Oral Diadochokinesis and Potential Associated Factors in Japanese Older Adult Outpatients

Purpose: This study investigated oral diadochokinesis (ODK) and its associated factors, including age group differences, among Japanese older adult outpatients.
Materials and Methods: A cross-sectional study was conducted with 127 outpatients (≥65 years) receiving dental check-ups (May 2022–February 2023). Oral function was assessed using ODK (pa/ta/ka/) (KENKOU-KUN®), tongue pressure (TPM-01), masticatory performance (gummy jelly), and swallowing function (RSST). Structured interviews measured social engagement (LSNS-16), depression (GDS-15), and cognitive function (MMSE). Statistical analyses included Chi-square tests, t-tests, and linear regression.
Results: Mean ODK values were 6.2 ± 0.7 (/pa/), 6.1 ± 0.8 (/ta/), and 5.6 ± 0.9 (/ka/). Age-grouped differences were found in tongue pressure and ODK /ta/, /ka/. Unadjusted analysis revealed associations between ODK /pa/ and sex, number of remaining teeth, and social engagement. ODK /ta/ was associated with tongue pressure (B: 0.022, 95%CI: 0.008, 0.036), masticatory performance, and swallowing difficulty. ODK /ta/ and /ka/ showed age and sex association. Adjusted regression analysis showed associations between ODK /pa/ and number of remaining teeth (B: 0.028, 95% CI: 0.004, 0.052), ODK /ta/ and tongue pressure (B: 0.021, 95% CI: 0.007, 0.035), masticatory performance (B: 0.095, 95% CI: 0.018, 0.161), and swallowing difficulty (B: –0.679, 95% CI: –1.192, –0.165).
Conclusions: This study reveals ODK’s multifaceted nature, highlighting its relationships with various oral and psychosocial factors. Associations between ODK (pa and ta) and other oral functions suggest that improving ODK could maintain overall oral health and quality of life in older adults. Incorporating ODK assessments into routine dental check-ups should be further assessed. Keywords: ageing, diadochokinesis, oral motor function, orofacial neuromuscular complex, oral hypofunction