Rejuvenation of brittle gutta-percha cones-A universal technique?

Aged gutta-percha filling cones become brittle and unsuitable for use. Based on a study of the physical properties of the material, a technique was published for reducing their fragility, thus "rejuvenating" them. Replication of this study with seven different cone brands indicated that the technique was successful with only two of the tested brands. A modest improvement was noted in an additional one (30% made usable). The temperature to which the cones were heated had no significant influence on the results but quenching in ice water produced better results than cooling in tap water or in ambient air (p<0.02). These findings indicate that the difference in the composition of various brands of filling cones and the variables in their manufacturing have a great and lasting effect. The technique that has been described for softening brittle gutta-percha points is not universally applicable, but if rejuvenation of the cone is necessary, its effect on a particular batch can be tried.