The chilled silver cone as a root canal filling material

Abstract In an effort to improve the existing silver cone method of filling root canals, we have presented a chilled silver cone technique that relies on the malleability of silver, on silver's contraction and expansion with temperature change, and on the elasticity of dentine. A preliminary in vitro study was conducted on forty-two freshly extracted teeth. In Phase I fitted silver cones were cooled with Freon to a possible -60° C., causing a decrease in cone diameter of at least 0.01 mm. The chilled cones were cemented into canals prepared through the apex. By measuring the distance that the cones moved beyond the apex, we determined that 0.5 mm. was the amount that could be cut off the apical tip of a fitted silver cone and still allow the chilled cone to seat to the original working distance in the sealer-coated canal. Phase II consisted of a practical demonstration of the chilled silver cone technique in conventionally prepared root canals. The silver cones were fitted, and 0.5 mm. was removed from the apical tip of the cones; they were then cooled with Freon and seated to the working distance in the sealer-lined canals. Upon warming to body temperature, the silver cones apparently expanded against the walls of the root canals, probably providing a more adequate seal without causing fracture of the teeth.