Examining facial soft tissue changes following orthognathic class III (bimax) surgeries applying structured light technique for the design and implementation of 3d facial modeling software

Abstract

Background: Improvement of facial beauty is a major reason why patients with dentofacial problems opt for orthognathic surgery. People are eventually judged by their facial appearanceby themselves, their friends & family and even surgeons. With the recent developments in technology, we now have a 3D structure that can build and analyze 3D images before & after surgery and review the extent of changes taken place. Imaging techniques include: structured light photogrammetry, CT scan, 3D cephalometry, CBCT and other methods such as MRI and ultrasound. Structured light photogrammetry Using photography cameras (visible range) – without any harmful radiation – with 3D modeling of the face with high precision. The automatic operationof this procedure reduces human error and yields more accurate final results.Materials and Methods: A ‘before & after’ clinical trial was conducted. Twenty four patients (17 females & 7 males) who were candidates of orthognathic Bimax surgery as a result of Class III malocclusion and who had attended Shariati Hospital’s Maxillofacial Clinic were included in the study. The patients’ surgical planning was the ‘Lefort I osteotomy + Mandibularbilateral sagittal split osteotomy (BSSO). Photography was done through the photogrammetry method.Results: 3D modeling of the patients’ faces was done before & after surgery by photogrammetry. Changes following surgery were determined and their formula was calculated.Conclusions: The resultant mathematical model can be used to build software for the 3D prediction of soft tissue changes following orthognathic surgery. However, it is better to evaluatethe validity of the software and mathematical model in a separate study to apply the necessary changes if need be. Keywords: orthognathic surgery, photography, photogrammetry, 3D face modeling