Outcome of Calcium Silicate Sealer-Based Obturation in Root Canal Retreatment: A CBCT-Based Prospective Cohort Study

Calcium silicate sealers (CSS) have become the dominant approach to root canal obturation in many specialist practices, yet evidence on their performance in nonsurgical retreatment is sparse and CBCT-based assessment remains uncommon. The behaviour of a CSS-based retreatment protocol under three-dimensional assessment is therefore poorly characterised.

To evaluate the clinical and radiographic outcomes of nonsurgical retreatment with a calcium silicate sealer using both periapical (PAI) and CBCT (CBCT-PAI) indices, and to identify factors associated with CBCT-assessed success.

One hundred and thirty-six previously root canal treated teeth in 97 patients were enrolled at Jaber Al-Ahmed Dental Center, Kuwait, between March 2023 and December 2024. A single endodontist performed retreatment using a standardised sealer-based obturation protocol with a calcium silicate sealer (CeraSeal). Teeth were re-examined clinically at 12-24 months. Two calibrated specialists independently scored periapical radiographs (PAI) and small-field-of-view CBCT (CBCT-PAI), classifying each tooth as Healed, Healing or Diseased under both systems to yield four endpoints (PAI-loose, PAI-strict, CBCT-loose, CBCT-strict). The CBCT endpoints were primary and PAI endpoints descriptive. Multivariable analysis used Hosmer-Lemeshow purposeful selection with generalised estimating equations (CBCT-strict) and Firth's penalised logistic regression (CBCT-loose).

Of 136 enrolled teeth, 118 in 80 patients were re-examined (tooth-level recall 86.8%, patient-level recall 82.5%, mean follow-up 13.9 months). Success rates were 93.2% (PAI-loose), 89.0% (CBCT-loose), 83.1% (PAI-strict) and 64.4% (CBCT-strict). Each one-point increase in pre-operative CBCT-PAI reduced the adjusted odds of CBCT-strict success (adjusted OR 0.57, 95% CI 0.41-0.81, p = 0.001). Non-molar teeth had higher odds of CBCT-loose success than molars (OR 4.69, 95% CI 1.30-25.01, p = 0.017). A pre-specified sensitivity analysis recoding pre-operative CBCT-PAI as absence (≤ 1) versus presence (≥ 2) of periapical radiolucency confirmed the CBCT-strict finding.

In a cohort weighted toward large pre-operative lesions (65% at CBCT-PAI ≥ 4), nonsurgical retreatment with a calcium silicate sealer produced outcomes at the upper end of the pooled retreatment literature under both PAI- and CBCT-based assessment at 12 to 24 months. Pre-operative lesion size was the dominant predictor of complete healing (CBCT-strict), while tooth type was the only independent predictor of CBCT-loose success.

This study was registered on ClinicalTrials.gov (identifier NCT05714384).