Effect of Different Apical Motion Algorithms on Postoperative Pain After Root Canal Treatment

Detailed Description

Postoperative pain remains one of the most relevant short-term outcomes in endodontic treatment and may be influenced by several mechanical and biological factors during root canal preparation. Among these factors, the kinematics of nickel-titanium instrumentation systems and the apical motion algorithms integrated into endodontic motors may affect debris extrusion, apical stress, and periapical tissue irritation. Although different motor settings are routinely used in clinical practice, the influence of these apical motion modes on postoperative pain has not been sufficiently clarified.

This prospective, randomized, double-blind clinical trial is designed to investigate the effect of different apical motion algorithms used during root canal treatment on postoperative pain. The study will focus on mandibular premolar teeth diagnosed with chronic apical periodontitis and requiring primary root canal treatment. Participants will be randomly assigned to one of six treatment groups according to the kinematic system used during canal preparation (rotary or reciprocating) and the apical motion mode of the endodontic motor (auto apical stop, auto apical reverse, or off mode).

All treatments will be performed by the investigator using a standardized clinical protocol under local anesthesia and rubber dam isolation. Working length determination, irrigation, ultrasonic activation, canal preparation, obturation, and coronal restoration procedures will be standardized in order to minimize operator- and technique-related variability. A single nickel-titanium file system will be used in all groups to reduce the confounding effect of instrument design.

The main purpose of this study is to determine whether the use of different apical motion modes, under rotary and reciprocating kinematics, results in differences in postoperative pain intensity. In addition, the study seeks to provide clinically relevant evidence regarding whether these motor settings influence patient comfort after treatment. The findings are expected to contribute to the optimization of endodontic instrumentation protocols and to support more evidence-based selection of motor settings in daily clinical practice.

Inclusion criteria

• Adults aged 18-70 years
• Systemically healthy individuals (ASA I)
• Mandibular premolar teeth diagnosed with chronic apical periodontitis
• Periapical Index (PAI) score ≥ 3 confirmed radiographically
• Teeth indicated for single-visit root canal treatment
• Patients able to understand and complete the Visual Analog Scale (VAS)
• Written informed consent provided

Exclusion criteria

• Patients with systemic diseases or medically compromised conditions
• Pregnant or breastfeeding women
• Patients with uncontrolled diabetes mellitus
• Use of analgesics or antibiotics within the previous 7 days
• Teeth with root resorption
• Teeth with immature apices
• Previously endodontically treated teeth
• Patients unable to provide informed consent