salivary gland hypoplasia salivary gland hypoplasia salivary gland hypoplasia is relative underdevelopment of the salivary glands. salivary gland hypoplasia tends to produce xerostomia (dry mouth), with all the associated problems this brings. it is a rare condition, which may occur as a congenital abnormality or result from lack of neuromuscular stimulation. it may be associated with melkersson–rosenthal syndrome, and hereditary ectodermal dysplasia.