Aim: This study aimed to assess the influence of continuous rotation and reciprocation kinematics on the change in substance P (SP) levels in patients diagnosed with irreversible pulpitis and symptomatic apical periodontitis (SAP).

Materials and methods: A total of twenty patients were randomly assigned into two groups: Continuous Rotation Group (CG) (n=10), where mechanical preparation was performed with the EdgeEndox7 rotary system (Albuquerque, NM, USA), and Reciprocation Group (RG) (n=10), with EdgeOne Fire reciprocating system (Albuquerque, NM, USA). Apical fluid (AF) samples were collected and changes in SP levels were quantified through ELISA. Data were statistically analyzed utilizing the independent t-test, Friedman's test, and Nemenyi post hoc test.

Results: The difference of SP levels in the reciprocating group was significantly higher when compared to the continuous rotation group (P≤ 0.05) when measured preoperatively and at the beginning of the second visit.

Conclusion: Our findings suggest that continuous rotation kinematics lead to a reduction in substance P levels.