The genu of the submandibular duct--is the angle significant in salivary gland disease?

OBJECTIVES: To investigate whether the angle of the genu of the submandibular duct is a significant contributory factor in the development of salivary calculi or sialoadenitis.
METHODS: A preliminary test with a phantom was performed, taking oblique lateral views with different vertical and horizontal beam angulations to assess the effect on the genu angle. The phantom comprised a dried mandible and a piece of wire bent to simulate the submandibular duct. There were no differences in the measured angle of the bend in the wire within the range of beam angulations used in the clinical study. One hundred and two sialographs were analysed from three separate groups of patients, normal controls (n=18), proven salivary calculi (n=61) and those with sialoadenitis (n=23). The oblique lateral radiographs were digitised and imported into the Denoptix digital system, and the angle measured using the VixWin 2000 software. Differences in angle between groups were investigated using analysis of variance.
RESULTS: The mean angle of the genu was 103 degrees (range 41 degrees-147 degrees) in the control group, 108 degrees (range 46 degrees-178 degrees) salivary calculi group, and 91 degrees (range 24 degrees-155 degrees) in sialoadenitis patients. There were no statistical differences in the angle between the groups.
CONCLUSIONS: There is a wide variation in the angle of the genu of the submandibular duct (24 degrees -178 degrees ). This angle does not appear to be associated with either sialolithiasis or sialoadenitis.