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Effect of large instrument use on shaping ability and debris extrusion of rotary and reciprocating systems

AIM
The aim of the present study was to evaluate the effect of large instrument use on the shaping ability and apical debris extrusion of rotary and reciprocating systems in oval-shaped root canals.


METHODS
Forty-five mandibular premolars, with an 18-mm long, oval-shaped single canal, and apical diameter ranging from 300 to 350 μm, were separated into three groups (n=15), according to the system used: ProTaper Universal group, F5 (0.50/0.05); ProTaper Next (PTN group), X5 (0.50/0.06); and Reciproc (RC group), R50 (0.50/0.05). Cone-beam computed tomography was performed before and after preparation to analyze apical transportation (AT), centering ability (CA), and change in root canal diameter (CRCD). For evaluating apical debris extrusion, the roots were coupled to pre-weighed glass receptacles to collect the extruded debris during preparation.


RESULTS
All systems promoted AT and apical debris extrusion; the latter was higher for the PTN group (P<.05). No system presented perfect CA. The RC group demonstrated the largest CRCD (P<.05).


CONCLUSIONS
As consequences of their use, the large instruments promoted undesirable AT and debris extrusion, irrespective of the system used to perform root canal preparation. Moreover, no system was able to remain perfectly centralized within the root canal.