Objectives: The aim of this study was to compare the amount of apically extruded debris and
the patterns of smear layer formation following the preparation of root canals in extracted human
teeth using ProTaper Next, Twisted file, and a reciprocating single-file system.
Material and Methods: Forty-five freshly extracted human single-rooted maxillary incisors
were divided into 3 groups (n=15) then instrumented using Protaper Next, Twisted files, and
Reciproc. The extruded debris were collected in a pre-weighed Eppendorf tubes. The tubes were
stored in an incubator at 70 °C for 2 days before weighing the dry debris using analytical balance.
The debris weight was determined by subtracting the initial weight from the final weight. Root
samples were splitted longitudinally into two halves by making grooves then root halves (cervical,
middle and apical) thirds were examined using Environmental Scanning Electron Microscope
ESEM (FEI Quanta 250 FEG, Berlin, Germany) at ×1500 magnification. All the data were subjected
to statistical analysis using Chi-squared, Fisher`s Extract.
Results: The three tested rotary nickel titanium files produced comparable amount of debris
extrusion and smear layer patterns covering the root canal dentin walls. Apical third showed the
heaviest accumulation of smear layer.