Clinical Salivary pH Vs. Laboratory Buffering Capacity: A Comparison

Objectives: Measurement of salivary pH chairside can provide useful information to practitioners in managing a patient with high caries risk. Increased salivary buffering capacity has been thought to increase defense against acid attack. The purpose of this pilot study was to determine the association between a chairside salivary pH test and the buffering capacity of stimulated mixed saliva collected at the same visit. Methods: The sample consisted of 15 subjects (53% females, 22-53 years of age) who are enrolled in a caries management study. For each subject, salivary pH was measured chairside and the buffering capacity in the laboratory.  Chairside salivary pH was measured by placing pHion Diagnostic pH Test Strips (pHion Balance, Scottsdale, AZ) in the buccal vestibule for 15 seconds. The color transition of the strips was read as numerical scores in increments of 0.25. At the same appointment, stimulated saliva samples were collected for 5 minutes and transported on ice to the laboratory for determination of buffering capacity. The saliva was diluted four-fold in 0.005N HCl and the final pH determined after ten minutes.  All samples were collected at the same time of the day for each subject. Values were categorized as High or Low, based on enamel demineralization thresholds for both tests. Data was analyzed using Chi-Square statistics. Results: The pH values for the CS ranged from 4.75 to 6.75 while for LS they ranged from 4.0 to 6.10. There is a statistically significant association (p=0.046) between the chairside and the laboratory salivary pH tests used. Conclusions: The chairside salivary pH test used (pHion Diagnostic pH Test Strips) is positively associated with a laboratory salivary buffering capacity test when used as an adjunct tool for caries risk assessment. Supported in part by Oral Biotech.