To compare the postoperative pain in patients undergoing root canal instrumentation with two different file systems, WaveOne and ProTaper systems.

Endodontic postoperative pain is experienced after the procedure of root canal. It is defined as an unpleasant sensation, of varying degree, experienced by the patients. Depending upon the individual and other variable, the range of postoperative pain lies between 3% to 58%. Endodontic postoperative pain could occur due to various factors that can be microbial, injured pulp, chemical, or mechanical. Factors that influence pain following a root canal include the presence of preoperative pain, apical debris extrusion, intracanal interappointment dressing extrusion, presence of periapical pathosis, hyper occlusion, and irrigant extrusion.

Although apically extruded debris can be reduced through various means, it cannot be completely avoided. Thus, increasing the incidence of postoperative pain in patients. The debris produced during apical extrusion contains necrotic tissue, dental chips, microbes, pulp tissue, and canal irrigants. The infected debris may disturb the balance between the microbes and the immune system, leading to acute exacerbation.

Manual steel K files tend to produce more debris, causing a high risk of postoperative discomfort. Nickel-titanium rotary instruments powered by the engine have various advantages including; time-saving, preservation of root canal anatomy, and homogeneous preparation of the shape of the root canal. The debris produced by these instruments is potentially lesser than the manual files. Mainly because they have rotary action and they excavate the debris with the help of their flutes. Repeated irrigation along with the action of an engine-driven instrument, has the potential to decrease postoperative pain. WaveOne reciprocating file instruments have potential advantages including reduced fatigue, resistance to fracture, less debris extrusion, good shaping ability, no cross-contamination (single use), and reduced cost.

Relation between debris extrusion and postoperative care has not been established in any previous study. This study is aimed at comparing the use of ProTaper Universal and WaveOne system, for preparation of permanent human teeth during root canal procedure and their effect on postoperative pain.

Inclusion Criteria:

1. Patients with unremarkable/ noncontributory medical history
2. Healthy persons between the ages of 18 and 60 years
3. Maxillary and mandibular molar teeth diagnosed with symptomatic irreversible pulpitis.
4. Patients not having taken any medication for 6 hours before treatment
5. No allergies to the drugs or dental material being used in the treatment

Exclusion Criteria:

1. Patients who had taken analgesics on anti-inflammatory drugs within the last 12 hours
2. Pregnant women and patients with immunocompromised health state
3. Patients having severe malocclusion associated with traumatic occlusion
4. Teeth with calcified canals
5. Teeth with periapical radiolucency
6. Teeth with root resorption
7. Teeth previously undergone root canal treatment

individual participant data to not be disclosed due to privacy reasons and data sharing for statistical analysis to be done with codenames.

The patients did not know which file system was used in their treatment. The investigator was also not disclosed the intervention's name; rather, a code name was given to them.

Outcomes accessor also did not know the exact name but was provided with a code name.