This study will evaluate the outcome of calcium silicate sealer-based obturations in root canal retreatment.

Calcium silicate sealer-based obturations have shown promising performance in primary root canal treatments, but there is a lack of prospective studies evaluating their effectiveness in secondary root canal treatments, which often involve more persistent microbial challenges. The aim of this study is to assess the clinical and radiographic outcomes of calcium silicate sealer-based obturations in root canal retreatment and to identify potential prognostic factors for healing.

Objectives:

1. To determine the success rate of calcium silicate sealer-based obturations in root canal retreatment.
2. To compare the observed outcomes with previously published retreatment studies using conventional obturation techniques.
3. To identify potential prognostic factors associated with favourable or unfavourable outcomes.

This will be a prospective cohort study conducted at Jaber Al-Ahmed Dental Center. Informed written consent will be obtained from all participants. All nonsurgical root canal retreatments will be performed by a specialist endodontist using a calcium silicate-based sealer (CeraSeal, Meta Biomed) following current evidence-based standards. Treatments will be recorded in a secure database, and all cases will be followed for a minimum of 12 months.

Clinical and radiographic records will be reviewed, and eligibility will be determined according to predefined inclusion and exclusion criteria. All patient data will be anonymized before extraction and analysis.

The primary outcome at 12 months will be the proportion of teeth classified as having a favourable outcome. This outcome will serve as the dependent variable in logistic regression models evaluating the associations between healing and potential predictors, including age, sex, tooth type, periapical status, preoperative pain, quality of the previous root filling, sinus tracts, apical patency, final apical preparation size, and sealer extrusion. Separate univariable logistic regression models will be performed for each predictor. A multivariable logistic regression model will then be constructed to evaluate the combined effects of independent variables, with exploratory assessment of two-way interactions.

This study was designed as a single-arm prospective outcome investigation with the primary endpoint being the proportion of teeth exhibiting a favourable outcome. A precision-based approach was used to determine the required sample size. An anticipated healing rate of 80 percent was assumed based on systematic reviews and prospective cohort studies that report healing rates between 77 and 87 percent for nonsurgical retreatment.

Using PASS (version 25.0.3; NCSS, LLC, Kaysville, Utah, USA) with the One Proportion - Confidence Interval procedure (two-sided 95 percent confidence level, Wilson method), a sample size of 95 teeth was required to estimate the healing proportion with a target precision of approximately ±8 percentage points. Allowing for up to 30 percent attrition, the planned enrolment was set at 136 teeth, which is expected to yield at least 95 evaluable cases. This target aligns with sample sizes used in previous prospective clinical studies on endodontically retreated teeth.

Inclusion Criteria:

• Participants must be 18-65 years of age at the time of recruitment
• Participants must have a classification of I or II on the American Society of Anesthesiologists (ASA) physical status classification system
• Participants must not have known allergies to any materials used in the study
• Participants must agree to participate in the study by signing a consent form
• Participants must have good oral hygiene
• All types of permanent teeth that require root canal retreatment are included (incisors, canines, premolars & molars)
• The teeth must be restorable and have fully formed roots with no advanced periodontal disease

Exclusion Criteria:

• ASA classification of III or more
• Pregnant or breastfeeding women
• Patients who are unable to give consent
• Patients who have advanced periodontal disease or teeth with more than 5mm probing
• Teeth with incomplete root formation
• Teeth that have a poor restorative prognosis
• Teeth presenting with signs of a vertical root fracture
• Teeth with blocked or non-negotiable canals
• Teeth with broken instruments
• Teeth with iatrogenic perforations
• Teeth requiring posts or extensive prosthetic rehabilitation
• Teeth with cracks
• Teeth with internal or external root resorption
• Teeth with uncontrollable exudate

Patients who present with symptomatic teeth and require root canal retreatment will be assessed based on inclusion and exclusion criteria.

IPD will not be available to other researchers.