This study compares post-operative pain in teeth with asymptomatic irreversible pulpitis treated with versus without apical patency during root canal treatment.

Asymptomatic irreversible pulpitis is a condition where the dental pulp is inflamed but the patient does not feel spontaneous pain. Apical patency is a technique where a small flexible file is passed gently beyond the tip of the tooth root during cleaning and shaping.

One hundred fifty patients with premolar teeth diagnosed with asymptomatic irreversible pulpitis were randomly assigned to one of two groups. The Apical Patency Group received root canal treatment with a #10 K-file passed 0.5 mm beyond the working length after each rotary instrument. The Non-Patency Group received the same treatment but no instrument was passed beyond the working length.

The primary outcome is pain incidence at 24 hours measured on a Numerical Rating Scale (0 to 10, where 0 is no pain and 10 is worst pain imaginable). Secondary outcomes include pain intensity at 6,12,24,48,72 hours, number of ibuprofen tablets taken for pain, and time until pain completely resolves.

The study aims to determine whether the apical patency technique reduces post-operative pain compared to standard treatment without patency.

This was a single-blind, parallel-group, 1:1 allocation ratio randomized controlled trial conducted at the Department of Operative Dentistry, Bolan Medical College and Hospital, Quetta, Pakistan, from July 2025 to February 2026.

Study Population: Patients aged 20-50 years, classified as American Society of Anesthesiologists Physical Status I or II, with maxillary or mandibular first or second premolars requiring non-surgical root canal treatment. Asymptomatic irreversible pulpitis was confirmed by deep caries, exaggerated and prolonged response (≥10 seconds) to cold testing, absence of spontaneous pain, no tenderness to percussion, and no periapical radiolucency.

Exclusion Criteria:Uncontrolled diabetes mellitus (HbA1c >7%), uncontrolled hypertension, chronic pain syndromes, regular analgesic/corticosteroid use within 2 weeks, immature apex, root resorption/fracture, curvature >30°, calcified canals, pocket depth >4 mm, non-restorable crown, retreatment cases, inability to achieve anesthesia.

Sample Size:Based on previous study reporting pain incidence of 56% without patency and 35.7% with patency (α=0.05, power=0.80, 10% attrition), 75 patients per group (total N=150) were enrolled.

Randomization and Blinding: Computer-generated randomization sequence with sequentially numbered opaque sealed envelopes. Patients and outcome assessors were blinded to group allocation. Treating operators could not be blinded due to the nature of the intervention.

ntervention - Apical Patency Group (APG, n=75 allocated):After each rotary instrument (ProTaper Next X1 17/.04, X2 25/.06), a pre-curved #10 K-file was passively passed to working length plus 0.5 mm. No filing motion was performed.

Intervention - Non-Patency Group (NPG, n=75 allocated):No instrument was intentionally passed beyond working length. Recapitulation was performed only to working length.

Common Procedures (Both Groups):Working length determined electronically (Root ZX) and confirmed radiographically, set at 0.5 mm short of electronic "0.0" reading. Irrigation with 5 mL 3% sodium hypochlorite after each file via 30-gauge side-vented needle placed 1 mm short of working length. Final rinse with 5 mL 17% EDTA for 1 minute followed by 5 mL sterile saline. Obturation with single-cone technique using matched-taper gutta-percha and bioceramic sealer (iRoot SP). Temporary restoration with 3-4 mm Cavit reinforced with glass ionomer cement.

**Follow-up:Seven patients were lost to follow-up (3 from APG, 4 from NPG; attrition rate 4.7%). Per-protocol analysis included 72 patients in APG and 71 patients in NPG.

Outcome Measures:Primary outcome: pain incidence at 24 hours (Numerical Rating Scale ≥1). Secondary outcomes: pain intensity (NRS 0-10) at 6,12,24,48,72 hours; total analgesic consumption (400 mg ibuprofen tablets); time to pain resolution (hours until NRS=0); flare-up incidence (unscheduled visit, NRS≥7).

Statistical Analysis: Per-protocol analysis primary; ITT sensitivity analysis performed. Chi-square test for primary outcome; repeated-measures ANOVA with Bonferroni correction (adjusted α=0.005); Mann-Whitney U for analgesics; Kaplan-Meier with log-rank for time to resolution. SPSS 26.0.

Inclusion Criteria:

• - Age 20 to 50 years
• American Society of Anesthesiologists Physical Status I or II
• Maxillary or mandibular first or second premolar requiring non-surgical root canal treatment
• Confirmed asymptomatic irreversible pulpitis (deep caries, prolonged cold test response ≥10 seconds, no spontaneous pain, no periapical radiolucency)
• Written informed consent obtained

Exclusion Criteria:

• - Uncontrolled diabetes (HbA1c >7%) or uncontrolled hypertension
• Chronic pain syndromes or immunosuppression
• Analgesic/corticosteroid/antidepressant use within 2 weeks
• Immature apex, root resorption, root fracture, or curvature >30 degrees
• Calcified canals, pocket depth >4 mm, mobility >Grade I, or non-restorable crown
• Retreatment cases or inability to achieve anesthesia
• Pregnancy

No plan to share individual participant data.

Participant and Outcomes Assessor (Select "Single Blind" if that is the only option, or check both "Participant" and "Outcomes Assessor" if the form allows multiple selections)