TY - THES ID - 135927216 TI - Performance of the Malmgren index for assessing root resorption on 2D versus 3D radiographs AU - Michielsens, Hanne AU - Cadenas de Llano Perula, Maria AU - Willems, Guy AU - Jacobs, Reinhilde AU - Verdonck, Anna AU - Begnoni, Giacomo AU - KU Leuven. Faculteit Geneeskunde. Opleiding Master in de specialistische mondzorg (Leuven) PY - 2023 PB - Leuven KU Leuven. Faculteit Geneeskunde DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:135927216 AB - Objectives: (1) To compare the performance of the Malmgren 2D index on 2D and 3D radiographs (2) to assess the added value of 3D radiographs for examining root resorption. Methods: Patients coming to the unit of Orthodontics of University Hospitals Leuven, Belgium with a 2D panoramic radiograph and a 3D cone beam CT taken at an interval of less than 3 months and presenting root resorption on (at least one) incisor and/or canine, were included. Root resorption was scored twice on all upper and lower incisors and canines by using the Malmgren index in both the 2D and 3D sets by 2 independent observers. A linear mixed model was used for data analysis with ‘root resorption score’ as ordinal outcome and ‘type of measurement’ (2D versus 3D) as explanatory factor. Random intercepts were modelled to deal with clustered data for subject, tooth within subject and observer. Results: 2D and 3D images of 20 subjects (14 females, 6 males; mean age 17.75 years) were analyzed. From the 240 teeth subjected to analysis, 85 could not be evaluated due to poor image quality or open apex. Malmgren scores were systematically higher in 2D, which overestimated root resorption (RR) especially in the transversal plane on all incisors and canines and in the sagittal plane on the maxillary incisors. 2D leads to 28.0-34.8% of false positives and negatives when discriminating between root resorption or not. The early stages of root resorption are often misdiagnosed in 2D while the later stages are more accurate. Conclusions: The original Malmgren index is not suited for 3D images, especially on the axial dimension, where using dichotomized values (resorption yes/no) leads to overestimation of RR. A low-dose CBCT of the upper incisors could detect RR with high diagnostic accuracy in the early stages of orthodontic treatment, especially in patients with dental trauma or familial root resorption history and could eventually aid in taking informed decisions regarding modification or discontinuation of treatment. ER -