Submucosal Cryotherapy and Anti-inflammatory Drugs for Postoperative Pain Following Root Canal Treatment in Maxillary Molars

Participants will receive local anesthesia using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 administered by buccal infiltration, with supplemental palatal infiltration if needed. Standardized single-visit root canal treatment will be performed without additional submucosal cryotherapy or anti-inflammatory drug injections.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Participants will receive standard local anesthesia followed by a single submucosal injection of 1 mL cold normal saline (2-5°C) into the buccal vestibule adjacent to the affected maxillary molar before standardized single-visit root canal treatment.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Submucosal cryotherapy will be performed through a single injection of 1 mL sterile normal saline cooled to 2-5°C into the buccal vestibule adjacent to the affected maxillary molar before root canal treatment. The intervention is intended to provide localized cooling to reduce postoperative inflammation and pain. Cryotherapy will be administered alone or in combination with an anti-inflammatory drug according to group allocation.

Participants will receive standard local anesthesia followed by a single submucosal injection of 1 mL diclofenac sodium (25 mg/mL; total dose 25 mg) into the buccal vestibule adjacent to the affected maxillary molar before standardized single-visit root canal treatment.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Diclofenac sodium will be administered as a single preoperative submucosal injection of 1 mL at a concentration of 25 mg/mL (total dose: 25 mg) into the buccal vestibule adjacent to the affected maxillary molar. It will be administered alone or in combination with submucosal cryotherapy according to group allocation to evaluate its effects on postoperative pain and inflammatory response.

Participants will receive standard local anesthesia followed by a single submucosal injection of 1 mL dexamethasone sodium phosphate (4 mg/mL; total dose 4 mg) into the buccal vestibule adjacent to the affected maxillary molar before standardized single-visit root canal treatment.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Dexamethasone sodium phosphate will be administered as a single preoperative submucosal injection of 1 mL at a concentration of 4 mg/mL (total dose: 4 mg) into the buccal vestibule adjacent to the affected maxillary molar. It will be administered alone or in combination with submucosal cryotherapy according to group allocation to evaluate its effects on postoperative pain and inflammatory response.

Participants will receive standard local anesthesia followed by submucosal administration of cold normal saline (1 mL at 2-5°C) and diclofenac sodium (1 mL at 25 mg/mL) into the buccal vestibule adjacent to the affected maxillary molar before standardized single-visit root canal treatment. The interventions will be administered separately or sequentially according to the finalized study protocol.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Submucosal cryotherapy will be performed through a single injection of 1 mL sterile normal saline cooled to 2-5°C into the buccal vestibule adjacent to the affected maxillary molar before root canal treatment. The intervention is intended to provide localized cooling to reduce postoperative inflammation and pain. Cryotherapy will be administered alone or in combination with an anti-inflammatory drug according to group allocation.

Diclofenac sodium will be administered as a single preoperative submucosal injection of 1 mL at a concentration of 25 mg/mL (total dose: 25 mg) into the buccal vestibule adjacent to the affected maxillary molar. It will be administered alone or in combination with submucosal cryotherapy according to group allocation to evaluate its effects on postoperative pain and inflammatory response.

Participants will receive standard local anesthesia followed by submucosal administration of cold normal saline (1 mL at 2-5°C) and dexamethasone sodium phosphate (1 mL at 4 mg/mL) into the buccal vestibule adjacent to the affected maxillary molar before standardized single-visit root canal treatment. The interventions will be administered separately or sequentially according to the finalized study protocol.

Local anesthesia will be administered using one carpule of 4% articaine hydrochloride with epinephrine 1:100,000 by buccal infiltration before single-visit root canal treatment. Supplemental palatal infiltration will be provided if needed, and any additional anesthetic administration will be recorded. This standard anesthetic regimen will be used in all six study groups.

Submucosal cryotherapy will be performed through a single injection of 1 mL sterile normal saline cooled to 2-5°C into the buccal vestibule adjacent to the affected maxillary molar before root canal treatment. The intervention is intended to provide localized cooling to reduce postoperative inflammation and pain. Cryotherapy will be administered alone or in combination with an anti-inflammatory drug according to group allocation.

Dexamethasone sodium phosphate will be administered as a single preoperative submucosal injection of 1 mL at a concentration of 4 mg/mL (total dose: 4 mg) into the buccal vestibule adjacent to the affected maxillary molar. It will be administered alone or in combination with submucosal cryotherapy according to group allocation to evaluate its effects on postoperative pain and inflammatory response.

Postoperative pain intensity will be assessed using an 11-point Numeric Rating Scale (NRS), ranging from 0 (no pain) to 10 (worst imaginable pain). Higher scores indicate greater pain intensity. Participants will record their pain intensity at predefined postoperative intervals, and NRS scores will be compared among the six study groups.

Interleukin-6 (IL-6) levels will be measured in pulpal blood samples collected under aseptic conditions after access cavity opening during root canal treatment. Samples will be stored at -20°C and analyzed using enzyme-linked immunosorbent assay (ELISA). IL-6 levels will be compared among the six study groups to evaluate the local inflammatory response.

The occurrence of postoperative flare-up following single-visit root canal treatment will be recorded. The number and percentage of participants experiencing flare-up will be determined and compared among the six study groups.

Participants will be instructed to avoid taking analgesics unless necessary. Any postoperative rescue analgesic intake will be recorded. The number and percentage of participants requiring rescue analgesics will be compared among the six study groups.