Reciprocating root canal technique induces greater debris accumulation than a continuous rotary technique as assessed by 3-dimensional micro-computed tomography.

INTRODUCTION The ability of single-file, reciprocating instruments to remove inorganic debris is uncertain. By using micro-computed tomography (microCT), this study compared the 3-dimensional distribution, quantity, and density of remaining inorganic debris in the mesial root of mandibular molars after instrumentation. A single reciprocating file was compared with a multifile rotary instrumentation technique. METHODS Teeth were selected for instrumentation using reciprocating or rotary instruments (n = 19). Teeth were scanned using microCT before and after instrumentation. Through shape recognition and superimposition image analysis techniques, remaining inorganic tissue debris was identified, quantified, and visualized 3-dimensionally, mapping debris to its location. The use of a density phantom enabled the debris density to be calculated, giving a measure of compactness. RESULTS After single-file instrumentation, an average of 19.5% debris remained in the canal compared with 10.6% with the multifile technique (P = .01) and at an average density of 1.60 g/m(3) compared with 1.55 g/m(3) for the multifile system (P > .05). Isthmuses, protrusions, and irregularities in the canal wall were repeatedly seen at the locations of debris accumulation. CONCLUSIONS In canals with a high prevalence of isthmuses and protrusions, using multifile rotary systems may be preferred over reciprocating files because it can yield cleaner canals with less debris accumulation.