Outcome and associated predictors for non-surgical healing of large cyst-like periapical lesions: A CBCT-based prospective cohort study

<strong>Aim:</strong> The aim of this cone-beam computed tomography (CBCT) based study was to evaluate the outcome of non-surgical root canal treatment (RCT) performed for the management of large cyst like periapical lesions (LCPL) and to identify the predictive factors affecting healing. <strong>Methodology: </strong>54 subjects (77 permanent maxillary anterior teeth) with LCPL (&gt;10mm) of endodontic origin were included. A single operator performed standardised multi-visit RCT. Patients were clinically and radiographically examined at 6,12 months and a CBCT scan was taken at 24 months. Two independent blinded evaluators measured the pre and postoperative volume of periapical lesions on CBCT scans using ITK snap software. The outcome was assessed as a percentage change in lesion volume and dichotomized as success (resolved/reduced) or failure (unchanged/enlarged). Ten pre-operative (gender; age; intraoral draining sinus, soft tissue swelling, tooth discoloration, pulp canal obliteration, open apex, root resorption, cortical bone defect and lesion volume) and four intraoperative (apical extent and density of root filling; number of treatment visits and type of root filling) predictive factors were observed. Bivariate and stepwise multivariable linear regression analysis was performed to identify independent predictors affecting treatment outcomes. The significance level was set at 5%. <strong>Results: </strong>A recall rate of 88% was achieved<strong>. </strong>The success rate of RCT was 82.2% (8.9% resolved, 73.3% reduced). Median lesion volume reduction was 75% (IQR 61%-93%). No pre or intra-operative factors were related to treatment failure. However, presence of preoperative cortical bone defect (palatal versus no cortical defect, β= -51.5; 95% CI: -86.9 to -16, p = 0.006) and apical extent of obturation (long versus flush, β= -27.2; 95% CI: -53.8 to -0.6, p = 0.04) were negatively associated with reduction in lesion volume (%). <strong>Conclusion:</strong> LCPL may be successfully managed with RCT. Preoperative cortical bone defect and apical extent of obturation may negatively influence osseous healing.