Saliva Sampling Methods Validation for a Mutans Streptococci Test

Objectives: The aim of the present study was to validate different saliva sampling methods for the inoculation of the CRT bacteria test, using the laboratory microbiological mutans streptococci assessment, as the golden standard method.

Methods: The study population consisted of 36 children, 7 to 10 years old. Four CRT bacteria tests (Ivoclar- Vivadent) were used per person, to estimate the number of mutans streptococci in saliva and were inoculated either by stimulated saliva as recommended by the manufacturer or by unstimulated saliva. Stimulated saliva was collected to be used both for the CRT test inoculation and for the estimation of the mutans streptococci levels in the laboratory after further processing. Mutans streptococci levels were assessed from the MSB agar, based on colony morphology. Unstimulated saliva was collected using a) a plastic pipette, b) a sterile wooden spatula and c) a sterile piece of filter paper wetted on the buccal mucosa. All sampling methods were then validated using the laboratory mutans streptococci assessment method as the golden standard, by calculating sensitivity and specificity. Spearmanxs correlation coefficient was used for comparisons among the sampling methods.

Results: The highest sensitivity of the CRT test 84.62 was found when stimulated saliva was used, while the second best, 46.15 was found for the unstimulated saliva collected via a plastic pipette. Specificity was always higher than sensitivity, for all methods tested. Comparison among the sampling methods showed significant correlation between the stimulated saliva method and: pipette r=0.64, spatula r=0.55 and filter paper r=0.57.

Conclusions: Stimulated saliva used to inoculate the commercial CRT bacterial test yielded the highest sensitivity compared to the alternative sampling methods with unstimulated saliva.

This study was partially supported by Ivoclar-Vivadent Co.