DEMINERALIZATION OF HARD TISSUES BY ORGANIC CHELATING AGENTS AT NEUTRAL pH

¹ Division of Dental Research, Faculty of Dentistry, University of Toronto, Canada, and the Department of Applied Materia Medica and Therapeutics, College of Dentistry, University of Illinois, Chicago, Ill.

(1) A new method for demineralizing calcified tissues at neutral pH's is described. The demineralizing agent is an organic chelating agent, ethylenediamine tetracetic acid.

(2) The chemical properties and the experimental findings relative to the use of this agent as a (decalcifying agent are reported.

(3) The acid powder neutralized to a pH of approximately 7.4 by the use of sodium hydroxide, or the sodium salt of ethylenediamine tetracetic acid neutralized to the same pH by hydrochloric acid, in a concentration of 0.5 M., at room temperature, makes a suitable demineralizing medium for small specimens (weighing about 0.5 Gm.) of bone tissue.

(4) The use of higher temperatures greatly increases the speed of demineralization of bone specimens by Edt.

(5) Edt solutions are useful at a neutral pH; hence, they are mild demineralizing agents. This method should prove useful in histologic, histochemical, and chemical studies of bone tissues.

(6) Edt solutions demineralize bone specimens at a rate about one-seventh that of acid solutions and about seven times as rapidly as a neutral decalcifying solution of magnesium citrate.

(7) The mechanism of action of Edt as a demineralizing agent is described.