Radiographic assessment of periapical healing following fractured instrument removal: a retrospective cohort study with one-year follow-up using the periapical index and the probability index

Abstract

This retrospective cohort study evaluated periapical healing outcomes over a one-year follow-up period following the retrieval of fractured instruments (FIs) and analyzed the diagnostic classification consistency between the Periapical Index (PAI) and the Probability Index (PRI). Additionally, the potential influence of selected clinical and anatomical variables on radiographic healing outcomes was exploratorily investigated. A total of 38 consecutive cases managed between 2022 and 2024 were included based on specific eligibility criteria. Historical clinical records were reviewed, and standardized baseline (T0) and one-year postoperative (T1) periapical radiographs were evaluated. Radiographic periapical status was dichotomized into success (scores 1–2) or failure (scores 3–5) categories for both index systems. At the one-year follow-up, periapical healing success rates were 84.21% via the PAI and 81.58% via PRI, with McNemar’s test indicating significant improvement for both scoring systems ( p < 0.001 for PAI and p = 0.008 for PRI). A substantial agreement was observed between the PAI and PRI assessments at T1 (kappa = 0.676, p < 0.001). Bivariate exploratory analyses suggested that root canal treatment quality ( p = 0.001) and obturation length ( p < 0.05) were significantly associated with healing outcomes across both indices, while the apical location of the FI fragment appeared to be associated with higher radiographic failure rates within the PAI assessment ( p = 0.035). Within the limitations of this retrospective data, favorable periapical healing outcomes may be expected following FI removal. Healing dynamics appear to be substantially related to the technical quality of the root canal filling and proper obturation length. Furthermore, the substantial agreement between the PAI and PRI scoring systems indicates that both indices could potentially provide a consistent framework for monitoring radiographic outcomes.

The authors' abstract, as published at the source. BMC Oral Health, 2026 · DOI ↗