Challenges and opportunities facing contemporary orthognathic surgery

Psychosocial evaluation

One of the major challenges facing orthognathic surgery is the patient with underlying psychological and/or psychiatric problems, particularly when such issues remain undiagnosed until the postoperative period. Body image dissatisfaction may have a multifactorial aetiology, but the increasing prevalence over the last few decades is likely partly a result of substantial sociocultural contributions (Phillips et al., 2012). The pervasive influence of predominantly vacuous celebrities on empty reality television programmes, commonly on mainstream media, aimed particularly at the impressionable young, has infiltrated modern society through an irresponsible media. Together with the massive increase in use of social media in an image-conscious era of selfies and increased preoccupation with facial appearance, such influences exploit the unwary, but the media bears none of the responsibility for foisting this empty nonsense onto a gullible public. Therefore, it is imperative that clinicians become familiar with red flag signs exhibited in the patient history and interview, in order to rule out mental health issues, particularly the often-severe body image disorder known as body dysmorphic disorder (BDD). The prevalence of BDD is thought to be approximately 2% in the general population, but may be as high as 50% in cosmetic surgery patients (Phillips et al., 2012). The orthognathic patient is likely to be somewhere between the two, with one study finding approximately 10% of orthognathic patients demonstrating BDD symptoms (Vulink et al., 2008). Patients with BDD have a distorted view of their appearance, hence the term ‘imagined ugliness’. Orthognathic treatment on a patient with underlying body image disorders usually will not improve the psychological symptoms, and may even worsen them, leaving the clinical team with a dissatisfied patient, albeit with an objectively good outcome. Two recent book chapters specifically focus on BDD and the orthognathic patient, discussing the importance of preoperatively diagnosing BDD, how to inform patients of the need for mental health evaluation, and how to handle a patient when the BDD diagnosis becomes evident only after surgery, and recommendations for mental health clinicians from a surgeon’s perspective (Naini, 2017; Phillips and Crerand, 2017).

Ideally, every orthognathic team should include a clinical psychologist or liaison psychiatrist with expertise in the field to assess patients prior to treatment and during treatment as required. The use of pre-treatment BDD screening questionnaires, such as the BDDQ, should be standard practice (further information is available at www.KatharinePhillipsMD.com).

Soft tissue paradigm?

Treatment planning in orthognathic surgery (and orthodontics) may be ‘occlusion-centred’ or ‘aesthetic-centred’. In the former, facial soft tissue aesthetics are permitted to alter, perhaps detrimentally, at the expense of achieving a Class I incisor relationship and well-interdigitated buccal segment relationships. In the latter or aesthetic-centred approach, the patient’s soft tissue profile and upper lip to maxillary incisor relationship is considered paramount. Therefore, dentoskeletal changes, including the degree of decompensation, should be planned to achieve the desired soft tissue outcomes; for example, at times, an increased incisor overjet and Class II occlusion may be accepted or only partially corrected, rather than attempting to achieve a Class I incisor relationship through retroclination/retraction of the maxillary incisors, thereby avoiding potentially detrimental changes to the facial profile. In short, the teeth are made to fit the face, and not the other way around.

Describing the move from ‘treating to cephalometric norms’ or to obtain an ‘ideal’ dental occlusion at all costs being superseded by planning to obtain ideal facial soft tissue aesthetics as a modern paradigm shift is rather misleading, as there is in fact nothing new in planning orthognathic surgery based on the ultimate aesthetics of the facial soft tissue outcome. As far back as 1908, the eminent orthodontist Rodrigues Ottolengui argued for this approach (Ballin, 1908), and pioneering surgeons such as Hugo Obwegeser sometimes worked with artists and based dentoskeletal repositioning for orthognathic patients on proposed ideal soft tissue profile aesthetics. It is true that the inexperienced orthodontist will often place undue reliance on ‘treating to cephalometric norms’, but this should now be the exception rather than the rule. In addition, as our understanding of the soft tissue responses that occur with skeletal repositioning improves, the accuracy of soft tissue predictability should also improve (Gill et al., 2017), although the problem of individual variability with the alteration of soft tissue changes in relation to hard tissue movements will be difficult to overcome. The aesthetic predictability of skeletal expansion versus contraction in treatment planning, for example the degree of maxillary advancement versus mandibular set-back in a Class III patient, is an area that requires further exploration.

