Purpose: To determine the amount of dentin removed at 3 different canal levels, canal deviation, and canal transportation of initial instrumentation and during retreatment
n: 20 single canal straight rooted human teeth (L: 10 canine and Max Central, S: 10 mand Inc and Max L inc)
•Teeth were imbedded in clear acrylic resin and die stone jig. Teeth were sectioned at 3 levels coronal middle and apical.
•Teeth were prepared with GG to 10-14mm into the canal and hand files in a SB tech and obturated with GP cones with Roth sealer then teeth were stored for 2 months at 37⁰C and in 100% humidity.
•Retx tech: chloroform was used with files and barbed broaches and re-instrumented with files 1-2 sizes larger than initial file.
•Radiographs were taken, traced, and quantified for: the increase in the canal area and direction of movement by Sonic digitizer before and after instrumentation and after re-instrumentation.
Most highlighted Results:
•The apical area increased significantly more (25.4%) than the coronal or middle
•In small canals the coronal area showed the most deviation and was the least in the middle
•In large canals the middle section showed the most deviation and the least in the coronal portion
•Most of the deviation were after initial instrumentation. Retreatment usually resulted in much smaller deviations maintaining the direction of deviation of the initial tx.
If one is considering retreating one’s own failure, it is unlikely that debridement of previously undebrided areas will take place.