Role of Salivary Duct Morphology in the Etiology of Chronic Obstructive Parotitis: Statistical Analysis of Sialographic Features and Computational Fluid Dynamics Analysis of Salivary Flow

Abstract

The causes of some cases of chronic obstructive parotitis (COP) without obstructive factors are still unclear. The authors hypothesized that some morphologic features of salivary ducts might contribute to the development of COP. This study investigated the role of salivary duct morphology in the etiology of COP. The authors designed and implemented a case-and-control study. Cases were defined as patients with COP, diagnosed from September 2014 to May 2017 at the Affiliated Hospital of Stomatology of the Sun Yat-sen University (Guangzhou, China), and controls were healthy participants. The primary predictor variables were the occurrence of an accessory duct (AD), the number of branches uniting to form the Stensen duct (SD), the angle between the AD and the SD, and the angle between branches identified on sialographic computed tomograms. Data from the 2 groups were compared to investigate the association between these variables and COP. The χ2 test, Student t test, and logistic regression were computed, with significance set at a P value less than .05. Fluid dynamics analysis was used to analyze salivary flow field in models of salivary ducts with different morphologic features reconstructed from sialographic computed tomograms. The sample was composed of 39 patients with COP and 18 controls without COP. The 2 groups were not similar for incidences of an AD (71.8 vs 38.9%) and the angle between branches (96.5±26.0° vs 71.5±21.2°). There was no relevant difference between groups in the number of branches and the angle between the AD and the SD. The area of low velocity was larger in the model with the wider angle between branches. The results suggest that the presence of an AD and a wider angle between duct branches are associated with COP.