Technological innovations

One of the major innovations in modern orthognathic surgery is the development of virtual 3D surgical planning, a move that has been inevitable considering the use of 2D planning software for a number of decades. Advances in 3D imaging with high resolution and lower radiation cone beam computed tomography permit computer-aided design/computer-aided modelling (CAD-CAM) systems to aid orthognathic surgical planning. The level and inclination of osteotomies may be more accurately planned preoperatively, and for highly complex osteotomies customised cutting guides or stents may be prefabricated in an attempt to improve accuracy (Mazzoni et al., 2015; Zhang et al., 2016). Different manufacturers and their respective systems allow either dental impressions to be digitised, or better still, for intraoral scans of the dentition to be taken and overlaid onto the preplanning CT scan, permitting dentoskeletal movements to be evaluated on the computer monitor. Subsequently intermediate and final surgical wafer splints may be fabricated by 3D printing. Very accurate customised implants/onplants may also be prefabricated (Suojanen et al., 2016), which is particularly useful for complex asymmetry patients. Cranio-dentoskeletal stereolithographic models also allow pre-bending of fixation plates (Brunso et al., 2016), which may be an intraoperative time-saving measure.

It is worthwhile to stress that such technological advances, despite their possible advantages, do not replace trained clinical judgement. Computers can help a great deal but cannot plan for you. Therefore, excessive reliance on computers combined with a lack of focus on diagnosis and planning on the patient at the chair side, particularly during training, should be avoided.

Patient age in relation to surgical timing

The skeletal repositioning part of orthognathic care is generally carried out after the majority of facial growth has occurred. Experienced teams often begin orthodontic preparatory treatment at such an age that when the patient is ready for surgery they are also unlikely to have any further significant growth potential. However, occasionally earlier surgical intervention may be required for specific psychosocial, aesthetic or functional reasons, particularly during adolescence. Data on appropriate timing of surgery in growing patients is sparse, and the adverse effects of such surgery on subsequent growth are not fully understood. Mehra and Wolford (2017) have discussed the available evidence, including treatment options, the effects of surgery on postoperative growth patterns, potential complications, and the importance of informed consent in such patients.

‘Surgery First’ versus conventional surgery

Conventional orthognathic surgery often involves a few years of orthodontic treatment with the actual skeletal repositioning surgery undertaken at some point during the orthodontic treatment, usually about half or three-quarters of the way through the process. The principal downsides to this approach are the overall length of treatment, and the worsening effect of preoperative incisor decompensation on facial aesthetics, particularly in Class III patients. An alternative method, first described by Behrman and Behrman (1988), but predominantly promoted in East Asia, is referred to as ‘Surgery First’, and involves a reversal of the traditional pathway, with skeletal repositioning preceding orthodontic treatment. The potential advantages cited are reduced treatment time, possibly partly due to faster postoperative tooth movement (regional acceleratory phenomenon) (Liou et al., 2011), and improved facial aesthetics early in treatment.

The problem appears to be one of designated nomenclature. Common sense would suggest that surgery should be undertaken at the appropriate time for each patient (Hernández-Alfaro and Guijarro-Martinez, 2017). Some patients may not require orthodontics at all, for example, bimaxillary advancement for sleep apnoea. Some patients may benefit from surgery early in orthodontic treatment (Naini and Witherow, 2016), and others will inevitably require a prolonged period of orthodontic preparation, for example in severe Class II division 2, deep overbite malocclusions. It is incumbent on orthodontists not to waste time during orthodontic preparation, but it is also irresponsible to pretend that a ‘Surgery First’ approach is a panacea or transformative quantum leap in orthognathic surgery.

Computer-aided navigation

The development of CAD-CAM technology and virtual surgical planning has been discussed above. Another area of development is intraoperative computer-aided surgical navigation. Surgical navigation is comparable to a global positioning system commonly used in cars. The three main component parts include a localiser (analogous to the satellite), the surgical probe or instrument and a CT scan data set (analogous to the road map) (Mazzoni et al., 2010). Surgical navigation systems were initially developed for neurosurgery, but their use in maxillofacial surgery is increasing, and there may be potential benefits in orthognathic surgery, particularly in relation to the avoidance of critical structures and thereby improved safety (Zinser et al., 2013). For example, the exact position of the tip of any surgical instrument can be assessed intraoperatively as the instrument is being used, improving safety in relation to the mandibular nerve, lingual nerve and pterygomaxillary fissure during pterygoid disjunction (Mazzoni et al., 2010).

Endoscopic approaches and minimally invasive surgery

Minimally invasive surgery has produced significant advances in many parts of surgery, as reduced soft tissue trauma often results in reduced postoperative discomfort and morbidity, and potentially faster patient recovery. Reduced soft tissue manipulation may decrease the risk of bleeding and oedema. The use of endoscope-assisted orthognathic surgery may increase in the future, and may be beneficial in selected cases, though a steep learning curve and further development of techniques are still required (Klein et al., 2017).

