Relationship between tooth loss and tongue pressure and the effectiveness of removable denture for older people requiring long-term care.

Background/purpose: Aspiration pneumonia is a major health concern among older adults, particularly those requiring long-term care. It is often caused by silent aspiration of saliva-containing pathogenic bacteria and exacerbated by impaired oral and swallowing functions. Tongue pressure is a key factor in maintaining these functions, and its decline is associated with increased bacterial amount in the saliva and higher mortality. However, the relationship among tongue pressure, occlusal status, and prosthetic treatment in older individuals requiring care remains unclear. This study aimed to investigate the association between tooth loss and decreased tongue pressure in older individuals requiring long-term care, and to evaluate whether wearing removable dentures can mitigate this decline. Materials and methods: Fifty-three participants (mean age: 82.1 years) from three nursing facilities in Japan were assessed. The collected data included tongue pressure, number of teeth, functional tooth units (FTU), oral hygiene, tongue coating index, xerostomia, and salivary bacterial count. Bacterial counts were measured using real-time PCR. Results: Reduced tongue pressure was significantly correlated with increased bacterial counts in the saliva. Multivariate analysis confirmed the significant relationship between decreased nif-FTU levels and reduced tongue pressure. Although not statistically significant, denture use tended to preserve tongue pressure in patients with reduced natural dentition. Conclusion: Tooth loss may contribute to reduced tongue pressure and increased bacterial amount in the saliva of older adults. Prosthetic treatments, including dentures, may help maintain oral function and reduce the risk of aspiration pneumonia.