An in vitro evaluation of a prototype Delrin carrier for the Thermafil obturation system

Objective: To produce and test a prototype carrier for the Thermafil obturation system. Method and Materials: A prototype carrier was created in a new plastic material (Delrin) with a new profile design made up of 15 intersecting cones of decreasing diameter and a 0.06 taper. Thirty extracted premolar teeth were root filled, 15 with obturators with the prototype carriers and 15 with the traditional Thermafil obturators. The samples were made transparent and examined with an optical microscope equipped with a millimeter scale in order to observe the aspect of gutta-percha stripping from the carrier and evaluate its degree by measuring the length of carrier deprived of gutta-percha on the buccal, mesial, distal, and lingual root surface. The analysis of variance (ANOVA) test was carried out for statistical analysis. Results: The prototype carriers made contact with the dentinal walls (mean length of stripping: 5.80 mm for size 25, 3.42 for 30, and 1.40 for 35) but less than the traditional Thermafil obturators (mean length of stripping: 6.68 mm for size 25, 7.98 for 30, and 6.86 for 35). The ANOVA test revealed no statistically significant difference between groups for P < .01. The prototype carriers contacted the walls in short horizontal band-shaped areas around the circumference, while the Thermafil obturators had contact in long vertical strip-shaped areas. Conclusion: The prototype carrier, contacting the dentinal walls in short areas all around the circumference, allows the centering of the obturator into the root canal.