Bioresorbable plates

In orthognathic surgery, bioresorbable plates offer a potential clinical advantage over standard titanium plates by eliminating the possible need for a second operation for their removal, eliminating the albeit small amount of interference with postoperative CT scans, and any potential leakage from the titanium into soft tissues over the long term. A meta-analysis comparing the complications of bioresorbable and conventional titanium fixation in two trials found no significant difference between the two groups in terms of complication rates (Yang et al., 2013). Nevertheless, this is an area requiring continued development.

Neurosurgery drills and piezo-surgical saws

Neurosurgery drills, which stop automatically in contact with soft tissue, are now used regularly by maxillofacial surgeons. Neurosurgeons become so skilled that they can eventually decorticate a raw egg, leaving the membrane intact. Maxillofacial surgeons train by drilling holes through cadaveric bone and freeing rubber bands fed through the bone, simulating nerves such as the mandibular nerve, without lacerating the band. The potential benefits of both neurosurgery drills and piezosurgery are reduced nerve injury, reduced blood loss and reduced likelihood of tooth damage, though there may be an increased surgical duration due to a reduction in speed.

Day case or ambulatory surgery

There is a distinction between day case orthognathic surgery, where a patient is operated on in the same hospital setting as a routine orthognathic patient, but discharged on the same day, and the term ‘ambulatory’ surgery, which generally means that the patient receives the treatment in an ‘office’, that is, practice setting. The latter case of ambulatory surgery, sometimes undertaken with heavy intravenous sedation rather than general anaesthesia, is predominantly a financially driven issue that affects healthcare in some countries, but should be kept out of the patient health-driven British NHS. It will not be discussed further here. However, the concept of undertaking orthognathic surgery as a day surgery procedure is sometimes discussed, though rarely carried out in the UK. In a young, fit and healthy patient, requiring a relatively smaller procedure, for example sagittal split osteotomy only, there is a possibility that they may be able to be discharged earlier. However, most surgeons consider the potential complications, though uncommon, to be an adequate reason to keep the patient under observation overnight in a hospital setting with adequately trained staff at hand. It may be worth remembering the age-old maxim, to do for your patient what you would do for a member of your immediate family.

Distraction osteogenesis

In the 1990s distraction osteogenesis began to be promoted as an alternative to standard orthognathic surgical procedures. Over time the techniques have evolved, particularly in that bulky external devices have become miniaturised and intraoral as almost standard, having been developed by Guerrero in particular (Guerrero, 2017; Guerrero et al., 2017). The technique also appears to have found its niche, usually in severe craniofacial syndromic patients requiring extensive moves beyond the realms of standard orthognathic surgery.

Mandible-only surgery for anterior open bite correction

Orthognathic surgery initially began with the development of mandibular surgical procedures, and early pioneering surgeons, such as von Eiselsberg, Babcock, Limberg, Kostečka and Kazanjian demonstrated the correction of significant anterior open bites with a variety of mandible-only osteotomies. However, with the development of maxillary osteotomies, where the aetiology of the open bite is predominantly posterior vertical maxillary excess, some form of superior repositioning of the posterior maxilla is required. Nevertheless, in appropriately selected cases, anticlockwise rotation of the distal (tooth-bearing) segment of a sagittal split osteotomised mandible may be used to close an anterior open bite. This approach has been pioneered by the American maxillofacial surgeon Dale Bloomquist (Bloomquist and Joondeph, 2017).

Sleep apnoea

Obstructive sleep apnoea (OSA) is a debilitating medical condition. In appropriate patients having undergone mandatory multidisciplinary assessment in a sleep clinic, orthognathic surgery may be the most effective intervention (Messiha et al., 2017). The type of surgery required depends on the level of the airway obstruction. Mandibular advancement pulls forward the base of the tongue, improving the patency of the oropharyngeal airway, and maxillary advancement pulls forward the soft palate, opening the velopharyngeal airway. Bimaxillary advancement results in enlargement of the retropalatal and retrolingual airway (Camacho et al., 2015), resulting in a consistent and significant reduction in the apnoea–hypopnea index (Caples et al., 2010). Although relapse following bimaxillary advancement surgery may range from 10 to 20%, the improvement in the apnoea–hypopnea index appears to remain stable (Camacho et al., 2015). In some patients a trade-off may be required between improved quality of life due to reduction of OSA symptoms, and possible detrimental aesthetic effects of significant bimaxillary advancement (Messiha, et al., 2017).

Facial feminisation surgery

Orthognathic surgery is part of the set of procedures which aim to feminise the face. Such surgery is usually undertaken in transsexual patients transitioning from male to female, but may also involve female patients desiring to feminise certain aspects of their face. Even if not directly involved in such treatment, it is imperative for orthodontists and surgeons to be aware of the procedures involved in order to be able to provide sound advice to patients (Altman, 2017).

