# Association Between Residual Pericervical and Apical Dentine and Vertical Root Fracture in Endodontically Treated Molars: A Case‐Control Study

## TL;DR

This study finds that excessive removal of dentine during root canal treatment increases the risk of vertical root fractures in molars.

## Contribution

The study identifies residual dentine levels as a novel risk factor for vertical root fractures in endodontically treated molars.

## Key findings

- Excessive preparation of pericervical and apical dentine is strongly linked to vertical root fractures.
- Residual apical dentine, tooth type, re-treatment history, and time since treatment are significant predictors of VRF.
- A diagnostic model with high accuracy (AUC 0.940) helps differentiate VRF from non-VRF teeth.

## Abstract

Vertical root fracture (VRF) in endodontically treated molars (ETMs) is a multifactorial condition. However, the relationship between residual pericervical and apical dentine in ETMs and VRF has yet to be fully assessed. This study aimed to investigate the association between residual pericervical and apical dentine and VRF in ETMs.

ETMs with VRFs (44 cases) and those without VRFs (92 controls) were included. Residual dentine at pericervical level and apical terminus of root canal filling (RCF) were assessed based on the ratio between the mesiodistal widths of the RCF and root on periapical radiographs. The ratio was converted into four categories: “intact canal”, “minimum preparation”, “traditional preparation”, and “excessive preparation” based on calculated cut‐off values. History of root canal re‐treatment (reRCT), and time from the primary root canal treatment (pRCT) were assessed as cumulative factors. Descriptive and logistic regression analyses were used to identify risk factors for VRF. Receiver operating characteristic curves were constructed, and the corresponding area under the curve (AUC) was used to determine the model as a diagnostic tool.

“Excessive” category at both pericervical and apical dentine was more frequently observed in teeth with VRF (81.8%; 36/44, 61.4%; 27/44) than in the control group (65.2%; 60/92, 10.9%; 10/92). Residual apical dentine, tooth type, history of reRCT, and time from pRCT ≥ 15 years were significantly associated with VRF in the multiple binary logistic regression analyses (p < 0.05).

Successful pRCT with minimum canal preparation, particularly at the apical level, is essential to minimize the likelihood of VRF. In ETMs with an isolated periodontal probing depth ≥ 5 mm, assessing residual apical dentine, tooth type, reRCT history, and time since pRCT can effectively differentiate VRF from non‐VRF teeth (AUC, 0.940; p < 0.001), offering valuable diagnostic guidance.