Date of Award


Document Type


Degree Name

Master of Science (MS)




College of Dental Medicine

First Advisor

Joe W. Krayer

Second Advisor

Marc E. Levitan

Third Advisor

Joseph E. Assad


Introduction: A preparation technique allowing for a predictable thermoplastic obturation length while ensuring a three-dimensional fill would be of clinical value. Methods: This in vitro study was conducted using 80 extracted mature and patent human 1st and 2nd maxillary and mandibular molar teeth with mesiobuccal (MB) roots exhibiting 20°- 45° canal curvature using Schneider's method. Teeth were randomly divided into 4 experimental groups (n=20). Groups 1 and 3 were prepared using a standard taper preparation (STP) to size 40/04 at working length (WL). Groups 2 and 4 were prepared using a varied taper preparation (VTP) to size 40/02 at WL. Groups 1 and 2 were obturated with RealSeal 1™ (RS-1) per manufacturer's specifications. Groups 3 and 4 were obturated with Thermafil® Plus (TP) per verbal communication with the manufacturer. Extrusion of material was evaluated radiographically and microscopically (5X) and assessed ordinally as follows: (1) +/- 1.0 mm from WL, and (2) > 1.0 mm beyond WL. Statistical significance of data was set at P = .05. Results: The data for all groups showed statistically significant differences for overextension in STP groups compared to VTP groups {odds ratio STP:VTP=17.3:1) when controlling for type of material {P < .001), and for overextension in TP groups compared to RS-1 groups (odds ratio TP:RS-1=40:1) when controlling for type of preparation (P < .001). Conclusions: Results of this study demonstrated using VTP compared to STP1 and RS-1 compared to TP, in curved canals of MB molar roots significantly decreases the occurrence of extrusion while maintaining three-dimensional obturation of the root canal system. The clinical applications from this study include the following: when utilizing RS-1 either preparation type may be used and when using TP it is recommended to use a VTP to help minimize overextension of filling material.


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