BSSO vs double jaw surgery — how do surgeons decide which one you need?
Orthodontist and surgeon assess bite, skeletal discrepancy, and facial profile together
Cephalometric analysis and 3D imaging used to measure jaw positions and airway
Surgeon decides: BSSO alone, or bimaxillary (double jaw) surgery needed
Patient is fully informed of the plan, the alternatives, and the expected facial changes
Surgery proceeds with the agreed plan — or the plan is formally revised with patient consent
If any of these steps was skipped or rushed — particularly the informed discussion of alternatives — that gap in the planning process may have affected your outcome.
Understanding BSSO and double jaw surgery: what they are and what normally happens
Jaw surgery — technically called orthognathic surgery — corrects the position of the upper jaw, the lower jaw, or both. Surgeons perform it to fix bite problems, breathing difficulties, facial asymmetry, and skeletal discrepancies that braces alone cannot correct.
BSSO stands for bilateral sagittal split osteotomy. During this procedure, a surgeon cuts the lower jaw bone on both sides and repositions it forward, backward, or sideways. Only the lower jaw moves. Recovery takes several weeks, and patients typically spend months in orthodontic treatment before and after surgery.
What double jaw surgery adds
Double jaw surgery — also called bimaxillary osteotomy — moves both the upper jaw (maxilla) and the lower jaw (mandible) in the same operation. The upper jaw procedure is called a Le Fort I osteotomy. Moving both jaws gives the surgeon far more flexibility to achieve a balanced facial profile and a stable bite.
Both procedures are major operations performed under general anaesthetic. Both carry real risks including nerve damage, infection, relapse, and changes to facial appearance. For more general information about jaw surgery, Healthdirect Australia provides a plain-language overview of orthognathic procedures.
Key fact: BSSO moves only the lower jaw. Double jaw surgery moves both jaws simultaneously.
Key fact: The upper jaw procedure in double jaw surgery is called a Le Fort I osteotomy.
Key fact: Moving both jaws gives surgeons more control over the final facial profile and bite stability.
Key fact: In Australia, orthognathic surgery is typically planned jointly by an oral and maxillofacial surgeon and an orthodontist over 12–24 months.
How surgeons decide which procedure to use
The decision between BSSO and double jaw surgery depends on several measurements. Surgeons use cephalometric analysis — a precise measurement of skull and jaw angles from X-rays — to map where each jaw sits relative to the skull base. They also assess the patient’s facial profile, the degree of skeletal discrepancy, and whether the airway would be compromised by moving only one jaw.
A patient with a significant upper jaw problem — such as a retruded maxilla, vertical excess, or asymmetry — will almost always need double jaw surgery. Moving only the lower jaw in those cases produces a poor facial result and an unstable bite. Surgeons also consider sleep apnoea risk, since repositioning the lower jaw alone can sometimes worsen airway obstruction.
When things start to go wrong — warning signs in the planning process
Most problems in jaw surgery trace back to the planning stage, not the operating theatre. A patient who ends up with a poor facial profile, an unstable bite, or an unexpected appearance after BSSO may have been a candidate for double jaw surgery all along.
Warning signs that the surgical plan may not have been right for you:
• Your surgeon never discussed double jaw surgery as an option, even though your upper jaw has a visible problem
• Nobody showed you a predicted facial profile or 3D simulation before surgery
• Your orthodontist and surgeon gave you conflicting information about what the surgery would achieve
• The plan changed close to your surgery date without a full explanation
• After surgery, your bite feels unstable or your face looks significantly different from what you expected
• You were told BSSO would fix your profile, but your upper jaw position was never properly measured
• Your surgeon dismissed your questions about facial appearance as cosmetic concerns
None of these signs automatically means something went wrong. But each one is worth examining carefully, particularly if your outcome does not match what you were told to expect.
A common pattern — where care can break down in jaw surgery planning
Jaw surgery planning failures tend to fall into a small number of recognisable patterns. Understanding these patterns helps you make sense of your own experience.
Underestimating the upper jaw problem. Some surgeons plan BSSO because it is a simpler operation, without fully accounting for the upper jaw’s position. When the upper jaw sits too far back or too high, moving only the lower jaw produces a result that looks unbalanced. The patient ends up with a corrected bite but a facial profile that does not match their expectations — or the surgeon’s pre-operative promises.
