Impact of Loss of Removable Dentures on Oral Health after the Great East Japan Earthquake: A Retrospective Cohort Study

Purpose: The Great East Japan Earthquake in March 2011 destroyed many communities, and as a result many older victims lost their removable dentures. No previous studies have documented the prevalence of denture loss after a natural disaster or examined its negative impact. Therefore, investigation of the consequences of such a disaster on oral health is of major importance from a public health viewpoint. Materials and Methods: Three to five months after the disaster, questionnaire surveys were conducted in two coastal towns, Ogatu and Oshika, located in the area of Ishinomaki city, Miyagi prefecture. Among the survey participants, 715 individuals had used one or more removable dentures before the disaster, and these comprised the population analyzed. The effect of denture loss on oral health-related quality life (OHRQoL) was examined by a modified Poisson regression approach with adjustment for sex, age, subjective household economic status, dental caries, tooth mobility, psychological distress (K6), access to a dental clinic, physical activity, and town of residence. Results: There were 123 (17.2%) participants who had lost their dentures. In comparison with participants who had not lost their dentures, those lacking dentures showed a significantly higher relative risk for eating difficulties (RR = 2.65, 95% CI = 1.90-3.69), speech problems (RR = 4.37, 95% CI = 2.46-7.76), embarrassment upon smiling, laughing, or showing their teeth (RR = 5.32, 95% CI = 2.34-12.1), emotional distress (RR = 2.38, 95% CI = 1.41-4.03), and problems related to social interaction (RR = 6.97, 95% CI = 1.75-27.7). Conclusions: Denture loss appeared to impair eating and speaking ability, thus discouraging communication with others. Public health intervention after major natural disasters should include dental care.