It is very important to reposition and to keep the occlusal plane in harmonious relation to TMJ and the skull in two jaw surgery. In addition, the surgery should be performed as accurately as the presurgical planning.
However, it is not always easy to satisfy the above-mentioned items in deformities indicating sagittal, transverse and vertical dysplasia or discrepancy of maxilla and mandible. For this reason, we have performed the method of intra-operative repositioning of the Le Fort I osteotomized maxilla according to the pre-operative planning by using the semi-adjustable articulator SAM or Whip-Mix facebow. We use routinely the simultaneous jaw movement by Le Fort I and sagittal splitting osteotomy for two jaw surgery.
The maxillary position determined by preplanning of the cephalometric prediction tracing and model operation is recorded with the facebow. After the recording, the facebow with the bitefork is removed from the articulator, and is sterilized with gas to be ready for the intraoperative transfer.
The maxilla is adequately mobilized as usual, the vertical dimensions of maxilla are reduced to the same extent as the model operation. The osteotomized maxilla is inserted into the bite fork. Then, the facebow is adjusted to the external auditory canal.
In addition, intermaxillary wiring is performed after the mandible is also inserted into the bitefork. Once the facebow is fixed by the nasion locator, the facebow system is kept rigid and free from distortion.
The characteristics or advantages and the indication of this facebow transfer system are as follows:
1. This system using the Whip-mix or the SAM facebow guarantees precise transfer from the articulator to the patient.
2. It has the possibility of obtaining intra-operatively accurate reproduction of the position of osteotomized maxilla in relation to the skull, the mandibular teeth arch, and the TMJ as preplanned.
3. It has the possibility of keeping the transferred position and stabilizing maxilla with the mini-plates without freehanding.
4. As this system is a “step by step” technical procedure, the laboratory workup is very important.
5. The model operation in this system is for the oral surgeon operation training.
6. The indication of this system seems to be facial asymmetry or long face with mandibular protrusion.
We have performed this facebow transfer system on 14 patients and obtained good results. All patients currently have acceptable results.