Localization of the centre of resistance in different osteotomy pattern for maxillary complex with cleft lip and palate

Abstract

Objective To explore the location of the centre of resistance for the maxillary complex in cleft lip and palate by the use of finite element analysis. Methods Combining spiral CT scanning technology with the three-dimensional finite element method, a three-dimensional FEM model of LeFort Ⅰ , Ⅱ , and Ⅲ complex and soft tissue in cleft lip and palate was developed for analysis. Anteriorly and inferiorly directed forces of 9.8N were applied at five different levels parallel to the functional occlusal plane and four different levels perpendicular to the functional occlusal plane, respectively.For each loading condition, horizontal and vertical displacements of different anatomic points in the complex and on the maxillary dentition were analysed. Location of the centre of resistance in different osteotomy complex were studied. Results The resistant center of the LeFort Ⅱ complex in cleft lip and palate was located on intersection between basis nasi and medium of apertura piriforms vertically,apex of the canine and posterior point of the first bicuspid horizontally. The resistant center of the LeFort Ⅲ complex in cleft lip and palate was located on intersection between anterior of the nasion and medium of apertura piriforms vertically, posterior point of the first molar and first bicuspid horizontally. Conclusion Knowledge of the resistant center of different osteotomy complex could establish a basis for biomechanical studies of craniofacial complex distraction osteogenesis in cleft lip and palate. Key words: Cleft lip and palate; Biomechanics; Resistant center; Maxillary complex