BSSO, described by H. Obwegeser, is a well known surgical procedure which is used worldwide from more than 50 years.

That surgical technique is often responsible of some damage: mental nerve disturbances, pseudarthrosis, condylar resorption.

We observed 10 years ago, when we used transmandibular symphyseal distraction, not only correction of crowding but also mandibular lengthening.

6 years ago, in some clinical cases of class II malocclusion with maxillo mandibular crowding we began to use an original approach in 2 steps:

• 1st step: mandibular symphyseal distraction

• 2nd step (3 or 4 weeks later): removal of symphyseal distractor and osteosynthesis with plate and screws maxillar distraction with repositioning.

• After the 1st step, we observe that class II become class III and we prepare the second surgical step to obtain class I occlusion (presentation of the steps of preparation).

• In a lot of cases, that 2 steps procedure remains the only heavy maxillo mandibular procedure.

• After orthodontic treatment, chin and nose surgery are performed if necessary to achieve facial harmonization.

• About 80 patients were treated by this procedure.

• Presentation of cases.

Conflict of interest: None declared.