After obtaining informed consent, the procedure begins with the administration of local anesthesia to ensure patient comfort. A standard approach involves using 2% lidocaine with 1:100,000 epinephrine, delivered either via infiltration for maxillary teeth or mental nerve block for mandibular posterior teeth. Adequate anesthesia is confirmed using a cold test or gentle probing. Once profound anesthesia is achieved, rubber dam isolation is placed to maintain an aseptic field and prevent contamination. The operative field is then disinfected with 5% sodium hypochlorite before proceeding to the access cavity preparation.

The access cavity is prepared using a high-speed diamond bur under continuous water coolant. The shape of the access cavity is determined by the tooth's anatomy, ensuring straight-line access to the canal system. Once the pulp chamber is opened, the roof is carefully removed using a round bur or ultrasonic tips, exposing the canal orifices. The chamber is then thoroughly irrigated with 2.5% sodium hypochlorite to remove any residual pulp tissue and debris. A DG16 endodontic explorer is used to locate the canal orifices, after which initial canal exploration is performed using a #10 or #15 K-file to check for patency.

Working length determination follows, utilizing an electronic apex locator (EAL) to establish the length of the canal. A confirmation periapical radiograph is taken to verify the readings. To maintain apical patience, a #10 K-file is used in a gentle watch-winding motion until it reaches the apical constriction. The glide path is then established to facilitate subsequent instrumentation. This is achieved by sequentially using hand files (#10, 15, and 20 K-files) with a balanced force technique until a #20 file moves freely to the working length. Throughout this process, frequent irrigation with 2.5% sodium hypochlorite is performed to flush out debris and maintain canal cleanliness.

Once the glide path is established, shaping of the canal begins based on the size of the initial binding file, which is the first file to engage the canal walls at the working length. If the initial binding file is #10 or #15, the apical preparation is typically completed up to a size #35, while an initial binding file of #20 may require enlargement to #40 or #50. Canal shaping is performed using a crown-down technique with rotary nickel-titanium (NiTi) instruments.

Throughout the shaping process, continuous irrigation with sodium hypochlorite to dissolve organic debris and disinfect the canal is performed with total volume of 10ml/canal. After the final shaping, the canal is dried with sterile paper points, leaving it ready for medication placement. For the subjects of GI and GII, nano-ketorolac gel and ketorolac gel respectively (Around 2mm3), placed as medicament inside the root canal while those of GIII a placebo gel is placed. Both will be retained for one week. The obturation through cold lateral compaction technique is to be carried out on the next visit.

Randomization and Blinding:

Randomization will be performed using a computer-generated sequence. The patients and outcome assessors will be blinded to the group allocation. Nano-ketorolac production

This study, a formulation containing Ketorolac Tromethamine (KT) at a concentration of 10 mg/mL were developed using Compritol 888 as distinct oleaginous phases. Span 60 was incorporated as a surfactant at a concentration of 1.5%, while the drug-to-oleaginous phase ratio was maintained at 1:2. The Solid Lipid Nanoparticles (SLNs) were formulated using high-shear homogenization to ensure optimal particle size and stability. The nano-Ketorolac will be manufactured in the college of phramaceutical sciences and drug manufacturing, Misr University for Science and Technology, , Egypt.

Statistical Analysis Data will be analyzed using SPSS software. Data will be tested for its normal distribution; accordingly, the appropriate test will be conducted. Statistical significance will be set at p < 0.05.

Ethical Considerations

• The study will be conducted in accordance with the Declaration of Helsinki.
• Ethical approval will be obtained from the Institutional Ethical Committee of Misr University for Science and Technology.
• Informed consent will be obtained from all participants before their inclusion.
• Patients will be informed of their right to withdraw at any time without consequences.
• Data confidentiality will be maintained throughout the study.

Pain management in endodontics has been extensively studied, with a focus on pharmacological interventions, anesthetic techniques, and intracanal medicaments to improve post-operative outcomes. Several studies have explored the effectiveness of NSAIDs, corticosteroids, and advanced anesthetic techniques in controlling pain, but challenges persist, particularly in cases involving necrotic pulp and apical periodontitis.

Study Design: This study will be a randomized, double-blinded, placebo-controlled clinical trial.

Participants and Setting: The study will be conducted at the clinics of Collage of Oral and dental surgery, Misr University for Science and Technology. Patients diagnosed with necrotic pulp and apical periodontitis requiring root canal treatment will be recruited.

Inclusion Criteria:

• Patients aged 18-50 years.
• Patients who are diagnosed with necrotic pulp and chronic apical periodontitis in a single-rooted tooth.
• Patients who provide written informed consent.
• Patients with no systemic diseases affecting pain perception or wound healing.

Exclusion Criteria:

• Patients with irreversible pulpitis or acute periapical abscess
• Patients with a history of NSAID or opioid use within 24 hours before treatment.
• Pregnant or lactating women.
• Patients who require more than two-visits root canal treatment due to anatomical or pathological factors.