Actually, Dr. Stelwagon says tooth paste or tooth powder was "readily eliminated as a factor." He ends up going with lactic acid as a treatment (after trying silver nitrate, Iodine with icthyol, and "salicylated tincture of benzoin and myrrh") and says it kept the crusts from building for several weeks, but wasn't sure if it was a long term cure.
One doctor says his patient was cured with "chlorate of potash" mouthwash. Before you rush to the chemist, this shit is highly flammable and you are likely to spontaneously combust if you try it. :)