Brief Summary (A short description for the lay public)

This study aims to find out if the type of cleaning solution used during a root canal affects the pain a patient feels the next day. A root canal procedure involves cleaning the inside of the tooth. Two common cleaning solutions are chlorhexidine (CHX) and sodium hypochlorite (NaOCl, also known as bleach). While both are effective, it is not clear if one causes more discomfort than the other.

In this research, half of the participants will have their root canal cleaned with CHX, and the other half with NaOCl. We will then ask all participants to rate their pain 24 hours after the procedure using a simple pain scale. Our goal is to see if there is a difference in pain levels between the two groups. The results will help dentists choose the best solution to make their patients more comfortable after treatment

Detailed Description (Extended technical description of the protocol)

This study is designed as a randomized controlled trial to compare the intensity of postoperative pain 24 hours after non-surgical root canal treatment using two different irrigating solutions: 2% chlorhexidine (CHX) and 5.25% sodium hypochlorite (NaOCl). The central hypothesis is that the type of irrigant influences early postoperative pain, but that this effect may be modified by patient-specific factors such as gender and age.

Methodology:

Following ethical approval and informed consent, 90 adult patients indicated for non-surgical root canal treatment will be enrolled using a non-probability consecutive sampling technique. Participants will be randomly allocated to one of two parallel groups (n=45 per group): Group A (2% CHX) and Group B (5.25% NaOCl). The sample size was calculated a priori using the pwr package in R, assuming a 95% confidence level, 80% power, and a moderate effect size based on previous studies.

A standardized endodontic protocol will be followed for all participants to ensure consistency and minimize bias:

Procedure: After administering local anesthesia (2% lignocaine with 1:80,000 adrenaline), the operative field will be isolated with a rubber dam. Standard endodontic access will be prepared, and the working length will be determined using digital radiography.

Instrumentation and Irrigation: Chemo-mechanical preparation will be performed. Irrigation will be carried out using 2 ml of the assigned solution after each instrument. The solution will be delivered using a 27-gauge side-vented needle (Max-i-Probe) kept 1-2 mm short of the working length and maintained in motion to prevent apical extrusion. The flow rate will be controlled at 2-4 ml/min.

Obturation and Follow-up: Canals will be dried with sterile paper points and obturated with gutta-percha and sealer. Participants will be provided with a questionnaire to record their pain after 24 hours using a Visual Analog Scale (VAS). Pain scores will be categorized as no pain (0), mild (1-30), moderate (31-50), or severe (51-100).

Data Analysis:

Data will be analyzed using R software (version 4.3.3). Descriptive statistics (mean, SD, frequencies) will be calculated. Comparative analyses between the two groups will be conducted using the Student's t-test for mean pain scores and the Chi-square test for categorical pain types. Statistical significance will be set at p < 0.05. A key aspect of the analysis plan includes pre-planned subgroup analyses stratified by gender and age to explore their interaction with the irrigant used.

Inclusion Criteria:

Adults aged 18-65 years

• Any gender
• Requiring non-surgical root canal treatment
• Willing to provide written informed consent
• Able to report postoperative pain using a validated pain assessment scale -

Exclusion Criteria:Known hypersensitivity or allergy to chlorhexidine or sodium hypochlorite

• Systemic conditions affecting pain perception (e.g., diabetes with neuropathy, fibromyalgia)
• Medications affecting pain perception (e.g., chronic analgesics, corticosteroids, antidepressants)
• Preoperative dental pain in the tooth scheduled for treatment
• Pregnancy or lactation
• Teeth with resorbed roots
• Mobile teeth (pathological mobility)
• Open apices