By Sarah Guy, MedWire Reporter
A reduction in labial minor salivary gland flow rate indicates the presence of xerostomia more accurately than changes in stimulated whole salivary flow rates, report Japanese researchers.
While both types of salivary measurement were significantly lower in individuals with xerostomia, there was a significantly larger reduction in labial flow rate compared with whole flow rate in those with xerostomia compared with controls.
The researchers used a novel method to measure labial flow in the study, involving placement of an iodine-starch filter paper over an area of the lower lip, which is thought to be able to sample mucosa with both dense and less dense clusters of minor salivary glands, they say.
Indeed, the method identified a highly predictive cutoff value of 0.25 µL/cm2/min for the accurate identification of hyposalivation, the hallmark of xerostomia.
Takashi Sasano and colleagues, from Tohoku University Graduate School of Dentistry in Sendai, compared labial minor salivary gland flow rates and chewing-stimulated whole salivary flow rates in 66 individuals with xerostomia - or self-reported dry mouth - and 30 healthy individuals who acted as controls.
Mean flow rates for both labial minor and whole salivary flow were significantly lower among xerostomia patients, at 0.09 and 0.73 µL/cm2/min, respectively, than control patients, who had corresponding measurements of 0.51 and 2.16 µL/cm2/min.
The researchers also report a positive correlation between both measurements among control participants, but not in xerostomia patients.
The team found that a cutoff of 0.25 µL/cm2/min for labial minor salivary flow measurements gave the highest number of true positive and true negative cases of xerostomia.
Indeed, when compared with the standard whole salivary cutoff of 1.0 mL/min, the labial minor flow cutoff had significantly higher sensitivity (1.00), negative predictive values (1.00), and diagnostic accuracy (0.96) than whole salivary flow rate.
"Using the new iodine-starch filter paper method, we were able to demonstrate a high correlation between labial minor salivary gland flow rate and clinical complaints of oral dryness," conclude Sasano et al in Archives of Oral Biology.
They suggest that the effect of aging on salivary glands should be examined further.
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