Abstract
Internal maxillary distraction with the Le Fort I osteotomy is a technique that can provide simultaneous skeletal advancement and gradual expansion of the soft tissue. For calibrating the vectors of the internal distractors and transferring the desired vectors to the patient, surgical guides may be fabricated before surgery on a stereolithographic model. The anterior nasal spine may be used as a critical anatomical landmark for applying this type of surgical guide.
Maxillary hypoplasia is a deficiency that usually manifests in more than one plane, requiring three-dimensional (3D) correction of the deformity. This skeletal problem can be treated with a Le Fort I osteotomy, followed by maxillary repositioning and stabilization with internal plate fixation in patients with permanent dentition. Maxillary distraction osteogenesis is indicated in severe angle class III malocclusions and severe maxillary hypoplasia among some cleft patients and those with other craniofacial deformities. Distraction osteogenesis has some advantages, such as easy advancement of the maxilla, being easy and safe for large advancements, and achieving stable results.
During Le Fort I distraction osteogenesis, placement of the distractor in the correct position and then disconnecting it before the osteotomy is a difficult procedure and lengthens the operation time. A surgical guide placed on the anterior nasal spine (ANS) may be useful for carrying the correct position obtained on the 3D model to the patient’s maxilla. At the same time, it may simplify the technical difficulties and may shorten the operation time. We present a transparent acrylic surgical guide placed on the ANS for these purposes in Le Fort I distraction osteogenesis.
Technique
Planning of the operation was done on the patient’s 3D model and the distractors were chosen bilaterally for Le Fort I distraction. After marking the osteotomy line, the distractors were placed on the model and then the distractor plates were contoured to fit the model and fixed with screws. Next, the distractors were disconnected and the transparent acrylic surgical guide was prepared on the 3D model ( Fig. 1 ). To prepare the surgical guide, self-curing acrylic resin was attached on both sides of the maxilla and oriented according to anatomical landmarks, such as the ANS. The position of the surgical guide was secured on the model according to reference points, such as the ANS and the contours of the lateral maxillary wall. The acrylic plate fitted tightly to the nasal spine like a mortise and tenon system ( Fig. 2 ). After the surgical guide was fitted to the model, the screw holes of the distractor plates were marked and opened on the guide using a bur.
During the operation, the planned position of the distractor was carried to the patient’s maxilla using the transparent acrylic guide and this was easily adapted to the patient’s maxilla with the previously created mortise and tenon system using the ANS. The screw holes that were marked on the acrylic guide were opened before the Le Fort I osteotomy. The osteotomy was performed after opening the holes; the maxillary distractor was then placed in the correct position very easily. After the activation phase of the distraction osteogenesis, planned vectors and directions could be achieved and hence the maxilla was located in the desired position ( Fig. 3 ).
