Spatial patterns of dental disease in patients with low salivary flow

Low salivary flow, or hyposalivation, is associated with an increased incidence of dental caries and a shift in their location from biting surfaces towards coronal and root surfaces. However, the relationship between salivary flow and periodontal disease is less clear. To identify clinical indicators of low salivary flow -- including the spatial pattern of dental and periodontal disease, features of the supra- and subgingival microbiota, and symptoms of dry mouth -- we enrolled individuals into two cohorts. The low flow cohort (N = 32) consisted of individuals with a presumptive diagnosis of the autoimmune disorder Sjogrens Syndrome (SS) while the control cohort (N = 119) consisted of healthy controls. We constructed a series of tooth-specific linear models to quantify the extent to which patient cohort, age, and unstimulated whole salivary flow rate (UWS-FR), independent of each other, are associated with dental and periodontal disease at each tooth. While age and a diagnosis of SS correlated with the site-specific increment of disease so too did UWS-FR. Not only were lower UWS-FRs associated with a greater number of decayed, missing, or filled surfaces at 21 teeth, but they were also associated with increased recession, as measured by clinical attachment loss (CAL), at 10 teeth (adjusted p < 0.05). In addition, we examined microbiota community structure at different tooth sites using data from 427 subgingival and supragingival samples of 6 individuals and found that microbial dispersal is reduced in patients with low salivary flow, but only at supragingival and not at subgingival sites. Finally, we found that complaints by subjects of a negative impact on overall quality of life were associated with a UWS-FR less than 0.1 mL/min. Overall, our results suggest that novel predictors of hyposalivation can be identified by integrating clinical, microbial, and patient history data.