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Orthognathic surgery: Tackling deceptive complexity

  • Our jaw is a key evolutionary feature of what makes us human.
  • Orthognathic (jaw) surgery is a relatively new field of science.
  • It is a highly collaborative field – combining orthodontics and maxillofacial surgery.
  • There have been some dramatic developments in its short history.
  • AI and computer-aided surgical simulation is shaping its future.

Outside of our brain, few physical characteristics of homo sapiens differ from our ancestors and fellow large apes more than our jaw. Beyond its obvious key functions of eating and breathing, the jaw is a critical component in our ability to communicate through speech. It also looks different – it is narrower than in other apes, plus humans have a chin. The jaw is also an essential part of the aesthetics of our face – it is one of the most observable parts of our bodies. Given the jaw’s evolutionary significance in defining our human identity, it may come as a surprise that the branch of medicine dedicated to its correction — orthognathic surgery – is relatively new. One senior dental academic is helping raise its profile and emphasise the key role of collaboration in its continued development.

Dr R Scott Conley is an associate professor in the Department of Orthodontics and Oral Facial Genetics at the Indiana University School of Dentistry. For the past 25 years, he has helped lead dental and medical schools on collaborations that are characteristic of orthognathic surgery teams. During that time, he has seen remarkable developments in the field and has become one of its most enthusiastic champions. For Conley, it’s time orthognathic surgery stepped into the light.

The jaw’s deceptive complexity

One of the defining characteristics of orthognathic surgery – derived from the Greek words ‘ortho’, meaning straight or correct, and ‘gnathos’, meaning jaw – is that it incorporates separate but associated branches of medicine, mainly oral and maxillofacial surgery, and orthodontics. Part of the reason for this collaborative input is that the jaw is a deceptively complex part of our body. It may seem rather straightforward – essentially the maxilla, or upper jaw, mandible, or lower jaw, the temporomandibular joints (TMJ), which connect the mandible to the skull, the teeth, and masticatory muscles – but, given its critical function, outside of teeth extraction, medicine has historically avoided tampering too much with it.

For Conley, it’s time orthognathic surgery stepped into the light.

It wasn’t until the early part of the 20th century that surgeons felt confident enough to experiment with procedures. As Conley points out, before antibiotics, oral bacteria presented a high risk of post-operative infections, and given the jaw’s complexity, modern anaesthesia and pain management were necessary to make such difficult operations possible. There was also the ever-present danger that misjudgement could leave a patient unable to speak or eat. As the field advanced during the 20th century, orthodontists and maxillofacial surgeons have collaborated to develop the necessary techniques and procedures to ensure effective correction with minimal interruption to jaw function.

Orthodontists and maxillofacial surgeons have collaborated to develop the necessary techniques and procedures to ensure effective correction with minimal interruption to jaw function.

Collaborative pioneers

Among the pioneers and key developments in orthognathic surgery are Dr Richard Trauner and Dr Hugo Obwegeser. Together, they perfected the sagittal split ramus osteotomy (SSRO), a now common surgical procedure to reposition the mandible in a controlled and precise manner and correct various types of jaw discrepancies. Mikako Umemori contributed significantly to developing temporary anchorage devices (TADs), including titanium screws and plates, which minimise invasiveness and improve outcomes. Dr H David Hall, an oral and maxillofacial surgeon, is credited with developing the condylotomy, which helps alleviate pain, restore normal jaw function, and improve joint stability for patients with TMJ disorders.

Conley points to the importance of continued collaboration within the field in defining what is called the ‘envelope of discrepancy’, which guides orthodontists and surgeons in determining the limits of safe and effective orthodontic and surgical movements when correcting jaw discrepancies. Understanding the envelope of discrepancy allows surgical teams to assess the feasibility and predictability of treatment outcomes, helping them make informed decisions and establish realistic treatment goals.

New advanced technology has revolutionised orthognathic surgery.

Predicting treatment outcomes

One of the most important developments in this collaborative treatment planning process has come from significant leaps in imaging technology. For years, orthognathic surgery would require combining detailed dental records, multiple x-rays, and building physical models of a patient’s jaw prior to any major procedure. Today, techniques such as cone-beam computed tomography (CBCT) and computer-aided surgical simulation provide highly detailed 3D images, allowing orthodontists and surgeons to simulate various surgical movements and analyse their effects on the facial appearance and occlusion before lifting a scalpel. Notably, they can easily share data to allow the input of other specialists in real-time to ensure a successful outcome.

Part of the reason for this collaborative input is that the jaw is a deceptively complex part of our body.

Computer technicians are now among those specialists and part of the interdisciplinary collaboration defining the development of orthognathic surgery. As the technology advances, the field will grow even further. Specialists in artificial intelligence, machine learning, and deep learning are already looking for ways to take orthognathic surgery to a virtual level of collaboration, crunching vast tracts of data to create AI-generated surgical approaches based on proven optimal outcomes.

