Salivary changes in chronic kidney disease and in patients undergoing hemodialysis: a systematic review and meta-analysis.

Abstract

This study isaimed at describing changes in salivary flow rate and ionic composition present in the saliva of chronic kidney disease (CKD) patients by assessing the pH, calcium, phosphate, and phosphorus concentrations and comparing them to healthy individuals, along with exploring the influence of hemodialysis on these parameters. The bibliographical search was performed in nine databases to find all types of studies, includingobservational clinical studies, without restrictions regarding publication year or language. Two reviewers selected the studies, extracted the data, and assessed the risk of bias using JBI tools. Random-effect meta-analysis was performed with the standardized mean difference (SMD) as effect estimate, at a 95% confidence interval. Thirty-three studies were included in the qualitative synthesis and 31 studies were included in the meta-analysis. Chronic kidney disease patients presented lower salivary flow rate (SMD: -1.73; 95% CI = -2.14; -1.31), higher pH (SMD: 1.57; 95% CI = 1.11; 2.03), and higher phosphorus concentration (SMD: 0.86; 95% CI = 0.63; 1.09) in saliva. Concurrently, salivary flow rate and pH presented significant changes after hemodialysis, with higher salivary flow rate (SMD: 0.53; 95% CI = 0.25; 0.81) and lower pH (SMD: -0.53; 95% CI = -0.88; -0.19) in patients on hemodialysis treatment. Chronic kidney disease patients present reduced salivary flow rate and increased pH and phosphorus concentration in saliva. Hemodialysis can increase the salivary flow rate of these patients.