An Oral Cleanliness Test Based on Salivary Ammonia Concentrations

Methods: Subjects consisted of 62 office workers, 50 men and 12 women with an average age of 41.4±8.5 years, who consented to participate in the present study while undergoing periodic dental checkup. Subjects were instructed to rest for ten minutes to promote saliva accumulation, and to then expectorate the saliva. The level of salivary ammonia concentration was measured by the indophenol method. And saliva samples were incubated anaerobically for one week at 37°C to determine total salivary viable cell counts, and salivary turbidity was measured at 550 nm. Additionally, standard strains of oral bacteria were incubated anaerobically at 37 ^°C for 48 hours, after which levels of ammonia concentration in the culture medium were measured.

Results: As assessed by logarithmic conversion, salivary ammonia concentration correlated positively with total viable cell count (r=0.81) and turbidity (r=0.72), with statistical significance at p<0.001. Additionally, multiple ammonia-producing oral bacteria species, including Prevotella intermedia, Capnocytophaga gingivalis and Porphyromonas gingivalis were identified in the standard strains.

Conclusions: Many oral bacteria species produce ammonia, and levels of salivary ammonia concentration showed a strong correlation with salivary viable cell counts and turbidity. These findings suggest that salivary ammonia seems to be a useful indicator for oral cleanliness.