This study aimed to evaluate the influence of mini-screw position and number in mini-screw-assisted rapid palatal expansion (MARPE) expanders in a patient with cleft lip and palate (CLP). A cone-beam computed tomography scan of a patient aged 17 years with bilateral complete CLP was used to construct six finite element models with MARPE expanders: three bone-borne and three tooth-bone-borne configurations, varying by mini-screw number (two or three) and position (anterior or posterior). Each expander was transversely activated to achieve 1.0 mm expansion. Equivalent elastic strain (µƐ) distributions were assessed in the maxillary palatal bone, dentoalveolar bone, and anchoring teeth. Deformation patterns in the palate and alveolar ridges (4,000 µƐ) were influenced by both mini-screw number and, more significantly, position. The presence of at least one mini-screw was critical for generating strain in the anterior palate. Expander arms produced notable strain at the insertion sites of banded anchoring teeth (100 µƐ). Mini-screw position appeared more influential than quantity in determining strain distribution. An anterior mini-screw was essential for inducing anterior palatal stress, while expander arms, regardless of mini-screw configuration, contributed to stress distribution across anchoring teeth and posterior alveolar ridges.
Patiño et al. (Wed,) studied this question.