A Study on Disinfective Efficacy, Side Effect and Toxicity of Formalin-Cresol Mixture

To examine the significance of combined administration of formalin and cresol, antimicrobic efficacy, topical irritability and acute toxicity of FC (formlin: cresol=50%: 50%) were observed, and were compared with those of formalin or cresol administered individually. Obtained results were as follows:1. When formalin was administered with cresol, the disinfective effect of formalin was potentiated, and evaporating capacities of both formalin and cresol and the diffusing capacity of formaldehyde in the fatty subsance were increased remarkably. Accordingly, it is considered that FC is extremely effective for root canal disinfection. In addition, the best ratio between formalin and cresol was turned out to be 50%: 50%, but the ratio 70%: 30% was effective as well.2. While a large part of FC applied in the root canal evaporated rapidly to fill up the sealed cavity, a part of it changed to a kind of resin, which was determined to be the products of acidified polimerization of formaldehyde and cresol. This resin is expected to decrease the topical irritation and to show the disinfective effect less potent but more lasting at the admininistered spot than FC is.3. When formalin was applied with cresol on the rabbit skin, the conspicuous increase ofcapillary permeability to be caused by formalin alone was reduced. The protein coagulability of formlin was increased by combined administration with cresol. It is considered that irritability of formalin combined with cresol can be more restrained and more limited topically than the case of formalin alone.4. The combined adminitration of formalin and cresol showed antagonistic effect in acute toxicity, and LD50 value of FC was higher than those of formalin and cresol.5. To conclude, the combined administration of formalin and cresol has merits of potentiationof the disinfective efficacy: of formalin and alleviation of the side effect and toxicity of it.