Hard-tissue debris accumulation analysis by high-resolution computed tomography scans.

INTRODUCTION Hard-tissue debris accumulation is a potential side effect of root canal instrumentation that has not been systematically investigated. In the current communication, a method to assess this debris using high-resolution microcomputed tomography (microCT) is presented. METHODS Based on prescans, mandibular molars with joining mesial root canals and isthmuses between these were selected (n = 6). The mean volume filled with apparent hard-tissue debris after instrumentation without irrigation was calculated over 2 mm of the mesial canal system by multiplying the voxel volume with the number of voxels representing acquired radiopaque material. Backscattered electron imaging was used to compare the calcium-phosphorus content of this material with that of the root dentin in the same specimen. RESULTS Backscatter scans showed that the accumulated debris viewed in the microCT scans was consistent with root dentin. In the selected canal segments, 29.2% +/- 14.5% of the original canal volume was filled with accumulated debris, which represented a significant change from the preoperative scan (p < 0.01, one-sample t test against zero). Three-dimensional reconstructions of the microCT images visualized the accumulated hard-tissue debris in the whole canal system. CONCLUSIONS The current method appears suitable to quantitatively compare different instrumenting/irrigating regimens on dentin debris accumulation.