Concomitant temporomandibular joint surgery with orthognathic surgery

Temporomandibular joint (TMJ) pathology (e.g. rheumatoid arthritis) may prevent satisfactory mandibular function and stability. In severe cases, the joints may be ankylosed or otherwise unsalvageable, and the patient may require TMJ replacement surgery (Wolford et al., 2002). Patients with severe malocclusion and irreparable TMJ pathology may benefit from combined joint replacement with simultaneous orthognathic surgery. Surgical planning must be extremely accurate for such patients, and virtual surgical planning as described previously may be beneficial (Matthews et al., 2017). The orthodontist involved in such cases must be aware of the nuances involved, including the difficulties in placing brackets due to reduced access on the ankylosed TMJ side of the dentition.

Virtual surgery simulation for training

A surgery simulator is computer technology designed to simulate surgical procedures for training, obviating the need for practising on patients, cadavers, and perhaps equally importantly on animals, as animals surely have historically suffered enough at the hands of humans. The concept is based on video gaming technology, and with the development of 3D graphics and the use of motion sensors allowing realistic movement and control, such technology is likely to be the future of surgical training. A virtual surgery model has been developed by Pravin Patel, Professor of Plastic, Reconstructive and Craniofacial Surgery in Chicago, specifically for training in orthognathic surgery (Patel, 2018, personal communication).

Hilotherapy

Hilotherapy is the application of cold compression at a regulated temperature through a face mask. Its efficacy is based on reducing postoperative oedema and pain, and improving patient comfort. Though more commonly used by orthognathic surgeons, there is still no clear consensus regarding its use in orthognathic surgery. A meta-analysis demonstrated that hilotherapy was associated with significant reductions in facial pain and oedema in the early postoperative period, and patients reported more comfort and satisfaction with hilotherapy than with cold compression (Glass et al., 2016). The effect on ecchymosis and haematoma formation remains uncertain.

Botulinum neurotoxin

Botulinum toxin type-A injection into the masticatory muscles induces reversible partial paralysis and weakness of the muscles. Seok and Kim (2018) have suggested that injection of botulinum toxin type-A into the masticatory muscles following orthognathic surgery improves stability and reduced trismus, though these assertions appear to be based on their treated cases rather than clinical trials. In addition, it has been suggested that similar injections into the anterior belly of the digastric muscles reduces the mandibular rotation leading to postoperative anterior open bite recurrence (Seok and Kim, 2018; Zdilla, 2015).

Ethical implications

The principal ethical issue facing orthognathic surgery in the UK is related to the level of training required to carry out such procedures, both for surgeons and orthodontists. By definition, a general surgeon could undertake orthognathic surgery, though it would be ill-considered and presumably impossible to defend in a court of law. Nevertheless, there is nothing to stop a subspecialised head and neck cancer surgeon undertaking orthognathic procedures in private practice. The argument to support this is that specialty registrar training in maxillofacial surgery covers orthognathic surgery. The argument against this is that a patient is likely to be better off under the care of a surgeon undertaking orthognathic surgery a few times per week, rather than a few times per year. The improvements in cleft care in the UK resulting from centralisation, combined with high-volume, audited care speak for themselves. This is a difficult area, and learned societies representing surgeons often leave such issues to the common sense and level-headedness of the individual surgeons. The same problem exists for orthodontists. Lack of experience makes many things appear easier than they are, and any orthodontist who thinks orthognathic surgery is easy lacks experience by definition, though it is easy to do badly. It may be that the British Orthodontic Society (BOS) and the British Association of Oral and Maxillofacial Surgeons may consider providing guidelines as to who should undertake orthognathic treatment, and the level of training and experience required.

Political implications

Reluctance to increase funding for the NHS usually results in non-emergency and non-life-threatening procedures facing dilution of funding. Clinicians involved in orthognathic care are very aware of the hugely positive impact that such treatment has on the quality of life of patients, both in the short term and long term; for example improvement in self-esteem, and functional improvements, such as incising food, mastication, eating in public without fear or embarrassment, improved swallowing due to achievement of a lip seal, reduced potential for trauma, both to prominent incisor teeth and in terms of biting the tongue when the maxilla is transversely restricted, or biting the cheeks, and improvements in respiration and symptoms of sleep apnoea, TMJ dysfunction, speech and drooling. The most common pronouncement from patients following orthognathic treatment is that it has changed their lives.

The development of the Index of Orthognathic Functional Treatment Need (IOFTN) in the UK by the University of Bristol, Eastman Dental Hospital, and Consultant Orthodontic Group of the BOS is laudable (Ireland et al., 2014). Nevertheless, due to the inevitable difficulties with NHS commissioning it is vital for the profession to demonstrate further the importance of orthognathic surgery on quality of life with patient-reported outcomes measures (Mazzaferro et al., 2017; Schwitzer et al., 2015).