Failing to use 3D planning tools. Modern jaw surgery planning uses cone beam CT scans and digital surgical simulation. Surgeons who rely only on 2D X-rays and dental models may miss asymmetries or vertical discrepancies that would have changed the surgical plan. The Australian Commission on Safety and Quality in Health Care sets standards for surgical planning that include appropriate use of imaging technology.
Changing the plan without proper consent. Sometimes a surgeon decides during the operation — or just before it — to proceed with BSSO instead of the planned double jaw surgery, or vice versa. Changing a surgical plan without the patient’s informed agreement beforehand raises serious questions about consent.
Inadequate orthodontic preparation. Double jaw surgery requires different pre-surgical orthodontic preparation than BSSO. A patient whose teeth were prepared for one procedure and then received the other may end up with a bite that does not settle correctly after surgery.
Dismissing profile concerns as cosmetic. Patients who raise concerns about their facial appearance before surgery sometimes hear that the surgery is about function, not looks. But facial profile is a legitimate and measurable surgical outcome in orthognathic surgery — not a cosmetic afterthought. Surgeons who dismiss these concerns may be avoiding a harder conversation about whether the planned procedure is the right one.
Why this matters legally
Every surgeon who treats a patient in Australia owes that patient a duty of care — a legal obligation to provide treatment that meets the standard a competent surgeon in the same field would provide. This duty applies to the planning stage just as much as to the operation itself.
Not every poor outcome from jaw surgery means the surgeon did something wrong. Orthognathic surgery is complex, and some degree of relapse, swelling asymmetry, or bite adjustment is a known risk. A complication that falls within the accepted range of surgical risk is not automatically a failure of care.
But when a surgeon chooses the wrong procedure for a patient’s anatomy — or fails to properly inform a patient about the alternative — the outcome may reflect more than bad luck. For a detailed explanation of how medical negligence law applies to surgical decisions, see Reframe Legal — Medical Negligence.
Post-surgical swelling that takes longer than expected to resolve, or minor bite adjustments needed after BSSO — these are known and accepted surgical risks
A surgeon performing BSSO on a patient whose imaging clearly showed an upper jaw problem requiring double jaw surgery — without discussing the alternative or obtaining informed consent
This is a general educational framework only. Each case is assessed on its individual facts.
When BSSO instead of double jaw surgery may amount to medical negligence
The NSW Civil Liability Act 2002 sets the legal framework for medical negligence claims in this state. Under that Act, a court asks whether a competent surgeon in the same field would have made the same decision — and whether the patient received enough information to make a genuine choice.
Several specific situations may give rise to a legal claim:
If your surgeon performed BSSO when your imaging showed a clear upper jaw problem, and nobody discussed double jaw surgery with you, the planning process may have fallen short of what a competent surgeon would have done.
If your surgeon changed the surgical plan without telling you — for example, deciding during pre-operative preparation to do BSSO instead of the agreed double jaw surgery — that change without your consent may constitute a breach of your right to make an informed decision.
If you asked about double jaw surgery and your surgeon dismissed the question without proper explanation, and your outcome reflects exactly the profile problem you raised, the dismissal of your concern may be relevant to whether you received adequate information.
If revision surgery became necessary because BSSO produced an unstable bite or a facial result that double jaw surgery would have avoided, the cost and harm of that revision may be recoverable.
When harm becomes long-term or permanent
For most patients, the consequences of the wrong jaw surgery procedure extend well beyond the initial recovery period.
Physical consequences
A patient who needed double jaw surgery but received only BSSO may develop bite instability over time. The teeth do not meet correctly, and the jaw muscles work harder to compensate. Temporomandibular joint (TMJ) problems — pain, clicking, and restricted jaw movement — can develop months or years after surgery. Some patients require revision surgery, which carries its own risks and a longer recovery.
Nerve damage is a known risk of BSSO. Permanent numbness or altered sensation in the lower lip and chin affects a small but real percentage of patients. When the wrong procedure was chosen, the patient carries this risk without having received the benefit the surgery was supposed to deliver.
