Thermafil Retreatment Using a New “System B” Technique or a Solvent

By Wolcott J, Himel V, Hicks M

Date: 02/1999
Journal: JOE


Purpose: to compare the efficacy and time required to retreat Thermafil with plastic carriers using system B or solvent technique.

N=  52 extracted mandibular 1st  molars with 1 canal.

Materials & Methods:

•After access, teeth were instrumented with 0.4 profile series 29, then instrumented with #35 NiTi apical preparation.

•Obturated with thermafil obturators and thermaseal closed with cotton and cavit, kept for 14 days in an obturators.

Retreatment technique:

Solvent GP: heated plugger was used to create 2 mm depth for the solvent, then 5 mm of gutta percha buccal and lingual to the carrier was removed using #30,#50 hand files (NiTi). Then both files were firmly seated in buccal and lingual to the carrier and rotated in clockwise manner to engaged the carried material and then files along carrier were pulled as 1 unit . And retreatment was considered finished after that.

System B GP: medium-fine plugger was introduced at 225 C  to a depth of 10-15 mm, then size 50 and 55 were introduced as solvent group, if retrieval was unsuccessful the process was repeated again.

•Time was measured, then teeth were embedded in resin then the sections were pictured at 40x magnification and cross-sectioned of the canals were compared to the cross section of the canal.

Most highlighted Results:

•System B technique (1.8 min )was less than solvent technique (3.6 min). •The difference in the amount of gutta percha removed was not significant between 2 techniques.

Clinical significance

Both techniques seems to be effective, one thing that might have made system B technique faster is that gutta percha was softened to a significantly more depth.