Orthognathic Surgery Planning on 3-Dimensional Stereolithographic Biomodel

PURPOSE

The success of orthognathic surgery depends on the exact planning based on precise diagnosis. Recent advances in 3-dimensional medical image computing have enabled orthognathic surgery planning on stereolithographic biomodels.

In this case report, the use of 3-dimensional stereolithographic biomodel was presented in the orthognathic surgery of a patient with maxillary retrusion, mandibular prognathism and midline shift.

MATERIALS AND METHODS

A 21-year-old male patient with class III malocclusion was referred to our department with the complaints of facial deformity and chewing difficulty. On physical examination, he showed class III malocclusion, mandibular protrusion, and maxillary retrusion. Stereolithographic biomodel was constructed by medical image processing software (MIMICS, Materialise N.V.). Fabrication of the biomodel was carried out by a Spectrum Z 510 3D Color Printer (Z Corporation, Burlington, MA). Le Fort I and bilateral sagittal split ramus osteotomy were simulated on the stereolithographic biomodel, and 6 mm maxillary advancement, 6 mm mandibular setback, and 3 mm mandibular rotation were simulated according to the cephalometric analysis. Triangular axial gaps between proximal and distal osteotomized mandibular segments which were occurred due to the rotational movement of the distal mandibular segment, were filled with dental modeling wax at both sides of the ramus(a:anterior, p:posterior).

The acrylic templates of the gaps were created to determine the size of the bone grafts that are going to be used to fill in the gaps during operation.

Le Fort I and bilateral sagittal split ramus osteotomy were performed according to preoperative planning. Triangular axial gaps were filled with bone grafts which were prepared by using excess bone cut off from the mandible in accordance with templates.

Rigid internal fixation was accomplished by using three lag screws at each side. One of them also stabilized the bone graft thereby pass through in it.

RESULTS

The postoperative period was smooth. Long-term skeletal relapse were not observed during the follow up period of 2 years.

CONCLUSIONS

Bone graft is a reliable standard method for functional rehabilitation of the mandible but it rather elongates the operation time. Stereolithographic biomodel is a valuable tool to plan the orthognathic surgery and to prepare a template for the construction of the bone graft. This technique facilitates the operation procedure and shortens the duration of the surgery.