Mandibular plane: the line of the base of the jaw

The mandibular plane is a reference line that follows the base of the mandible. In cephalometry, it is drawn from the lowest, most posterior point of the angle of the mandible, the gonion, to the lowest point of the chin, the menton. In clinical assessment, the same idea works as the imaginary line a person sees when looking at the face from the side.

How is it measured and interpreted?

The most common measurement is the angle between the mandibular plane and a horizontal reference plane, such as the Frankfurt plane. Values vary between authors and populations, and the interpretation belongs to the professional taking the measurement.

This description is general. It is not a rule for a specific patient, and orthodontic or surgical diagnosis belongs to those who treat malocclusions and dentofacial deformities.

Why does it matter in HOF?

The harmonization professional does not alter the bone, but works on top of it. The mandibular plane helps in understanding what filler can and cannot do.

• Contour definition: in patients with a steeper plane, the jawline tends to look less crisp. Jawline filler acts on soft tissue, and the result depends on the bony base.
• Relationship with the chin: in someone with retrogenia, the plane and the position of the chin influence the profile. The chin is often part of the conversation.
• Mandibular angle: the opening of the mandibular angle is part of the perception of square or rounded.
• Expectation: a patient who wants a "sculpted" jawline may have a base that limits the effect. It is better to agree on this at the consultation.

What does the mandibular plane not do?

It does not, on its own, decide volumes or injection points. Nor does it replace orthodontic assessment or orthognathic surgery when there is a significant skeletal discrepancy. When the patient has a marked bony disproportion, referral is part of the care.

Also known as: plane of the base of the mandible, gonion-menton plane.