My husband has no enamel on his teeth due to sjogren's -why is that?

Sjogren's syndrome. Sjogren's chief symptoms are dry mouth and dry eyes. A dry mouth (xerostomia) is an ideal environment for the build-up of plaque and the growth of bacteria that causes tooth decay. If not treated early, the decay can advance rapidly, destroying enamel, and is often non-repairable.
No saliva. Sjogrens is a difficult condition that decreases the body's ability to ake saliva (spit). Saliva is critical for proper digestion and oral health. It's absence causes many problems including loss of tooth enamel.