than the conventional caries activity test in screening children at a high risk of caries whose caries cannot be prevented by basic caries prevention programs. We are currently analyzing the gtfB gene coding for the insoluble glucan synthesis of S. mutans to investigate the insoluble glucan-synthesizing ability corresponding to the base sequences in different strains.
Research themes