Comparison of Salivary Inflammatory Mediator Levels Between Four Collection Methods

Objectives: Saliva is being studied as a diagnostic fluid to elucidate biomarkers of oral and systemic disease. While there are numerous collection methods available, few studies have attempted to determine the most optimal technique for salivary biomarker detection. This study aims to compare four salivary collection methods for percent volume recovery, comfort level, and presence of C-reactive protein (CRP), a salivary analyte that is a marker for inflammation. Methods: Saliva samples were obtained from 25 subjects with intraoral inflammatory lesions and 25 age- and gender-matched controls via four collection methods: passive expectoration of unstimulated saliva (PE), stimulated expectoration with 2% citric acid (SE), Salivette® polyester roll device (PR), and Sorbette® polyester sponge device (PS). Salivary CRP detection was determined by ELISA. Descriptive and comparative statistics between collection methods were performed with SPSS 17.0 (Chicago, IL). Differences between collection methods were analyzed with repeated-measures Analysis of Variance with Estimated Marginal Means and the Wilcoxon Signed Rank Test. Results: Compared to PE, percent volume recovery was significantly reduced for PR (72.6±18.5%) and PS (69.9±22.1%); p=.000. Comfort level values (1 to 5 scale) were significantly greater for SE (4.42±0.78) and PE (4.40±0.73) compared to PS (4.17±0.86) and PR (3.96±1.00); p<.01. In subjects with lesions, CRP was detected in more subjects with PE (68%), followed by SE (48%), PR (40%), and then PS (32%). CRP detection was significantly greater with PE compared to all other collection methods (p<.04). In non-lesion subjects, there were no significant differences in CRP detection by collection method. Conclusion: Passive expectoration remains the gold standard compared to the use of collection devices or stimulated expectoration for salivary collection. It is possible that the device material or salivary stimulant may affect or alter CRP detection in saliva. Researchers should consider utilizing passive expectoration when collecting saliva for evaluation of potential biomarkers.