UCSF

BACKGROUND: Sjögren’s syndrome (SS) is a chronic inflammatory autoimmune disease with lymphocytic infiltrate of the salivary and lacrimal glands and reduced salivary flow. Increased incidence of caries and candidiasis, impaired ability to chew and speak, and reduced quality of life are all associated with reduced salivary flow. Although studies show that SS patients tend to have higher caries rates than non-SS patients, less is known about how low vs. high salivary flow rates relate to caries incidence in SS. The purpose of this study was to test the hypothesis that caries incidence is inversely proportional to the rate of salivary flow in patients with SS as well as in otherwise healthy controls.

METHODS: A cross-sectional, prospective study of 30 SS patients and 105 controls was undertaken to evaluate salivary flow rates and caries incidence. Unstimulated whole salivary flow rates (UWS-FR; mL/min) were measured over 5 minutes, and caries incidence was evaluated using the decayed-missing-filled-surfaces (DMFS) index by calibrated clinicians. Mean values, distributions across subjects and teeth, and scatter plots of UWS-FR vs. caries rate for data covariates, such as age, gender, and race, were obtained.

RESULTS: SS subjects exhibited a mean DMFS score of 45 and a mean UWS-FR of 0.113 whereas the controls exhibited a mean DMFS score of 9 and a mean UWS-FR of 0.459. Within the SS group, subjects with low UWS-FR (N= 19; mean; 0.030) had a DMFS score of 51 while those with high UWS-FR (N= 11;mean 0.257) had a DMFS score of 35. Control subjects with low UWS-FR (N = 3; mean 0.070) had a DMFS score of 16 and those with high UWS-FR (N = 102; mean 0.472) had a DMFS score of 8.8. Thus, although low-flow controls had a lower UWS-FR (N = 3; mean 0.070) than high-flow SS patients (N = 11; mean 0.257), low-flow controls still had lower DMFS scores than high-flow SS subjects. Scatter plot data further showed an interaction between age, salivary flow rates, and DMFS scores. In age-matched controls and SS subjects, lower UWS-FR predicted higher DMFS across all decades of life. Notably, this relationship was most pronounced for the 60-69 year olds, followed by the 50-59 year olds, and the 40-49 year olds. In terms of the spatial distribution of DMFS across teeth, in both control and SS subjects there was a lower to higher average DMFS score gradient from anterior to posterior teeth. In the control subjects there were no major discernable differences in the magnitude or pattern of this gradient. In the SS subjects there were higher mean DMFS scores in the low salivary group vs. the high salivary group along the entire anterior to posterior gradient.

CONCLUSIONS: SS subjects exhibited higher levels of DMFS scores compared to controls in relation to UWS-FR levels. The results of this study should be watched closely as age and sample size are major limitations.