Gland size estimation and body mass index improve salivary flow rate assessment

Abstract

Although some representative studies, each with over 100 subjects, have reported no significant differences in salivary flow rates between males and females, the majority of such studies have reported that flow rates are significantly higher in males. I am not aware of any studies which have reported higher salivary flow rates in females than in males. It would seem reasonable to expect that large salivary glands would be able to produce higher flow rates than small glands. This could not be tested until a method of estimating salivary gland size was developed. The first such method was described by Ericson and Hedin who showed, in 23 cadavers, a high correlation (r = 0.95) between the parotid gland volume and the area on a lateral sialogram. For the submandibular glands, the correlation was lower (0.68). Ericson then reported, for 92 subjects, a high correlation (r = 0.93) between the logarithm of parotid salivary flow rate in response to gustatory stimulation with 10% citric acid and the logarithm of gland area on a lateral sialogram. In a similar study on submandibular glands but using 6% citric acid in 28 subjects, the correlation coefficient was 0.52. The only study not carried out by Ericson’s group in which a sialographic technique was employed confirmed, in 30 subjects, Ericson’s finding of a positive correlation between the maximum parotid salivary flow rate and the size of the gland. A major disadvantage of the sialographic technique for estimating gland volume is that it gives only a two-dimensional view of the gland. In addition, it is expensive to carry out, it exposes the subject to radiation, and it cannot be employed on all the major salivary glands.