An assessment of the plastic Thermafil obturation technique. Part 2. Material adaptation and sealability

The short- and long-term apical seal of root canals obturated with softened alpha-phase gutta-percha on plastic core-carriers, Thermafil, was compared to that of laterally condensed, cold gutta-percha. Fifty-one roots from mandibular molars with separate canals, patent canal orifices and curvatures 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 files to create a continuously tapering funnel preparation. Canals were randomly obturated with Sealapex root canal sealer and either alpha-phase gutta-percha on a plastic Thermafil carrier, or standard beta-phase gutta-percha with lateral condensation. Teeth were separated into three groups of 17 each and placed in black India ink for 24 h, 7 days or after 5 months storage in water. The teeth were demineralized, rendered transparent, and apical microleakage determined by the linear measurement of dye penetration. Significant differences in microleakage were noted between the 24 h and 5-month Thermafil groups (P < 0.05), 24-h and 7-day lateral condensation groups (P < 0.05), and 24-h and 5-month lateral condensation groups (P < 0.05). There were no significant differences between the two techniques at each time interval. It was concluded that both techniques demonstrated a significant increase in apical microleakage over a 5-month period.