Three-dimensional modeling system for unilateral mandibular bone distraction: A clinical case

Abstract

Facial hemiatrophies are anomalies of the first branchial arch and affect one in 4000-5000 newborns. Bone distraction is the technique of choice for the treatment of these dysmorphoses. Mandibular osteodistraction requires prior determination of the characteristics of the distraction vector whose three components will serve to activate the distractor. The patient, aged 5 years, presented with a right facial hemiatrophy, Grade IB according to the classification of Pruzansky. Tomodensitometric acquisition was obtained with a CT scanner. Software specifically designed for this application allows segmentation of the anatomical elements by a region-growing algorithm. The 3D representation of each element is added to a 3D scene, in which are placed the built-up landmarks necessary for the surgical simulation after 3D cephalometric analysis. The surgical cleavage plane is oriented according to the surgeon's requirements while preserving the predominant anatomical elements. The software allows performance of rotations and translations of the bone segments rendered independently from the cleavage plane. The distances and angles covered during the virtual movement are measured at its conclusion. The aim of moving the bone segments is to render the mandibular occlusion plane parallel to the reference occlusion plane. The vertical growth of the maxilla is realized by secondary recuperation. The distractor used was of an external multidirectional type allowing elongation of the mandibular ramus and mandibular corpus, closure of the goniac angle, and lateralization or medialization of the ramus. On the 15th day, the mandibular angle was reduced by 10 degrees, which allowed closure of the anterior gap and recentering of the incisive areas by a half-cuspid. The patient presented with a complex bone deficit in the three spatial directions, which allowed the development of software for modeling the distraction. Other clinical cases will be necessary to validate this 3D imaging-based technique.

Microcephalia with mandibular and dental dysplasia in adult Zmpste24‐deficient mice

“…Previous studies from our group (Pendas et al 2002;Varela et al 2005) and others (Bergo et al 2002) have partially characterized the phenotype in two different strains of Zmpste24 mutant mice. The whole aspect of the cranium of Zmpste24-deficient mice accurately studied with simple radiology and μCT displayed features of reduced growth rate with respect to the control littermates, based on maxillary vector growth (see Diemunsch et al 2007), which has an anterior-superior direction in control animals whereas is flattened (more horizontal) in the mutants (F.d.C. et al unpublished data).…”