Caries begins under a bacterial deposit on the surface of enamel, where decalcification is initiated by acid produced in ensuing fermentation. Each enamel rod is surrounded by a sheath containing organic substance. Fermentation acid (lactic) finds its way to deeper parts of affected enamel, mostly along the sheaths, among which lies the interprismatic substance that connects with enamel cuticle, both of which are keratin-like. Carious enamel shows different zones of demineralization and remineralization. Good keratinizations of enamel cuticle and interprismatic substance, and saliva of optimal qualities, together constitute the best protection against caries.
With acid solutions it was possible, in vitro, to produce initial stages (Caries incipiens) of enamel caries. In a procedure that worked very slowly, for months, enamel organic substance remained undisturbed. By immersing treated teeth for a long period in suitable mineral solutions, remineralization of enamel was effected. The undisturbed organic substance in enamel conducted mineral matter into place. Remineralization of partially decalcified enamel was also accomplished in vivo. Saliva having demineralizing capacity may reverse normal mineralization. Permanent mineralization may be secured only with saliva of optimal quality. [Reported by Rudolf Jeanneret.]
References: Schw. Monat. Zahnh. (with Toyoji Nishimura), 1926; (with Martha Ehrensberger), 1930.