New Improved Method for Injection of Acrylic Resin

Abstract

Hitherto, various substances like celluloid-aceton, Wood's metal, Mellot's metal or other low fusible metal were used for injection into vascular system and cavities. With the recent development of high molecular chemistry, acrylic resin is applied in region of anatomy as injection material.
J. K. Narat (1936), W. O. Puckett (1940) and A. A. Liebow (1947) used vinilyte as injection material. This is copolymer of vinyl acetate and vinyl chloride. This is injected in form aceton solution of 10-15%, and left as it is at room temperature for 24-48 hours. The shrinkage after hardening is considerably large, to compensate this, the filler was added.
B. B. Karmrin C. A. Swinyard (1950), Nagata (1950) used dental acrylic resin as injecting material. They used the 'mixture of monomer and pOlYmer in rate of 2: 1 or 4: 1, and the mixture is left as it is until it becomes muddy. In this state, the periphery of individual grain dissolves and presents the homogenious appearance as whole, but the each grain is not dissolved. If such a mixture is injected, some of monomer diffuse or permeate into surrounding tissues. In consequence, perfect polymerization could not be obtained. If such specimens are examined under microscope, individual 'grains are seen in form of chain of beads. Such type of the specimen is not normal, and is dynamically frail. To decrease the shrinkage of vinilyte, Liebow added silica gel or diatomaceous earth as the filler in vinilyte. Upon the plasticity of vinilyte, it surpasses the acrylic resin.
Investigating the question of shrinkage, we co n cluded that is not so serious. By raising the viscidity of monomer and adding 25% of fine grain to it after polymerizing, the shrinkage can be controlled to its minimum extent. In measuring the shrinkage, we found that it is 0.6% in first method, and 0.4 in second method, even on the injected specimen not over 0.8%.