Can low dose diagnostic dental radiation trigger Sjögren's syndrome?

Sjögren's syndrome (SS), first described by Swedish ophthalmologist Henrik Sjögren in 1930, is a chronic inflammatory, autoimmune disorder characterized by diminished lacrimal and salivary glands secretion resulting in keratoconjunctivitis sicca and xerostomia. One factor instrumental in severe salivary gland damage and salivary flow decrement is radiation therapy. Apoptosis, implicated in autoimmune diseases, has been shown to be responsible for this damage. However, there are no studies investigating the effect of diagnostic radiation (low dose) on salivary glands. A safe level of radiation has not been established thus far. Diagnostic radiation has been used from 1896, but generally applied only from 1916. Dr. Sjögren identified SS in 1930. It is possible that the introduction of X-rays for diagnostic purposes is associated with SS onset. Available data show drastically reduced use of diagnostic dental radiation in developing countries and a concomitantly drastically reduced or lack of SS in these countries. In countries like India with a population of 1.1 billion (health care level II country), primary SS has been reported to be rare (total of 27 and 23 primary SS and secondary SS patients respectively reported thus far), while a health care level I country like USA, with a population of 300 million, there are about 2-4 million SS patients. Health care level IV countries do not have a single reported case of SS. There is also evidence for ultraviolet radiation inducing subcutaneous lupus erythematosus, an autoimmune disorder. We hypothesize that diagnostic dental radiation could be a factor for the development of SS as a result of either radiation induced apoptosis or through oxidative modification of proteins.