Virtual Surgical Planning and Minimal Fixation in Jaw Bone Reconstruction
Virtual surgical planning and 3D rapid prototyping are relatively new technologies that allow accurate intraoperative execution of tumor resection, flap osteotomy and adaptation because these steps are dependent largely on surgeons experience, intraoperative judgment, and technical speed. These new technologies also permit a reduction in the learning curve associated with mandibular reconstruction. This method holds potential for enhanced levels of precision and acceleration of a time-consuming intraoperative step.
In case of advanced head and cancer, primary reconstruction of mandibular defect without simultaneous bone grafting is sometimes mandated due to the oncologic basis. However, several complications such as fatigue fracture of reconstruction plate, screw loosening , screw fracture and plate exposure are emerging after a certain period. To avoid such complications that are related to plate only bridging, primary or early secondary bone grafting is recommended as the treatment of choice. Previous studies show that segmental fibular vascularized bone grafts demonstrate good bony union and suggest that they undergo hypertrophy if the bone is weight-loaded. In contrast, lack of weight bearing due to stress shielding by a large plate that has a higher modulus of elasticity results in osteoporosis and decreased bone strength. Large stress-shielding plates may cause demineralization and decrease in bone strength. The ability of bone to undergo hypertrophy is a potential advantage of vascularized autografts. Compared with nonvascularized grafts, vascularized bone grafts have superior blood flow and osteocyte survival. Single large plates are also used for free flap stabilization; they can be appropriately shaped and applied to mandibles before segmental resection, thereby maintaining occlusal relationships. Furthermore, these plates can be prebent, which can save operative time and maximize geometrical accuracy. Vascularized bone grafts are also fixed and contoured using mandibular plating systems. Plating techniques range from small miniplates to large reconstructive plates, which theoretically shield more stress than the smaller miniplates do. Miniplates have the advantages of ease of application, short fixation time, and ease of selective removal should the need arise. Their small size allows for precise contouring and may lead to a superior aesthetic result.