Design of a maxillary distraction device for cleft palate patients

Cleft lip and palate (CLP) is the most frequent craniofacial defect in Mexico (1:1000 newborns). CLP patients present severe maxillary retrusion that limits normal oral functions and causes facial deformity. About 50% of these patients require a surgical procedure to advance their maxilla. Distraction osteogenesis (DO) is an effective treatment in terms of results and long term stability, however available internal maxillary distraction devices present inconveniences for the patients as well as for the craniofacial surgery team. Objective: Design a biocompatible inexpensive and mechanically efficient prototype of an internal maxillary distraction device, for maxillary advancement for CLP patients. This device should be easy to place and adjust, advancement vectors should be controllable and it should be comfortable for the patient. Method: Computed tomography (CT) data of an adult patient with a complete unilateral cleft of the palate and a maxillo-mandibular 12 mm discrepancy was obtained. DICOM files were processed to separate the mandible and maxillary segments. A stereolitographic (STL) model was printed and used as a model to determine the size and shape of the device parts. Computer aided design (CAD) software was used to design, ensemble and assign mechanical properties to the different parts, based on the selected materials. Next, we defined the mobile and fixed parts; estimated the forces/vectors and performed a finite element analysis (FEA) to evaluate the mechanical behavior of the appliance. Results: The virtual prototype complies with requirements for an efficient internal maxillary distraction device and a prototype will be made by a computer aided manufacturing (CAM) process and mounted on a STL model to be tested. Conclusions: The integration of clinical knowledge with novel technology (CT, STL, CAD, FEA, and CAM) is very useful for the development of medical or dental appliances. Our prototype will need to be clinically tested in the future.