Response to the comments on ‘An accurate maxillary superior repositioning technique without intraoperative measurement in bimaxillary orthognathic surgery’

We appreciate the interest in our technique and wish to discuss some aspects raised in the letter.

The straight locking miniplates (SLMs) technique that we developed has the advantages of accurate maxillary repositioning and condylar positioning. In the English language literature based on a similar concept, Schwestka et al. reported condylar position control during maxillary orthognathic surgery using a specialized condylar positioning appliance. In contrast, the SLMs technique requires only widely used locking miniplates and screws and accurate superior repositioning of the maxilla during surgery is achieved at any institution.

Commenting on the SLMs technique, it is noted that Kretschmer et al. using non-locking plates as positioning devices for maxillary repositioning found them to be less precise than Gil’s K-wire in the craniocaudal axis (+0.75 (1.09) mm versus 0.23 mm). This study showed accuracy of the maxillary repositioning at the upper incisor. In our experience, anterior maxillary repositioning is comparatively simple with any technique, but accurate three-dimensional repositioning, especially including impaction of the posterior maxilla, is difficult even for experienced surgeons. Although further study is required, we consider that the SLMs technique can provide accurate repositioning of the maxilla in the hands of skilled and less experienced surgeons.

Although condylar positioning devices (CPDs) are used during bilateral sagittal split osteotomy (BSSO), it is reported that there is no scientific evidence to support the routine use of CPDs and the preoperative condylar position might not be the desired postoperative one. We agree with that opinion, but keeping the vertical dimension in the SLMs technique without maintaining the maxillary position manually is different from condylar positioning in BSSO. During maxillary repositioning, SLMs only secure to the maxilla and mandible to maintain the vertical dimension like the incisor pin of the articulator. Therefore, the SLMs technique also can be used for accurate maxillary repositioning during intraoral vertical ramus osteotomy following Le Fort I osteotomy. The most important point of the SLMs technique is not accurate condylar positioning during BSSO but accurate maxillary repositioning, especially superior repositioning. Most surgeons rely on manually repositioning after BSSO to obtain the best mandibular proximal segment relationship with the condylar fossa, and skilled surgeons feel the degree and direction of stress on the proximal segment and remember the data of the condylar position experienced previously. We consider that the SLMs technique can provide acceptable condylar position for less experienced surgeons who are at more risk of inadequate condylar positioning than skilled surgeons. When interferences between the proximal and distal segments in BSSO for mandibular asymmetry cannot be eliminated by bone removal and condylar positioning using SLMs is difficult, we perform ultrasonic vertical osteotomy of the distal segment for safe elimination of the interference and use the SLMs technique after the passive alignment. In the comment, other disadvantages of the SLMs technique also are described. Without several intraoperative measurements, the operating time with the SLMs technique is almost the same as that using conventional methods. In the case of severe maxillary repositioning, the operating time is shorter than using conventional methods with intraoperative measurement. In our experience, a wider or additional incision is not required for the SLMs technique. Although there may be cases in which the SLMs technique cannot be applied in high Le Fort I osteotomy, we consider that we can perform the SLMs technique after surgeons cut and bend the long locking plate in most cases.

We thank the editor for the opportunity to respond.

Competing interests

None declared.

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Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Response to the comments on ‘An accurate maxillary superior repositioning technique without intraoperative measurement in bimaxillary orthognathic surgery’
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