prediction accuracy of dolphin 3d in bimax surgery for class iii

Conditions: Orthognathic Surgery

Summary: patients with class iii dentofacial deformity who are in need of surgical correction are now able to see the potential changes to their faces before the actual operation. dolphin 3d is one of the few software packages that is used for orthognathic planning and prediction of soft tissue changes. the direct effect of the prediction procedure over patient's and surgeon decisions makes it important to guarantee a high level of accuracy of operational results prediction. this study is designed to investigate the accuracy of dolphin 3d software for the prediction of postoperative soft tissue changes following specific surgical procedure which is the combined maxillary advancement and mandibular setback, commonly used for correction of class iii facial deformity cases. the study data will be collecting retrospectively. the difference between the pre-operative soft tissue prediction and the 6-month postoperative results will be analysed. the results of this study will help to determine whether this software package is accurate enough to be considered as a surgical assistance tool helping both surgeons and patients in treatment planning and decision-making procedure respectively.

the study will employ the pre-existing cbct images routinely captured for orthognathic surgery patients in glasgow dental hospital and school. the cbct scans of class iii patients who undergone maxillary advancement with minimal or without impaction and mandibular setback will be identified. the preoperative and 6 months postoperative cbct images will be anonymised the surgical planning and soft tissue prediction will be performed on the preoperative images using dolphin3d software. the resultant soft tissue 3d model will be superimposed on the actual postoperative soft tissue model. analysis of the difference between the prediction and the actual postoperative will be performed to quantify the difference between them in order to assess the accuracy of the software prediction. the sample will be collected according to the inclusion and exclusion criteria. pre and post operation cbct voxel based super imposition using ondemand 3d. the surgical movement will be quantified using direct slice land-marking . using the pre-operattion cbct to do the surgical mock up and the soft tissue simulation on dolphin 3d. segment the soft tissue of the prediction. soft tissue surface models of the simulation and the actual postoperative images were generated and exported as stls. generic meshes conformation dense correspondence analysis. superimposition of the predicted and the post operative stls. using vr mesh software, the mesh will be segmented into pre-identified anatomical regions. the distance between the corresponding vertices will be displayed as a colour scale in milli-meter and will be analysed in the individual dimension of space (x, y and z) using in-house software and each dimension will be displayed as a colour coded distance map.

Eligibility criteria:
inclusion criteria: 1. patients who have class iii facial deformity to be corrected using bimaxillary orthognathic surgery. 2. no medical problems that might interfere with general anesthesia or interfere with bone and soft tissue healing. exclusion criteria: 1. there are craniofacial anomalies including cleft lip/palate, 2. patient have previous maxillofacial operations or facial scars, 3. correction mandates multi-segment le fort i osteotomies, 4. there are orthodontic appliances in place at the time of t1 records. 5. genioplasty is recommended for deformity correction. 6. there is facial asymmetry.