A comparison of the marginal leakage of retrograde techniques

An investigation of the apical seal of the most popular retrograde techniques was attempted. Ninety extracted maxillary central incisors were instrumented and obturated, and various apical procedures were performed. The depth of penetration of 2 percent methylene blue dye was used to evaluate the apical seal. Retrograde amalgam, heat-sealed gutta-percha, and the apicoectomy control showed average depths of penetration of 3.1, 4.0, and 4.6 mm., respectively, while cold-burnished gutta-percha yielded an average depth of penetration of 1.5 mm. The apical seal produced by cold-burnished gutta-percha allows less than half the penetration of the best of the other techniques and gave the most consistent results.