Reciprocating kinematics leads to lower incidences of postoperative pain than rotary kinematics after endodontic treatment: A systematic review and meta-analysis of randomized controlled trial

Background: Extrusion of infected debris into the periapical tissue has been cited as the major cause of postoperative pain, regardless of instrumentation technique.
Aim: Comprehensively review two different kinematics of instrumentation (reciprocating and rotary) and association to the postoperative pain after endodontic treatment.
Methods: Two investigators performed a systematic review with meta-analysis. MEDLINE/PubMed, Cochrane Library, and Scopus supplied relevant data from studies published until February 2018 to answer the PICO question. Primary outcome was overall postoperative pain, and the secondary outcomes were nature of the pain (mild, moderate, and severe) at 12, 24, and 48 h.
Results: Ten randomized clinical trials fulfilled eligibility criteria, and five of them were submitted in the meta-analysis. Primary outcome indicated that reciprocating system results in less postoperative pain compared to rotary system (P < 0.05). As a secondary outcome, there was no statistical difference for mild, moderate, and severe pain after 12 and 24 h using reciprocating or rotary systems (P > 0.05). However, the reciprocation system showed less severe pain after 48 h (P < 0.05).
Conclusion: Rotary motion had a negative impact on postoperative pain after endodontic treatment. Furthermore, after 48 h, more patients presented severe pain under rotary motion. More randomized clinical studies would be helpful.