Accuracy of combined maxillary and mandibular repositioning and of soft tissue prediction in relation to maxillary antero-superior repositioning combined with mandibular set back A computerized cephalometric evaluation of the immediate postsurgical outcome using the TIOPS planning system

Abstract

Aim: The purpose of the present study was to evaluate the immediate postsurgical outcome of planned and predicted hard and soft tissue positional changes in relation to maxillary antero-superior repositioning combined with mandibular set back using the computerized, cephalometric, orthognathic surgical planning system (TIOPS).

Material and methods: Out of 100 prospectively and consecutively treated patients, 52 patients manifested dentofacial deformities requiring bimaxillary orthognathic surgery with maxillary antero-superior repositioning combined with mandibular set back and so were included. All patients were managed with rigid internal fixation (RIF) and without intermaxillary fixation (IMF). Preoperative cephalograms were analyzed and treatment plans and prediction tracings produced by computerized surgical interactive simulation. The planned horizontal and vertical hard tissue positional changes were transferred to model surgery on a three-dimensional articulator system (SAM) and finally to surgery. Five to six weeks after surgery, the actually obtained hard and soft tissue profile changes were cephalometricly assessed.

Results: The mean accuracy of the planned and predicted hard and soft tissue outcome was relatively high varying from 0.0mm to 0.5mm from one cephalometric reference point to another. At the cephalometric reference points where significant differences between planned/predicted, and actually obtained hard and soft tissue positional changes were demonstrated, these significant inaccuracies were, except for the predicted horizontal position of the lower lip, relatively small, varying from 0.2mm to 1.1mm. However, the variability of the predicted hard and soft tissue individual outcome was relatively high.

Conclusion: The current study demonstrates from a mean point of view relatively high predictability of the immediate postsurgical hard and soft tissue outcome. However, as the variability of the predicted individual outcome seems to be relatively high, caution should be taken when presenting the planned and predicted hard and soft tissue positional changes to the individual patient, preoperatively.