Dr. Fernando Melhem Elias
Abstract. Guidelines for Orthodontic Preparation and Surgical Planning
Modern orthognathic surgery demands an accurate orthodontic-surgical planning in order to get optimal esthetics, function and stability. Once the skeletal and occlusal alterations have been diagnosed, the orthodontist should select the more appropriate orthodontic appliance to promote dental movement, using light forces and eventually skeletal anchorage.
Pre-surgical orthodontics aims to modify dental position in relation to the bone bases, correcting inclinations, rotations and crowding. In addition, upper and lower dental arches should be leveled so that they can be coordinated with each other in one or more segments. At this stage, the surgeon shall inform the orthodontist about all dental movements necessary to perform the osteotomies, especially if the case requires segmentations of the maxilla or mandible. Therefore, the orthodontist will be able to create proper spaces between the teeth roots and level the dental arches in segments.
Once the orthodontic preparation is finished and the surgical planning definitely established, the next step is to create surgical guides to assist in reproducing the desired positions of the jaws to the patient at the time of the surgery. Although traditional methods with such purpose have been successfully used over the years, in some cases they may fail due to inherent limitations, as the inability of dental models surgery to portray the surrounding bony anatomy, making it impossible to predict facial changes and other relevant aspects, as the occurrence of bony gaps and overlaps.
For such reasons, in some centers computer-aided surgical simulation has already replaced the traditional methods and is quickly gaining more and more adepts. This method comprises the creation of a virtual skull, which reproduces both the bony structures and the dentition with a high degree of accuracy. After orienting the virtual skull to the neutral head position, one can perform the simulation of the entire surgery in the computer and the transferring of the planned outcome from computer to the patient using CAD-CAM technology and prototyped surgical guides.
After surgery, the orthodontist will proceed with the maximum intercuspation and orthodontic treatment finishing. The tendency to dental and skeletal relapse can me reduced with stable occlusion. However, long-term follow-up is advisable in order to monitor bone remodeling or resorption, as well changes in dental positions. Certainly, good outcomes in combined orthodontic and orthognathic surgery treatments demand good understanding between orthodontists and surgeons, and are directly related to adequate diagnosis and advanced planning methods.