Purpose: to compare the kinematic effect of NiTi instruments with reciprocating motion(R) and continuous rotation (CR) motion in cyclic fatigue resistance, shaping ability for canal transportation, apical debris extrusion, and dentinal defects or cracks
•Inclusion criteria were stated
•Electronic search in MEDLINE data base and hand searching
•n: 12 studies for cyclic fatigue, 19 for shaping ability, 14 for apical debris extrusion, 13 for dentinal defects
•Most of the studies concluded in a higher cyclic fatigue resistance with R than CR; one study contradicted their findings
•Canal transportation was less using R in 9 invitro studies and no sig difference in 7 studies (ex vivo)
•Most of the studies that evaluated Extrusion of apical debris found no significant difference between the two motions
•6 studies found less dentinal defect in R than CR and 5 studies found no significant difference
•Apical transportation greater than 300 mm could negatively affect the sealing of the obturation. In which both motions resulted in less than the limit that affects clinical results
•Instruments with R motion showed better resistance to cyclic fatigue than CR motion in laboratory studies.
•Reciprocating and continuous rotating motion would be used in the clinic without any significant difference in shaping ability and transportation tendency.