[Study of three-dimensional anatomical relationship between infrazygomatic crest and maxillary sinus for mini-screw insertion].

Purpose: To measure the thickness of the infrazygomatic(IZ) crest above the maxillary first molar and analyze its relationship with maxillary sinus as to derive clinical implications and provide guidance for placements of orthodontic mini-screw.

Methods: Thirty seven cone-beam CT(CBCT) images of infrazygomatic crest sites were collected from data of 19 adult inter-treatment orthodontic patients. Based on the relationship of maxillary sinus floor and mesiobuccal root of the maxillary first molar, the subjects were divided into high sinus floor group (n=13) and low sinus floor group (n=24).

[Maxillary protraction with and without maxillary expansion on unilateral cleft lip and palate model: a finite element analysis].

Purpose: The aim of this finite element study was to investigate biomechanical effects of maxillary protraction with and without maxillary expansion on unilateral cleft lip and palate(UCLP)model before and after alveolar bone graft (ABG).

Methods: Orthopedic force (30° downward and forward to the occlusal plane, 5N/side) with expansion and without expansion were loaded on models before ABG, and after ABG respectively. Initial displacement and sutural stress were analyzed by using ANSYS12.