Reproducibility of Salivary Parameters

Sialometry and sialochemistry provide a valuable diagnostic and prognostic tool for evaluation and management of salivary gland dysfunction. The reliability of these parameters is essential for their clinical value. Objectives: To examine the intra-subject and inter-subject reliability of salivary parameters. Methods: Stimulated parotid saliva was collected from 40 individuals at 2-min consecutive intervals for a total of 10 minutes. Salivary flow rate and total salivary protein were determined for each 2-min-collection. Salivary flow rate was determined gravimetrically and expressed as ml/min per gland. Total salivary protein was determined using the Bicinchoninic acid method and expressed as mg%. Repeated-Measures ANOVA was used to test for trends over time. Mixed-Effect ANOVA models were used to estimate the variance components for subject, time, and random error. These components were then used to estimate the intra-class correlation coefficients (ICC) as a reliability measure. Results: Saliva collections of 40 individuals were compared in this study (39 female and 1 male), age range (25-72) years (Mean±SD, 52.2 ± 10.2 years). Each individual had five 2-min collections (Table).

Intervals 2-min	Mean flow rate ml/min/gland	+ SEM	Mean total protein mg%	+ SEM
1st	0.34	0.03	125.50	12.30
2nd	0.33	0.03	106.65	16.06
3rd	0.32	0.03	104.91	15.20
4th	0.31	0.02	102.16	12.89
5th	0.31	0.03	104.15	11.09

Statistical analyses indicated that salivary flow rate and total protein values were consistent over time (ICC= 0.82 & 0.87, respectively). The most reliable measurement was obtained between 4-6 minutes (ICC=0.87 & 0.97, respectively). Conclusions: The overall result of this study indicates that salivary parameters are reproducible overtime. Values obtained between 4-6 minutes were reliable and provided adequate representation of salivary parameters. Therefore, for clinical purposes, 5-min collection is reasonably sufficient for evaluation of salivary gland dysfunction.