Comparison of Postoperative Pain With or Without Apical Patency Technique in Asymptomatic Necrotic Teeth

Cleaning and shaping is an integral part of root canal therapy that involves mechanical instrumentation and irrigation of root canal system.1 The apical portion of root canal system is challenging to properly prepare and debride with mechanical instrumentation because of anatomical complexity 2. Dentinal and pulpal debris can be pushed to apical portion during mechanical instrumentation of root canal system, blocking access to apical third which may lead to procedural errors such as loss of working length, perforations, ledge formation and transportation.3, 4 Accumulation of pupal and dentinal debris causing blockage in apical third of the root canal can be prevented only when patency of apical foramen is maintained through apical patency file technique 2, 4, 5.

Apical patency (AP) is a technique in which the apical portion of the canal is maintained free of debris by recapitulation with a small file through the apical foreman 4, 6 thus preventing incidence of procedural accidents, maintaining the required working lengths, improving tactile sensation and facilitating irrigation of apical third of the canal 3-5, 7. In-case of infected or necrotic pulp, it also helps remove the bacterial biofilms around the apical foramen 2, 4. It's importance was also reflected from study conducted by Arias et al there was less postoperative pain when AP was maintained in non-vital pulp 5. Patency file also results in less gas bubbles presented in root canal during cleaning and shaping procedures that could resultin less contact of irrigation solutions with the root canal walls 7, 8.

To maintain apical patency a small flexible K-file (usually a size #10) is set at 1 mm longer than the final working length is intentionally and passively moved through the apical constriction without binding and widening it after each instrument before irrigation.3-5, 9, 10 One of the problems associated with maintaining apical patency is the possible displacement of infected debris through the apical foramen causing acute apical inflammatory response that may lead to postoperative pain2, 5, 9. Furthermore, it may result in damage and transportation of the apical foramen11. However, no such complication as postoperative pain or damage and transportation of apical foramen, resulted 12,13.

Several studies have evaluated the effect of maintaining apical patency on postoperative pain. When patency was maintained in teeth with nonvital pulp, Arias et al5 reported significantly less postoperative pain; however, the author did not describe the periapical status of teeth. While in another RCT did not reveal any significant difference in postoperative pain in teeth with necrotic pulp and apical periodontitis; however, Arora et al13 conducted the study on 68 participants. In addition, the canals preparation was either carried out with hand files 5 or continuous rotary system 13. In a study by Yaylali at al3, who also reported significantly less postoperative pain for first 5 days while maintaining patency; however, the author used reciprocating system for canal preparation and VAS scale for pain severity. In addition, the teeth were not asymptomatic pre-operatively. While in another RCT by Shubham at al18 reported significantly higher pain while maintaining apical patency.

Considering the limitations and conflicting results in previous studies. Hence, this study hypothesizes that there is no difference in terms of post-operative pain between either maintaining apical patency or not. This RCT was designed to evaluate the effect of maintaining apical patency on postoperative pain in teeth with pre-operatively asymptomatic necrotic pulp and apical periodontitis. The primary outcome measure of this study will be to determine the incidence and severity of post-operative pain in both apical patency and non-patency groups; and secondary outcome measure will be to assess post-operative use of analgesics in both groups.