Mandibular osteotomy
The bilateral sagittal split osteotomy of the mandible (Epker/Dal Pont technique) gently mobilises the part of the lower jaw that carries the dental arch and the chin, to correct its position. It is the reference procedure for a receding (class II) or asymmetrical lower jaw. It is frequently combined with a Le Fort I maxillary osteotomy; this is then called a bimaxillary osteotomy.
Indications
Receding mandible (retrognathia): receding chin, upper teeth far forward, lips that do not close at rest.
Mandibular asymmetry, deviated chin.
Obstructive sleep apnoea: mandibular advancement, often combined with maxillary advancement, widens the airway.
Expected benefits
They are functional, with an aesthetic impact:
a normal relationship between the teeth and normal chewing, which in the long term prevents tooth wear, loosening of the teeth and jaw joint disorders;
a lower risk of sleep apnoea syndrome;
a normal relationship between the jaws when the discrepancy makes prosthetic rehabilitation impossible;
a harmonious face, from the front and in profile.
Principle
The incision is inside the mouth, on the gum beyond the lower molars, on each side: it is invisible, there is no skin incision. The two osteotomies (one per side) separate the lower dental arch from the rest of the jaw along an oblique line; the segment is moved to the planned position, guided by the 3D-printed surgical splint, then fixed with titanium mini-plates and screws. The osteotomies are performed with a piezotome (ultrasound), which cuts the bone without injuring the soft tissues or the nerve.
Specific points
Duration: about 2 hours when not combined with a maxillary osteotomy.
Hospital stay: 1 night.
The lower wisdom teeth are removed at least 6 months beforehand.
Swelling mainly in the lower third of the face and the lower lip.
Numbness of the lower lip, chin and lower incisors: expected, recovers over weeks to months; persistent in fewer than 10% of cases.
Painful limitation of mouth opening during the first weeks, which fades with vertical mobilisation exercises of the mandible and lip contraction exercises; maxillofacial physiotherapy is often prescribed from week 3.
Recovery
Guide to the first 6 weeks on the orthognathic surgery page: liquid diet for the first week, then blended or minced food for 5 to 6 weeks, careful brushing despite the elastics, no smoking, ice during the first few days. Orthodontics resumes about 6 weeks after the operation.
FAQ
Is the jaw weaker afterwards?
No: at 6 weeks the bone has healed and the plates no longer bear any load. Contact sports from 3 months.
Do the plates stay for life?
Generally yes. If they become bothersome, they are removed during a short procedure, possible from 6 months.
Can a mandibular osteotomy be done on its own?
Yes, when only the mandible is involved. For large discrepancies or asymmetries, a bimaxillary osteotomy gives a more stable result.
What is the limit of advancement?
Beyond 8 to 10 mm, a bimaxillary osteotomy is preferred for stability and for the aesthetics of the profile.