Root length changes in the maxillary posterior segment following miniplate-anchored intrusion: A retrospective cone-beam computed tomography study

Objectives: The objective of the study is to evaluate morphological changes and orthodontically induced root resorption (OIRR) across the maxillary posterior segment following miniplate-anchored intrusion using cone- beam computed tomography (CBCT). Material and Methods: This retrospective observational cohort study included 19 patients treated for anterior open bite with miniplate-supported intrusion of the maxillary posterior teeth. Pre-treatment (T0) and post- treatment (T1) CBCT scans were analyzed using in vivo software. Root length measurements of maxillary premolars, first molars, and second molars were measured from the central fossa to the root apex. Interrater reliability was assessed using intraclass correlation coefficients > 0.76. Changes in root length between T0 and T1 were analyzed using paired t -tests (α = 0.05). Results: The greatest resorption was observed in the palatal root of the upper right first premolar (0.99 ± 0.41 mm; p = 0.025). Significant shortening was identified in palatal roots of the upper left second premolar (0.76 ± 0.18 mm; p < 0.001) and upper right second premolar (0.51 ± 0.20 mm; p = 0.0167). In first molars, the palatal and distobuccal roots showed the greatest resorption, reaching 0.98 ± 0.26 mm and 0.96 ± 0.21 mm, respectively ( p ≤ 0.001). Second molars demonstrated small, non-significant increases in root length (0.02–0.49 mm; p > 0.05), consistent with continued root development. Conclusion: Miniplate-anchored intrusion results in limited (<1 mm) and clinically acceptable root resorption in maxillary premolars and first molars, while second molars, likely reflecting a subset with incompletely formed apices, appeared resistant to OIRR.