抄録
Simultaneous bimaxillary orthognathic surgery, which can alter an occlusal plane, is employed for correction of varying maxillomandibular dentofacial deformities. Since positioning of the maxillary segment is inherently considerable to improve both facial esthetics and occlusion, a systematized and ensured procedure is needed to obtain stable results.
The authors describe here the bimaxillary surgical procedures with special reference to a newly devised “Two-Step positioning” of the maxillary segment utilizing face bow transfer and an occlusal plane indicator.
The Two-Step positioning technique is summarized as follows:
1) An altered occlusal plane of the maxilla in model surgery is recorded in a Quick mount face bow (Whip-mix Co.). Beforehand the dental arch impression made with self-curing resin and small hooks at bilateral premolars is attached to the bite fork, which securely holds the mobilized maxillary segment on the bite fork during surgery.
2) Step 1: After mobilizing the mandible and maxillary segment, the maxillary occlusal plane is transfered to the patient by means of face bow transfer. The maxillary segment is immobilized with two low profile miniplates (Leibinger Co.).
3) Step: The occlusal plane indicator having an upper dental arch impression is applied to the dental arch, which enables easy assessment of the occlusal plane three-dimensionally. In case indicating additional correction of the plane, loosening some screws of the miniplate allows versatility in repositioning of the segment.
This technique has been applied to 30 cases without incidence, and it has been our experience that positioning of the maxillary segment is ensured and the surgical procedures are systematized with this technique.
