Exploring the relationship of salivary pH and flow rate with tooth wear severity: A cross-sectional study

Background: Tooth wear is the loss of dental hard tissue due to chemical and mechanical processes, and its prevalence ranges from 13 to 80 % in the general population. Management depends on understanding potential risk factors; however, the role of saliva as one of them is not completely understood. The aim of this study was to explore the relationship between salivary pH and flow, and tooth wear in patients referred to a specialized dental clinic for tooth wear management. Methodology: Data used in this study included stimulated (SWS) and unstimulated whole salivary (UWS) pH and flow rate. Dependent variables were the average occlusal Tooth Wear Index (TWI) and the average of the surfaces with the maximum Tooth Wear Evaluation System 2.0 score (TWES). Univariate and multivariate linear regression models were utilized, including a multivariate analysis without outliers. Sex and age were added as confounders. Results: A total of 159 patients were included in this study. The average age of the individuals was 37.1 (+/- 9.1) years and 34 (21 %) were female. Univariate models showed a statistically significant association between both TWI and SWS pH. Multivariate models showed that the negative associations between SWS ((3 = -0.20, C.I. = -0.36 - -0.03 [TWI]; (3 = -0.12, C.I. = -0.22 - -0.02 [TWES]) and UWS pH ((3 = -0.12, C.I. = -0.26 - 0.02 [TWI]; (3 = -0.09, C.I. = -0.18 - 0.00 [TWES]) and tooth wear were largely unaffected by confounders. These associations were also robust against outliers. A relevant association with flow rate was not detected. Conclusion: This study shows that salivary pH was inversely associated with tooth wear severity even after correction for confounders, such as flow rate, age, and sex. This association was especially significant for SWS. Although no causal relationship can be established, the results suggest a role of salivary pH in tooth wear in patients with moderate to severe tooth wear. No association was found between tooth wear and flow rate.