Acidogenicity of salivary microflora as an indicator of caries risk

A caries risk test, suitable for mass-screening, should not only be predictive of caries but also be inexpensive, easy to use and provide results in a short time-frame. Therefore we developed a simple colorimetric test (SAP) that indicates the rate of acid production of salivary microbes under acidic conditions.

– assess agreement between the SAP test and levels of salivary MS
– to classify children into caries risk groups using the SAP test
– to assess the risk classification in terms of subsequent caries experience.

Methods: Following addition of saliva to the SAP test solution a change of 0.3 pH units or more over 30 minutes results in a discernable colour change and is classified as high risk, otherwise they are classified as low risk. A sub-sample of n=50 children was used to compare the SAP test against levels of salivary mutans streptocci (MS). The study design was based on a prospective cohort study. Stimulated saliva was collected from n=215 6-8 year old children attending South Australian School Dental Service clinics. Children were classified at baseline into risk status groups and resampled 6 monthly over a two-year period. Caries increment was based on data from routine recall examinations prior to saliva testing and at subsequent follow-up recall examinations.

Results: A comparison of the SAP test to risk status based on levels of salivary MS resulted in a kappa value of 0.66 indicating substantial agreement between the 2 parameters. Of the 215 children followed n=73 had one or more carious lesions over the 2-year period. Assessment of status by risk status showed a sensitivity of 0.219 and a specificity of 0.866.

Conclusion: While the SAP test had adequate specificity the low sensitivity may limit the application of the test as a predictor of caries risk.

Supported by the NHMRC.

N Gully*, D Brennan, A Rogers

Presented at the 84th General Session and Exhibition of the IADR, 28 June – 1 July 2006, Brisbane Australia

Note: * indicates presenter

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