Resting and Stimulated Saliva Buffer Test using Handy-type pH Meter

Objectives: To evaluate salivary buffering capacity of resting and stimulated saliva in similar individuals using a handy-type pH meter and to establish a basis for clinical evaluation of resting and stimulated saliva. Materials and method: After collecting resting saliva from 80 patients by direct expectoration, each patient was given a 1-gram piece of unflavored paraffin wax to chew for 5 min to estimate stimulated saliva. After reading the pH value of 0.5 ml of both saliva samples using a handy-type pH meter (Twin pH B-212, Horiba Ltd. Japan), 10ml of 0.1N HCl was titrated into the samples up to a total titration of 160ml, and the pH value read each time. The differences in ranking results (high, medium, low) between resting and stimulated buffer capacity were statistically analyzed by the Kaplan-Meier test (p<0.05). Results: At the point of 50ml titration, the stimulated saliva buffer capacities were ranked into one of the following three categories; high (above pH 5.5), medium (pH from 5.5 to 4.5) and low (below pH 4.5). These pH-ranges were in reasonable agreement with previous saliva buffer capacity reports obtained with both electrometric and colorimetric methods. On the other hand, at the point of 30-40ml titration, the individual resting saliva buffer capacities were ranked into same three categories. Although there were no significant differences in buffer ranking between stimulated saliva and resting saliva with 30ml titration (p>0.05), there was significant difference between stimulated saliva and resting saliva with 40ml titration (p<0.05). Conclusion: Because this quantitative resting and stimulated saliva buffer capacity test can be carried out at the chair-side, it could add important information for clinical caries risk diagnosis. Supported by Grant #14207079 from Japan Society for Promotion of Science and COE Program, FRMDRTB at TMDU.