THE EFFECT OF MANGANESE AND BORON COMPOUNDS ON THE RAT INCISOR

Abstract

Mn chloride administered subcut. to white rats in dosages greater than 180 mg/kg. produces enamel hypoplasia. The lethal dose of manganese chloride for white rats is approx. 800 mg/kg. The subcutaneous administration of borax and/or boric acid with a total boron content of less than 200 mg/kg. does not cause enamel hypoplasia. The inj. of Mn interrupts amelogenesis in the apical 1/4 of the zone of matrix formation. This is in contrast to hypoplasia produced by Sr which extends over the whole formative zone. Various agents may affect amelo-blasts in different stages of their life cycle.