Digital workflows part 2: applications of digital technology in orthognathic surgical planning – a case series

For those patients whose orthodontic problems are so severe that neither growth modification nor camouflage offers a solution, surgical realignment of the jaws or repositioning of dentoalveolar segments is often the only possible treatment. Successful management of combined surgical and orthodontic treatment often requires the integration of pre-surgical orthodontic, surgical and post-surgical orthodontic phases of treatment.¹

The developments in three-dimensional (3D) clinical imaging and intra-oral scanning in conjunction with advances in computer-aided design (CAD), computer aided manufacture (CAM) and additive manufacturing have led to a digital workflow revolution in the management of orthognathic cases.²

The management of the joint orthodontic-orthognathic patient is a multi-disciplinary team (MDT) approach. Good collaboration between the orthodontist, surgeon and laboratory technician is critical for a successful clinical outcome.³ Traditionally an ideal occlusion is established based on two-dimensional (2D) cephalometric planning of the maxillary and mandibular segments, and by replicating the surgery using gypsum models mounted onto an articulator using a facebow transfer. An orthognathic wafer is then fabricated on the gypsum models in the laboratory using acrylic. The wafer(s) is an occlusal guide used intra-operatively that enables the surgeon to position the jaw(s) in the corrected position(s) following the osteotomy cuts.⁴ In recent years, the use of digital 3D surgical planning platforms for orthognathic surgery has increased. It is widely accepted that improvements in image acquisition, software capabilities, PC processing power and accuracy in 3D printing have led to precise virtual surgical simulations that are valuable in surgical planning, assessment of surgical outcome and patient communication. The 3D printing of orthognathic wafers, osteotomy cutting guides, repositioning jigs, customised fixation plates and anatomical models allows a virtual surgical plan to be transferred from the workstation into the operating theatre. Although 3D-virtual surgical planning (3D-VSP) requires a relatively high level of investment when compared to traditional planning methods, it offers clear advantages. These include the potential to improve reproducibility, clinical and laboratory efficiency, and surgical precision.^{3, 5, 6} The benefits and drawbacks of the use of digital technology in the joint orthodontic/orthognathic approach are listed in Table 1.