In short. The incision sits behind the last molar, so no scar crosses the face or the neck. What that buys, and what access through the mouth costs in view and healing.
Key points
- Because there is no scar on the face to watch, the thing that occupies the first months is swelling instead.
- The face reads wider than expected at two weeks, unevenly at two months, and close to its final width only much later.
- That is the price of this approach rather than a sign that anything has gone wrong.
An angle reduction is reached through an incision inside the mouth, made in the lining behind the last molar. Nothing is cut through the skin of the face or the neck, which is why the operation leaves no visible scar. That is a real advantage and it is not the whole story, because the approach also determines what the surgeon can see, what the mouth has to tolerate afterwards, and how the first two weeks feel.
What the hidden incision buys
A scar on the face is permanent and its maturation is unpredictable, which is why an operation on the jaw that can avoid one does. Placing the incision inside the mouth also keeps the scar where it is not exposed to sunlight and where the lining heals quickly. Patients sometimes describe this as scarless surgery. It is not: a cut was made, it heals with a scar, and the scar is inside the mouth where it cannot be seen.
What the swelling hides is the result, not a scar
Because there is no scar on the face to watch, the thing that occupies the first months is swelling instead. The face reads wider than expected at two weeks, unevenly at two months, and close to its final width only much later. That is the price of this approach rather than a sign that anything has gone wrong.
What access through the mouth costs
The view of the bone is narrower than it would be through an incision on the outside, and the light has to reach around the corner of the mouth. The field is shared with the bacteria that live in the mouth, so the plan includes attention to dental and gum health before the operation and to mouth hygiene afterwards. Sutures inside the mouth dissolve on their own, which means less to remove and also a period in which the lining is tender.
The first weeks from the inside
Eating is awkward because the lining is swollen and the muscles of chewing are bruised. Speaking is effortful at first. Mouth opening is limited, brushing has to be done carefully around the incision, and the taste of blood is common in the first days. The swelling inside the mouth settles faster than the swelling in the face, so eating becomes easier before the width can be read. None of this is visible to anyone else, which is exactly why patients are surprised by it.
Reasons the mouth is assessed first
- Active decay, an infected tooth or untreated gum disease, all of which sit in the operative field.
- A tooth close to the line of the incision, which is identified before the operation rather than after it.
- Smoking, which impairs healing in the lining of the mouth as well as in bone.
The approach is the reason this operation leaves no mark on the face, and it is also the reason preparation includes a dental examination and aftercare includes the mouth. Understanding both halves of that is what makes the first fortnight manageable.
Frequently asked questions
Where exactly is the incision, and can I see it myself?
It is made in the lining of the mouth behind the last lower molar on each side, running backwards along the inside of the jaw. Most patients can see it with a torch and a mirror, though the back of the mouth is awkward to inspect. The sutures dissolve on their own, and the scar they leave is inside the mouth rather than on the skin.
Can the incision inside the mouth become infected?
It can, which is why the mouth is assessed and treated before the operation rather than after it. Decay, an infected tooth and untreated gum disease all put bacteria in the operative field, and an infection reaching the bone is a serious problem to treat. After surgery, increasing pain or swelling after the first week, discharge or a bad taste are signs that need the team rather than patience.
Does an operation through the mouth affect how I speak afterwards?
For a while, yes. The lining is swollen and the muscles of chewing are bruised, so speech is effortful and some sounds are awkward in the first days. It usually improves as the swelling settles, well before the shape is judged. Speech that is unchanged at several weeks, or that is getting worse, is worth raising with the team rather than waiting out.
Risks & Limitations
- The change is permanent and the amount removed is treated as fixed. Bone that has been taken away cannot be put back, and material added later does not behave like the mandible it replaces.
- The canal carrying the nerve to the chin runs inside the bone being cut. Numbness of the chin and lower lip is expected rather than rare, usually improves over months, and may not return fully.
- The nerve that moves the lower lip runs near the outer surface of the bone. Weakness after surgery is usually temporary and usually resolves; a lasting weakness is uncommon but possible.
- The vessels supplying the face run close to the surface of the angle. Bleeding afterwards is the complication this operation most wants to avoid, because a collection of blood in the floor of the mouth can compromise the airway.
- The masseter is detached from the bone it was attached to and reattaches. Width can partly return if the muscle thickens again, which is not the bone growing back.
- Swelling hides the result for months. The face reads wider than expected at two weeks, unevenly at three months, and the result is judged honestly at around a year.
When to Seek Care
- Difficulty breathing, a feeling of pressure or swelling in the floor of the mouth, or difficulty swallowing. Seek emergency care at once.
- Swelling that is increasing rather than settling after the first week, or that is much greater on one side. Contact the team.
- Weakness of the lower lip that appears after the first week, or that is worsening rather than improving.
- Numbness that is spreading rather than staying stable, or a wound in the mouth that is opening or discharging.
- Fever, or feeling generally unwell with a swollen and tender jaw. Calf pain or swelling in one leg, or chest pain and shortness of breath, need emergency care at once.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
- National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
- Cochrane Library — systematic reviews
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.