COMPUTER APPLICATION FOR CREATING MAXILLO-FACIAL PROSTHESES FOR CHILDREN

Abstract

Maxillofacial prosthetics in the case of growing children has experienced different approaches over time, taking into consideration the complexity and the relative unpredictability of the mandible's bone growth. At present, the quantification of the mandibular growth is done by using direct measurements of the 3D model generated by the computed tomography, together with the possibility of highlighting the different growth rates between genders. The surgeries are based on two approaches: the autogenous grafts collected from the rib, which have an unpredictable growth rate or, in more severe cases, the implantation of a total temporomandibular joint prosthesis. The last one mentioned requires numerous adjustments throughout the patient's life, because of the mandibular growth. The purpose of this paper is to present a complete temporomandibular joint prosthesis, provided with a capsule which contains a distractor mechanism that can be adjusted with minimal invasiveness at certain periods of time during the child's growth, without the need of complex surgery. Proximal, both the components of the mandibular part and the fossa follow the anatomical shape of the implantation surroundings and are provided with holes for monocortical screws fixation. The fossa component allow the replication to some extent of anatomical and functional route, crossed by the condylar head during the maximum mouth opening while the movement inside the distractor component is based on a rack-and-pinion assembly, commanded by the pinion rotation (screwing) which ensure a good access and adjustment of the mechanism from outside the body. This mechanism is encapsulated in a biocompatible material and attached through fixation to the upper surface of the mandibular base component, the surface which is generated by the condilectomy plane. Thus, this paper describes a method of conceiving, designing, building and manufacturing of such a total prosthesis with a distractor. The computer route begins with data acquisition, 3D model reconstruction from DICOM files generated by the computer-tomography scan, processing, editing, and filtering by "Remesh" operations, artifact removal and export to STL format of the anatomical model. The design process of prosthetic structures and the establishment for each one their own technological paths is made according to the chosen manufacturing technologies: 3D print, respectively CNC.