New technology makes it easier for a good surgeon to become a great surgeon and the ability to see the patient in new and more accurate ways.

Compared to other fields within medicine, orthognathic surgery may be relatively new, but its evolution has been quick and dramatic, energised by its collaborative nature. For Conley, its future is bright and exciting; it must be – after all, the jaw is too important a part of our own evolution.

What in your opinion was the most significant development in the history of orthognathic surgery, and why?

There are really two major developments. The first was the development of the bilateral sagittal split ramus osteotomy by Drs Obwegeser and Trauner demonstrating the ability to move the mandible both anteriorly and posteriorly (forward and backwards). The second was the work by Dr William Bell, an oral surgeon in Dallas, Texas, who showed the maxilla could safely be moved in all three planes of space. Prior to his work, most jaw surgery was only done in the mandible. The occlusion (bite) would be correct, but the facial aesthetics could be compromised. Once both jaws could be moved, not only could ideal occlusion be achieved, but facial aesthetics could be optimised at the same time.

What has been the most significant recent development, and why?

For orthognathic surgery teams grounded in the fundamental principles, the ability to use new advanced technology (digital intraoral (dental) scans, digital radiology with CBCT, and now computer-aided surgical simulation) has revolutionised our field. What once took 8–12 hours to plan can now be done in far less time with equal or greater precision. More patients can be treated due to the increased efficiency of the technology. While not a substitute for surgical skill, this new technology makes it easier for a good surgeon to become a great surgeon and the ability to see the patient in new and more accurate ways.

What is the biggest challenge facing the field of orthognathic surgery?

Collaboration between both the providers themselves and the separate insurance authorisation process are two big challenges today. We have all been told that insurance does not and will never dictate treatment. Unfortunately, this is simply not true. Each insurance company has a process to determine what procedures will and will not be covered. While the insurance industry does work with both professions to establish criteria for what procedures will be covered benefits, and which patients will be approved, some group of patients is always overlooked despite the best of intentions. The problem is made more challenging since it involves both dental insurance coverage for the orthodontic care and medical insurance for the surgical care. Treatment can be covered by one or both, but in some instances will not be covered by either. Unfortunately, the two insurance entities are frequently completely separate and do not coordinate the necessary care approvals.

Collaboration between providers is easier with technology, but the team must guard against the very technology that improves our abilities from separating us. Treatment plans can be done in separate buildings, but then team members risk ‘losing touch’ with one another.

How would you encourage newly qualified doctors to specialise in this field?

This is a small but vital area of learning within both oral and maxillofacial surgery residency and orthodontic residency. The resident and new practitioner who wants to excel in this discipline will need to treat as many cases as possible, learn to coordinate and collaborate with the other discipline, and read the literature from both disciplines. It is a tremendous amount of work but when done, can be one of the most rewarding aspects of clinical practice.

How would you imagine an orthognathic surgery procedure in the next 20 years?
Technology will continue to be a tremendous tool for both disciplines. AI, machine learning, and deep learning will continue to impact the field, but providers must remain grounded in principles while deciding whether specific tools help or hinder our professional growth. At the end of the discussion, it is the provider who wields the tools for the best outcome, not the other way around.

Related posts.

Conley, RS, (2022) Orthognathic surgery past, present, and future. Clinical and Investigative Orthodontics, 81(4), 179–186.

Reyneke, JP, Conley, RS, (2022) Surgical/orthodontic correction of transverse maxillary discrepancies. Oral Maxillofac Surg Clin North Am, 21(1), 53–69.

Conley, RS, Edwards, SP, (2019) Three-dimensional treatment planning for maxillary and mandibular segmental surgery for an adult Class III: Where old meets new. Angle Orthod, 89(1), 138–148.

Conley, RS, Legan, HL, (2006) Correction of severe obstructive sleep apnea with bimaxillary transverse distraction osteogenesis and maxillomandibular advancement. Am J Orthod Dentofacial Orthop, 129(2), 283–292.

Dr R Scott Conley

Dr R Scott Conley is an Associate Professor in the Department of Orthodontics and Oral Facial Genetics at the Indiana University School of Dentistry with nearly twenty five years on the full-time faculty in leading dental and medical schools, with collaborations on adult and paediatric sleep teams and orthognathic surgery teams.

Contact Details




  • American Association of Orthodontists Foundation
  • University of Michigan (M Cubed and Injury Center)
  • American Association of Orthodontist
  • Academy of Academic Leadership


Conley trained under Dr Harry L Legan. He has worked with (and continues to work with) extremely talented and collaborative oral and maxillofacial surgeons at the dental schools and medical centres where he has been employed.

Cite this Article

Conley, R (2023) Orthognathic surgery: Tackling deceptive complexity. Research Features, 148. Available at: 10.26904/RF-148-4834870660

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(CC BY-NC-ND 4.0) This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. Creative Commons License

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