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3D Analysis of Mandibular and Glenoid Fossa Responses to Bone-Anchored Maxillary Protraction in Patients With UCLP
Jeroen Wagemans1, Ralph Steegman1, Yijin Ren1
1Department of Orthodontics, University Medical Centre Groningen, University of Groningen, Groningen, GZ, the Netherlands.
Introduction:
Bone-anchored maxillary protraction (BAMP) has been increasingly used to correct midface deficiency and Class III malocclusion in patients with unilateral cleft lip and palate (UCLP). However, its three-dimensional (3D) effects on the mandible remain insufficiently explored.
Objectives:
To quantitatively assess 3D mandibular displacement and remodelling, glenoid fossa adaptations, and joint space changes following BAMP treatment in patients with UCLP.
Methods:
A longitudinal cohort of 26 patients with UCLP between ages 11-12 years was evaluated. CBCT scans were obtained before (T0) and after approximately 1.5 years of BAMP therapy (T1). 3D surface models were superimposed using three registration methods: anterior cranial base, mandibular symphysis and condylar head. Joint spaces (superior, anterior, posterior, medial) were measured on CBCT slices.
Results:
The mean age of the cohort at T0 was 11.5 ± 0.5 years (range: 10.8-12.4 years), and at T1 was 13.2 ± 0.6 years (range: 11.3-14.3 years). The average treatment duration was 1.7 ± 0.4 years. Measurement reliability was moderate to good (ICC: 0.72-0.90). Significant posterior glenoid fossa remodelling was observed, characterised by anterior bone apposition and posterior resorption (both 0.95 ± 0.08 mm; p < 0.01). The mandible showed displacement in the vertical (2.11 ± 0.12 mm), posterior (1.06 ± 0.10 mm) and lateral (0.83 ± 0.09 mm) directions (p < 0.01). Remodelling along the posterior ramus showed greater change at the gonion (1.18 ± 0.07 mm) than at the condylar notch (0.52 ± 0.06 mm) (p < 0.01), resulting in a mild reduction in gonial angle. Morphological changes in the condylar head were minimal (< 0.30 mm), and alterations in joint spaces were negligible (< 0.20 mm).
Conclusions:
BAMP therapy was associated with measurable mandibular and glenoid fossa adaptations, particularly in the posterior regions, while maintaining condylar and joint space stability. These findings suggest that BAMP treatment may help influence maxillomandibular growth and improve midfacial deficiency without adversely affecting normal mandibular development.
Clinical Study Registration Number:
201700423/The Netherlands National Trial Register (TC 6559).
