International Endodontk journal (1993) 26,173-178 An assessment of the plastic Thermafil obturation technique Parti Radiographic evaluation of adaptation and placement J. L. GUTMANN, W. P. SAUNDERS*, E. M. SAUNDERSt& L. NGUYEN Department of Restorative Sciences. Baylor College of Dentistry, Dallas, Texas, USA; 'Department of Adult Dental Care, Glasgow Dental Hospital and School Glasgow and f Department of Conservative Dentistry, The Dental School Dundee, UK Summary Adaptation and placement of alpha-[diase gutta-percha delivered with a plastic core-carrier, Thermafil, was compared to the lateral condensation of gutta-percha in a spraific tooth model. Fifty-one mandibular molar roots with separate canals, patent canal orifices and curva- tures greater than 15 degrees were cleaned and shaped with K-files and 2.5% sodium hypochlorite to a size 30 at the apex, and flared with Hedstrom flies to create a continuously tapering iunnel preparation. Canals were randomly obturated with Seaiapex root canal sealer and either alpha-phase gutta-percha on a plastic Thermafll carrier, or standard beta-phase gutta-percha with lateral condensation. Roots were radiographed from the proximal and evaluated by three examiners, based on established criteria for overall material adaptation, apical adaptation, and fltling material extrusion. Thermafit provided a statistically significant better over- alt canal obturation (P< 0.001), while, in the apical third, both techniques were not significantly difierent (P > 0.05). When the apical orifice was patent there was a significant propensity for the extrusion of filling materials beyond the apex (P< 0.001) with the Thermafl] technique. Keywords: extrusion, heated gutta-percha, radiographic evaluation, obturation, Thermafil. Introduction Techniques which claim to provide three-dimeasiona) obturation of the root canal system are dependent of proper cleaning and shaping prior to filling. Likewise, because all canal systems present with a multitude of irregularities, obturation techniques and materials must Correspondence; Dr James L. Gutmann. Baylor College of Dentistry. 3302 Gaston Avenue, DaUas, Texas 75246, USA, be capable of being adapted to the root canal walls, thereby providing complete obturation of the prepared space. Clinically, the determination of that obturation and adaptation is manifest exclusively by radio^aphic assessment, with parameters of evaluation including the •length of the filling material in the canal and its density, shape, and uniformity of appearance in relation to the walls of the canal (Quality Assurance Guidelines. American Association of Endodontists, 1987). Because gutta-percha obturation techniques generally require some type of condensation (lateral, vertical), their final radiographic appearance may or may not be fraught with undesirable variations in appearEmce such as sealer voids, spreader tracks, condenser voids and material welds {in the case of heated techniques) (Gutmann & Hovland 1992). While various studies have attempted to relate these aberrancies with case unaccept- abiiity and faiiure. little correlation exists at present, except for the standard that a dense, well-adapted root filling is clinically and radiographicaily acceptable. In the last 15 years, efforts have been made to produce fillings and techniques which can achieve the maximum canal adaptation with the minimum amount of leakage. In the late 1970s and early 1980s, the development of the injectable thermopiasticized gutta-percha tech- niques has made material adaptation not only much easier, but also equal in quality if not superior, to previously advocated techniques (Yee et al. 1977, Torabinejad et al, 1978, Michanowicz & Czonstkowsky 1984, Michanowicz et aJ, 1986), Even with new develop- ments, however, the presence of short root fillings and those with voids is common, primarily due to lack of operator expertise and skill in the application of these new advances (Gutmann & Rakusin 1987). In 1978 Johnson presented a simple method for the delivery of thermopiasticized gutta-percha to the properly prepared canal, which appeared to minimize or eUminate problems in the radiographic appearance of 173