Latex Cap for Radon Ointment Treatment

Abstract

In the Fall of 1943 the section of Oro-Facial Prosthesis, College of Dentistry, University of California, was asked by Dr. B. V. A. Low-Beer, of the Department of Radiology, University of California Medical School, to solve the problem of fabricating latex caps that would fit over any surface of the body to confine air-tight applications of radon ointment. A technic was developed and latex caps were made to meet the following pre-requisites: (a) Periphery of cap must be in perfect apposition to the tissue, regardless of anatomical contour. (b) There must be no contact between the cap and the lesion proper. (c) The cap must be securely held in place, the periphery sealed air-tight with liquid adhesive instead of adhesive tape. (d) The cap must be light, semiflexible, and sterilizable. (e) The cap must have tissue tolerance. The method previously used was the placement of a piece of rubber dam over the lesion, the periphery being sealed with adhesive tape. The disadvantages of this method were: (a) The frequent inability to seal the periphery airtight. (b) Irritation and annoyance from the use of adhesive tape. (c) Pressure on the lesion. (d) Inability to accurately follow anatomical configuration. To meet the predetermined requirements and avoid the difficulties formerly met, the most obvious approach is to have an accurate impression of the area under consideration. Proceeding with this in mind, the following steps are taken. (a) Place the patient in a comfortable position on a table or a gurney with the area of which the impression is required in a horizontal position. The area of the lesion to be covered by the cap is determined and outlined with indelible pencil by the physician. An accurate impression is taken with a suitable material, such as alginate, colloid, or plaster of paris, and extended at least 1.0 cm. beyond the outline. (b) Pour a positive model from the impression in stone or plaster of paris. This cast with the peripheral margin transferred will be a perfect replica of the area under consideration. The cast, or model, is checked for accuracy, and any irregularities corrected. (Fig. 2.) (c) Modify the model so as to have a space of 3.0 to 8.0 mm. between the finished latex cap and the lesion proper. This is accomplished by carefully placing several sheets of base plate wax over the area to be relieved. (Fig. 3.) (d) Make an impression of this model with the wax onlay as if it were the patient, and pour a new cast. This modified model relieves pressure over the lesion. (e) Adapt base plate wax over the modified model, this time to be the pattern for the latex cap. The thickness of the cap and reinforcement will vary from 2.0 to 8.0 mm., depending upon the size and the shape of the finished prosthesis. Seal the periphery of this wax pattern to the modified model. (Fig. 4, a.) (f) Box in the model with the wax pattern with ash metal or wax and pour a second half in plaster or stone. (Fig. 4, b.)