Volume 14, Number 2, June 2002

Accuracy of Maxillary Positioning During Orthognathic Surgery: Comparison of 2 External Reference Points

Mitsuyoshi Iino,1 Kouta Niitsu,2 Toshikatsu Horiuchi,2 Rintaro Matsushima,2 Yoshiki Hamada,3 Hiroaki Ishii,3 Toshirou Kondoh,3 Kanichi Seto3

1Division of Dentistry and Oral Surgery, Akita University, School of Medicine, Akita, Japan
2Department of Dentistry and Oral Surgery, Saku Central Hospital, Nagano, Japan
3First Department of Oral and Maxillofacial Surgery, Tsurumi University, School of Dental Medicine, Yokohama, Japan.

Objectives: The surgical accuracy of 2 external reference points when repositioning the osteotomised maxilla was analysed.
Patients and Methods: In 31 patients undergoing Le Fort I osteotomy during orthognathic surgery, the intermediate splint and unoperated mandible was used to provide a horizontal maxillary position. In 14 patients, an external reference point marked on the forehead was taken to determine the maxillary vertical dimension (group I). In 17 patients, a miniplate screw placed into the frontal bone was used as an external reference point (group II). Preoperative lateral cephalograms were traced and superimposed onto the postoperative cephalograms to compare the preoperative, postoperative, and predicted position of the maxillary central incisor and the posterior nasal spine of each patient. The differences between predicted and actual changes in the maxillary central incisor and posterior nasal spine were calculated using the Frankfort horizontal plane as a reference.
Results: Statistical analysis showed that an external reference point placed into the bone was a more reliable method of positioning the maxilla in the vertical dimension than a point marked on the skin (p < 0.01).
Conclusion: To improve surgical accuracy, surgeons must strive to reduce positional variance by careful treatment planning and precise surgery.

Key words:
Le Fort, Maxilla, Osteotomy, Surgery

Asian J Oral Maxillofac Surg. 2002;14:61-69.
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