Residual Filling Material in Dentinal Tubules after Gutta-percha Removal Observed with Scanning Electron Microscopy

Introduction: In cases of failed root canal treatment, endodontic retreatment of the root canal system is necessary. The present study aimed to assess variation in the incidence and depth of residual filling material in dentinal tubules after gutta-percha removal with H-files, the ProTaper Universal System (Dentsply Maillefer, Ballaigues, Switzerland), and the SybronEndo K3 System (SybronEndo Corporation, Orange, CA). Methods: Forty human mandibular premolars with single straight root canals were prepared with K-files (up to size 40) using the step-back technique and filled by cold lateral condensation with gutta-percha and AH Plus sealers (Dentsply DeTrey, Konstanz, Germany). After 1 year, the 40 teeth were divided into one control group and 3 retreatment groups (n = 10 each). Gutta-percha was removed using H-files, the ProTaper Universal System, or the SybronEndo K3 System. The teeth were sectioned, and the incidence and depth of residual filling material in the dentinal tubules were measured under scanning electron microscopy. Results: The depth of filling material in the dentinal tubules did not differ significantly among groups (P >.05). Residual filling material was present in significantly more dentinal tubules in the ProTaper (P =.043) and K3 groups (P =.001) than in the Hfile and control groups. Conclusions: The ProTaper Universal System and the SybronEndo K3 System left filling material in a greater proportion of dentinal tubules than did H-files. (J Endod 2012;38:293-296)