The vertical compaction of warm gutta percha : a clinical and in-vitro study to determine whether back-packing results in an increased incidence of demonstrably filled lateral canals
Grossman, Jeffrey J.
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The purpose of this clinical and in-vitro study was to assess whether or not backpacking resulted in an increase in incidence of demonstrably filled accessory canals when obturating root canal systems by the vertical compaction of warm gutta percha. The clinical study involved questionnaires that were filled out by graduate endodontic students at the Endodontic Clinic of Boston University’s SchooI of Graduate Dentistry. These residents surveyed actual cases completed in the Clinic by them, in which accessory canals were found in the final radiographs of teeth that were backpacked. These final radiographs were compared with the radiographs taken at the point of deepest pack to see if the final radiographs exhibited any more accessory canals. The in-Vitro study consisted of the cleaning and shaping of 111 extracted anterior human single rooted teeth. The main apical foramen was sealed with sticky wax, and the teeth were then placed in a specially designed vacuum bottle, such that the access cavity was above the vacuum and the rest of the root was sitting within the vacuum. Methylene blue dye was then placed into the access cavity and the lateral aspect of the root was examined for traces of the dye, which would indicate the presence and location of any accessory canals. The location of the accessory canals was then marked on the root by circling the portal of exit with a graphite lead pencil mark. Twenty-five of the teeth exhibiting these accessory canals were randomly chosen and obturated by the vertical compaction of warm gutta percha. The result of the clinical study was that, of the 63 actual clinical cases surveyed, there was no incidence of an increase of demonstrably filled accessory canals after backpacking. The results of the in-Vitro study were two-fold. Firstly, 53.2% of all the extracted teeth exhibited accessory canals. Sec○ndly, the obturation of the 25 randomly selected teeth from those exhibiting accessory canals confirmed the clinical findings; that is, all the previously located and marked accessory canals were demonstrably filled at the point of deepest pack. Interestingly, some of these filled accessory canals that were extremely small had been barely visible radiographically on the extracted teeth, even when the radiographs were magnified. The conclusions, therefore, are: 1. Backpacking is unlikely to result in an increased incidence of demonstrably filled accessory canals. 2. Post spaces can be left after the point of deepest pack has been reached, with the confidence that the rest of the root canal system has been filled. 3. More accessory canals are filled by the vertical compaction of warm gutta percha than can be seen radiographically, since the bone trabeculae in-vivo can mask the existence of very fine, yet filled, branches off the main canal. 4. No other technique to date offers the ease of fabrication of a post space or the three-dimensional stability and hermetic seal than that which can be achieved by the vertical compaction of warm gutta percha.
Colored photographs included.Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, l983 (Endodontics)Bibliography: leaves l89-205.
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