The Action of Enymes on Ethylene Oxide—treated Periodontal Tissue of Rats

¹ University of Kansas City School of Dentistry and Western Reserve University School of Dentistry

An in situ in vitro unit has been devised to study the effects of certain enzymes on collagen of periodontal membrane fibers of rat incisors that had been sterilized in formalin or ethylene oxide. Other investigators have studied enzymatic digestion of collagen following the use of these reagents and have found alterations in the rate of lysis, depending on the amount of tension applied to the fibers.

By means of weights applied to the incisors in situ, the teeth were placed under tention of varying amounts. The units were sterilized with either formalin or ethylene oxide and incubated in cultures of proteolytic organisms or in solutions of pure enzymes (see Tables 1 and 2). A total of 152 experimental and 152 control units has been studied.

No destruction of collagen was evident in experimental or control tissue sterilized in formalin, contrary to other reports.¹⁵ Sterilization with ethylene oxide altered the appearance of the periodontal membrane fibers, but the fibers were not observably altered thereafter by incubation in bacterial cultures. The purified enzymes tested (trypsin 2X, 4X, papain, cathepsin, uricase, and collagenase) caused varying degrees of destruction of the fibrous elements. Uricase was least active.

No alterations were observed that could be attributed directly to tension produced by increasing the weight load. The findings indicate that purified enzymes in sufficient concentration may affect periodontal membrane fibers and that the effect may be modified by fixation of the tissue.