Psychological and financial consequences
Jaw surgery is a significant undertaking. Patients spend years in orthodontic preparation, take weeks off work, and often make the decision partly because of how they expect to look and function afterwards. When the result does not match what they were told to expect — particularly when the facial profile looks worse or unchanged — the psychological impact can be severe.
Anxiety, depression, and body image distress are documented consequences of poor orthognathic outcomes. Financial harm compounds this: revision surgery in Australia can cost $20,000 to $50,000 or more, and many patients also lose income during extended recovery periods.
Unexpected facial appearance after surgery
Bite that does not feel stable
Prolonged swelling or asymmetry
Need for additional orthodontic treatment
TMJ pain and dysfunction developing over months or years
Permanent nerve numbness in lip or chin
Revision surgery required
Psychological distress and body image impact
What compensation can cover in jaw surgery cases
In NSW, compensation for a successful medical negligence claim can cover several categories of loss. These include pain and suffering, lost income during recovery and revision surgery, the cost of revision surgery itself, ongoing treatment costs, and the cost of care provided by family members.
| Level of harm | Typical compensation range |
|---|---|
| Moderate injury | $50,000–$150,000 |
| Serious injury | $150,000–$500,000 |
| Severe / life-changing injury | $500,000+ |
Each case is assessed on its own facts. These figures are general ranges only. In jaw surgery cases, the need for revision surgery and the cost of that procedure often forms a significant part of the claim.
Time limits apply in NSW. Generally, a person has three years from the date they knew — or ought reasonably to have known — that they suffered harm as a result of a care failure. For surgical planning decisions, that date is not always obvious, and getting early legal advice about time limits is important.
Bringing it together — do the pieces fit?
If you are reading this because something about your jaw surgery outcome does not feel right, the following questions may help you think clearly about what happened.
Connecting the dots between a surgical planning decision and a poor outcome takes careful analysis of your records, your imaging, and the clinical notes. For a plain-language explanation of how that process works, see Reframe Legal — How Medical Negligence Claims Work in NSW.
You don’t need certainty to understand your position
Many people who had a difficult jaw surgery experience spend years wondering whether what happened to them was normal. Surgeons sometimes tell patients that their result is within the expected range. That may be true. But it may also be a way of closing down a conversation that deserves to stay open.
You do not need to be certain that something went wrong before you seek information. Legal clarity comes from examining the facts — your records, your imaging, your consent documents, and what a competent surgeon in the same situation would have done. That examination is what a specialist lawyer does.
Consent is a particularly important issue in jaw surgery. A patient who was never told that double jaw surgery was an option — or who was told BSSO would achieve a result it could not achieve — may not have given truly informed consent. For more on how consent failures work in a legal context, see Reframe Legal — Informed Consent and Medical Negligence.
If you want to understand whether your surgeon’s conduct meets the standard expected in Australia, AHPRA — Australian Health Practitioner Regulation Agency regulates oral and maxillofacial surgeons and accepts complaints about registered practitioners.
About the lawyer behind this article
Dr Rosemary Listing is a NSW lawyer with a PhD in medical negligence. Her academic and clinical background gives her an unusually detailed understanding of how surgical planning decisions get made — and where they go wrong.
Rosemary has worked on cases involving orthognathic surgery, including situations where patients received BSSO when their anatomy indicated a need for double jaw surgery. She understands the technical language of cephalometric analysis, surgical simulation, and consent documentation — and she knows how to read those records in a legal context.
In her experience, harm in jaw surgery cases rarely comes from a single dramatic error. More often, it accumulates across a planning process where the right questions were never asked, the right imaging was never reviewed, or the patient was never given a genuine choice between procedures.
Her clients come to her wanting to understand what happened — not to blame anyone, but to make sense of an experience that left them worse off than they expected. Rosemary’s role is to assess whether the care they received met the standard a competent surgeon would have provided.
Rosemary practises in NSW and accepts enquiries from people across Australia whose surgery was performed in this state.
This article is general legal information only. It does not constitute legal advice. Each person’s circumstances are different. The law discussed applies to New South Wales, Australia. Time limits apply to legal claims.