Authors: Cassidy RE, Gregory WB Jr.
Title: The chilled silver cone as a root canal filling material.
Journal: Oral Surg Oral Med Oral Pathol
Date: Aug 1969
Citation: 28(2):235-42
Category: Obturation
Evidence-based Ranking: 5
Purpose/Objectives: To test, in vitro, the efficiency of using chilled silver cones in prepared canals to improve the root canal seal. Materials & Methods: Forty-two extracted teeth were used in the study. In Part I of the study, the canals of 21 of the teeth were prepared 1 mm through the apex and were divided into three groups according to canal size. A standardized silver point cone at room temperature was fitted into the wet, prepared canal and was adjusted so it was flush with the apex of the tooth when firmly seated. Radiographs were taken from two angles (facial/proximal). The cones were removed, the canals were dried and were then coated with sealer. The silver point and tip of the hemostats were cooled with Freon for 15 seconds. The cooled silver point was then fitted into the canal as far as possible. The cones were not chilled in the control group. The teeth were then placed in 98 degree F water for 48 hours and were then examined for fracture. The distance that the silver point protruded beyond the apex was recorded and the teeth were radiographed. In Part II of the study, the remaining 21 teeth were prepared to “proper” working distance and divided into three groups. Silver points were fitted into the teeth at room temperature, were adjusted to working length and were radiographed. The silver points were then trimmed 0.5 mm from the apical end, were chilled as in Part I and were placed into a canal with sealer. The teeth were then placed in warm water and were radiographed and examined as in Group I. Results: Tables I and II show the values recorded for the lengths. In Group I, all of the chilled cones except one move 0.5 mm or more beyond the apex. None of the control cones moved beyond the apex. In Group II, all but two of the chilled silver cones moved the same distance that they had been shortened. None of the teeth in either group showed signs of fracture. Author’s Conclusion: The authors discuss further studies that should be done with this model before in vivo use, but suggest that trimming silver points 0.5 mm from WL and chilling with Freon may create a better seal of the canal by allowing a larger, chilled silver point to be placed further apically and expand against the dentin wall on warming to body temperature. Validity of Conclusion: Conclusions are valid based on the parameters of the study. Reviewer’s Comments: Interesting paper – concept makes sense and was a good consideration for that time.