Prevalence of Pre-Eruptive Intracoronal Resorption (PEIR) and Proposal of a Novel Classification: Retrospective Study with the Aid of Cone Beam Computed Tomography (CBCT)

<b>Background/Objectives</b>: Pre-eruptive intracoronal resorption (PEIR) in impacted or unerupted teeth often remains undiagnosed. The aim of this study was to investigate the prevalence of PEIR with the aid of cone beam computed tomography (CBCT) and propose a new three-dimensional (3D) classification for the analysis of the lesions. <b>Methods</b>: A total of 164 unerupted teeth diagnosed in CBCT scans, derived from an equivalent number of patients, were examined for the presence of PEIR, tooth type, angulation and position. A novel 3D classification system was proposed and all PEIR lesions were further classified. The classification system was used to stage PEIR lesions according to their extend from the enamel level apically, the circumferential spread and their proximity to the pulp chamber. Descriptive statistics were used to assess the prevalence and type of resorption. The association between PEIR, demographics, tooth type, position and angulation were studied. The estimation of the multivariate relationship between PEIR, patient's demographics and tooth characteristics was conducted with the multiple binary logistic regression model. <b>Results</b>: The prevalence of PEIR was 33.5%, affecting mostly maxillary canines, and maxillary and mandibular molars. The prevalence of PEIR in ages over 45 years was significantly higher (<i>p</i> < 0.001). The presence of PEIR was significantly associated with buccal position (<i>p</i> = 0.002) and buccal angulation (<i>p</i> = 0.016) of the tooth. <b>Conclusions</b>: Due to the high prevalence of PEIR, CBCT may improve detection and 3D characterization when imaging is already clinically indicated, and influence treatment planning in selected cases.