A reversed approach for simultaneous mandibular symphyseal split osteotomy and genioplasty

Performing a mandibular symphyseal split and genioplasty simultaneously and accurately is a technical challenge for the surgeon. The aim of this study was to validate a reversed approach for simultaneous symphyseal split and genioplasty. A cutting guide and a repositioning guide were designed and printed three-dimensionally in titanium. The symphyseal split and genioplasty were performed successfully. The accuracy of the technique appears to be appropriate for clinical application.

A new approach of splint-less orthognathic surgery using a personalized orthognathic surgical guide system: A preliminary study

The purpose of this study was to evaluate a personalized orthognathic surgical guide (POSG) system for bimaxillary surgery without the use of surgical splint. Ten patients with dentofacial deformities were enrolled. Surgeries were planned with the computer-aided surgical simulation method. The POSG system was designed for both maxillary and mandibular surgery. Each consisted of cutting guides and three-dimensionally (3D) printed custom titanium plates to guide the osteotomy and repositioning the bony segments without the use of the surgical splints. Finally, the outcome evaluation was completed by comparing planned outcomes with postoperative outcomes. All operations were successfully completed using the POSG system. The largest root-mean-square deviations were 0.74mm and 1.93° for the maxillary dental arch, 1.10mm and 2.82° for the mandibular arch, 0.83mm and 2.59° for the mandibular body, and 0.98mm and 2.45° for the proximal segments. The results of the study indicated that our POSG system is capable of accurately and effectively transferring the surgical plan without the use of surgical splint. A significant advantage is that the repositioning of the bony segments is independent to the mandibular autorotation, thus eliminates the potential problems associated with the surgical splint.

A new design of CAD/CAM surgical template system for two-piece narrowing genioplasty

The purpose of this study was to develop and validate a new chin template system for a two-piece narrowing genioplasty. Nine patients with wide chin deformities were enrolled. Surgeries were planned with the computer-aided surgical simulation (CASS) planning method. Surgical splints and chin templates were designed in a computer and fabricated using a three-dimensional printing technique. The chin template system included a cutting guide and a repositioning guide for a two-piece narrowing genioplasty. These guides were also designed to avoid the mental foramen area and inferior alveolar nerve loops during the osteotomy, for nerve protection. After surgery, the outcome evaluation was completed by first superimposing the postoperative computed tomography model onto the planned model, and then measuring the differences between the planned and actual outcomes. All surgeries were completed successfully using the chin template system. No inferior alveolar nerve damage was seen in this study. With the use of the chin templates, the largest linear root mean square deviation (RMSD) between the planned and the postoperative chin segments was 0.7mm and the largest angular RMSD was 4.5°. The results showed that the chin template system provides a reliable method of transfer for two-piece osseous narrowing genioplasty planning.

Computer-assisted surgical planning and intraoperative navigation in the treatment of condylar osteochondroma

Mandibular condylar osteochondroma (OC) results in asymmetric prognathism with facial morphology and functional disturbances. The aim of this study was to explore the feasibility of computer-assisted surgical planning combined with intraoperative navigation in the treatment of condylar OC. Five patients with mandibular condylar OC were enrolled in this study. Surgical planning and simulation was performed based on a computed tomography reconstruction model using SurgiCase software. Under the guidance of navigation, a condylar OC resection and conservative condylectomy was carried out via intraoral approach. Simultaneous orthognathic surgery was used to correct the facial asymmetry and malocclusion. All patients healed uneventfully. No facial nerve injury or salivary fistula occurred. Facial symmetry and morphology were greatly improved and stable occlusion was obtained in all cases. Good matching between preoperative planning and postoperative results was achieved. Patients showed no signs of recurrence or temporomandibular joint ankylosis during follow-up of 12-30 months. Computer-assisted surgical planning and intraoperative navigation is a valuable option in the treatment of mandibular condylar OC.

Endoscope-assisted conservative condylectomy in the treatment of condylar osteochondroma through an intraoral approach

Mandibular condylar osteochondroma (OC) can result in morphological and functional disturbances, including facial asymmetry and temporomandibular joint (TMJ) dysfunction. The aim of this study was to explore the feasibility of endoscope-assisted tumour resection and conservative condylectomy via an intraoral approach. Seven patients with condylar OC were enrolled in this study. Endoscope-assisted tumour resection and conservative condylectomy were achieved intraorally, and no conventional extraoral incision was needed. Direct vision of the magnified and illuminated operative field was realized with the assistance of an endoscope. No facial nerve injury or salivary fistula occurred in any patient. Stable occlusion was realized through postoperative orthodontic treatment. The patients showed no signs of tumour recurrence or TMJ ankylosis during follow-up (range 18-43 months). Endoscope-assisted condylar OC resection and conservative condylectomy via intraoral approach offers great advantages with no significant complications compared with conventional extraoral incisions. The endoscope provides us with a valuable treatment option for this potentially complicated procedure.

Computer-assisted three-dimensional surgical planing and simulation. 3D soft tissue planning and prediction

The purpose of this paper is to report a new technique for three-dimensional facial soft-tissue-change prediction after simulated orthognathic surgical planning. A scheme for soft tissue deformation, "Computer-assisted three-dimensional virtual reality soft tissue planning and prediction for orthognathic surgery (CASP)", is presented. The surgical planning was based on three-dimensional reconstructed CT visualization. Soft tissue changes were predicted by two newly devised algorithms: Surface Normal-based Model Deformation Algorithm and Ray Projection-based Model Deformation Algorithm. A three-dimensional color facial texture-mapping technique was also used for generating the color photo-realistic facial model. As a final result, a predicted and simulated patient's color facial model can be visualized from arbitrary viewing points.

Three-dimensional virtual reality surgical planning and simulation workbench for orthognathic surgery

A new integrated computer system, the 3-dimensional (3D) virtual reality surgical planning and simulation workbench for orthognathic surgery (VRSP), is presented. Five major functions are implemented in this system: post-processing and reconstruction of computed tomographic (CT) data, transformation of 3D unique coordinate system geometry, generation of 3D color facial soft tissue models, virtual surgical planning and simulation, and presurgical prediction of soft tissue changes. The basic mensuration functions, such as linear and spatial measurements, are also included. The surgical planning and simulation are based on 3D CT reconstructions, whereas soft tissue prediction is based on an individualized, texture-mapped, color facial soft tissue model. The surgeon "enters" the virtual operatory with virtual reality equipment, "holds" a virtual scalpel, and "operates" on a virtual patient to accomplish actual surgical planning, simulation of the surgical procedure, and prediction of soft tissue changes before surgery. As a final result, a quantitative osteotomy-simulated bone model and predicted color facial model with photorealistic quality can be visualized from any arbitrary viewing point in a personal computer system. This system can be installed in any hospital for daily use.