# Multidisciplinary Planning in Orthognathic Surgery for Prosthetic Patients
## 2 Materials and Methods
### Rehabilitation Protocol  
Occlusal stability in the immediate post-operative period is a fundamental factor in the pre-operative planning of orthognathic surgery. This principle applies both to patients with natural teeth and to partially or totally edentulous patients and it is the main factor guiding the entire treatment [12; 13]. There are multiple factors involved in denture stability: for instance, the anteroposterior relationship of the maxilla and mandible affect the stability of the denture. The stability of class I maxilla-mandibular relationship is generally more than those of class II or III. Appropriate positioning of the jaw requires a clinical assessment of zygomatic regions, paranasal area, and nasolabial angle and it follows the general examination of the facial profile by the surgeon. Spray splints are an excellent fastener and are relatively quick and easy to apply for edentulous patients [6].  
A clear distinction must be made between patients whose vertical dimension can be supported by their dental elements and those whose primary stability is not guaranteed by their natural dental elements [14; 15; 16].  
Patients who could base occlusal stability and vertical dimension on their own elements are those with Kennedy class III and IV; conversely, this condition cannot be obtained by patients with total edentulism, with partial edentulism in the posterior sectors (Kennedy class I and II) and patients with fixed prosthesis.  
Therefore, in this study, we distinguish two groups of patients. This distinction is not only important for the final prosthetic rehabilitation, but it leads the whole therapeutic plan. Indeed, for each edentulous patient, it was necessary to obtain a partial or total prosthesis, depending on the clinical case, and to base on it the primary stability of the occlusal complex in the immediate postoperative period. Instead, for patients with fixed prostheses, it was first necessary to perform temporary acrylic resin prostheses according to the current vertical dimension and, later, after the complete assessment of cephalometric and surgical VTO (Visual Treatment Objective), it was possible to produce new temporary prostheses, based on the occlusal conditions of the patient after surgery. The final prosthetic rehabilitation can be provided after a minimum of 6 months.  
A fundamental aspect of the pre-surgery planning for the edentulous patient is represented by the study of the function of the Temporomandibular Joint (TMJ) [17]. This aspect has been studied in all 17 patients, first clinically and later through instrumental investigations, such as open and closed mouth TMJ CT.  
To limit any post-surgical consequences, the treatment of joint dysfunction is always performed before orthognathic surgery. Once the TMJ disorder has been treated and the temporary prostheses are in place, the patient is ready for surgical treatment. For each patient, models' assembly in the articulator is performed to evaluate the three-dimensional inclination of the upper jaw. After evaluating the relationship between the jaw and the Frankfurt plane, the bi-pupillary line, and the smile line, it is possible to correct these parameters according to the correct cephalometric values, in anticipation of surgical treatment [18]. Once the position of the upper jaw is stable, another cardinal aspect of planning is to determine the correct position of the lower jaw. Two elements guide the achievement of this important task: adherence to the class-I of Angle and occlusal stability. Therefore, it is necessary to individually analyse the different clinical cases in detail to get the most accurate work plan.