Tongue-coating as risk indicator for aspiration pneumonia in edentate elderly

Silent aspiration of oral microorganisms is a major cause of aspiration pneumonia. To establish oral hygiene criteria for the prevention of aspiration pneumonia in edentulous elderly persons, we investigated the relationship between presence of tongue-coating and number of oral bacteria in saliva and episodes of pneumonia. A total of 71 edentulous Japanese people aged 65 years or older living in nursing homes were enrolled in the study. A tongue plaque index (TPI) was used to evaluate quantity of tongue-coating, with TPI0 signifying no tongue-coating and TPI1 signifying presence of tongue-coating. Edentate elderly with TPI1 demonstrated significantly higher salivary bacterial counts than those with TPI0 (p < 0.05). The number of elderly patients developing aspiration pneumonia was larger (p < 0.005) in patients with TPI-based poor scores (average TPI > 0.5) than in those with TPI-based good scores. The relative risk of developing pneumonia in the good tongue hygiene group compared with in the poor tongue hygiene group was 0.12, 95% confidence interval (CI): 0.02–0.9. The results demonstrate that tongue-coating is associated with number of viable salivary bacterial cells and development of aspiration pneumonia, suggesting that tongue-coating is a risk indicator of aspiration pneumonia in edentate subjects.