Maxillary expansion in bilateral complete cleft lip and palate (BCLP) poses unique biomechanical challenges due to disrupted anatomy and scarred sutures. This finite element study compared three expander types—conventional Hyrax, pre-positioned Hyrax, and fan-shaped—in a patient-specific BCLP model derived from CBCT data. We evaluated 3D dentoalveolar displacement, craniofacial suture strain, and periodontal ligament (PDL) stress. The fan-shaped expander achieved greater anterior expansion and vertical control but induced higher von Mises stress and buccal tipping, raising concerns over periodontal safety. In contrast, conventional and pre-positioned Hyrax expanders produced more uniform force distribution and better posterior anchorage control. Skeletal displacement patterns were comparable across models. The findings suggest that fan-shaped expanders may be beneficial for cases with severe anterior constriction but require caution due to stress concentration risks, while Hyrax variants offer biomechanically safer alternatives for moderate expansion needs. This study provides novel, evidence-based insight into expander selection in complex cleft patients and emphasizes the importance of individualized, morphology-driven appliance design.

Bilateral cleft lip and palate

Hyrax expander

Fan-shaped expander

Finite element analysis

Periodontal ligament stress

Orthodontic biomechanics

© 2025 The Authors. Published by Elsevier Ltd on behalf of European Association for Cranio-Maxillo-Facial Surgery.