Lower Face

The lower face is the bottom third of the lateral profile, spanning from the base of the nose down through the lips, chin, and into the throat. It is the region most obviously shaped by the jaws and teeth, which makes it the part of the profile that orthodontic treatment influences most directly and most visibly.

Within the lower face, the chin's projection, the fold between the lower lip and chin (the mentolabial sulcus), and the general contour of the jawline are the key features assessed. Because these structures sit right below the dental arches, changes in tooth position, jaw growth, or mandibular advancement all show up here first.

What It Evaluates

The clinician looks at how far forward the chin sits relative to the rest of the face (chin projection), the depth and angle of the groove between the lower lip and the chin (mentolabial sulcus), the smoothness of the jawline contour, and, more generally, the length and cleanliness of the area under the chin (submental region), which contributes to how "defined" the lower face and neck appear in profile.

Learn more: Chin Projection: How It's Measured & Why It Sets Profile Balance — Qoves Studio

Key References / Landmarks

  • Pogonion, soft tissue (Pog') — the most forward-projecting midline point of the chin pad; the primary reference for chin projection.
  • Labrale inferius (Li) — the mucocutaneous border (vermillion edge) of the lower lip; forms one arm of the mentolabial angle.
  • Sublabiale (Sbl) — the deepest point of the mentolabial fold, also called the soft-tissue B point; sits between the lower lip and the chin pad.
  • Mentolabial angle — the angle formed at sublabiale between the lower lip and the chin pad; an ideal/most-attractive range is often cited around 107°–118°, with a commonly referenced target near 130° and typical population ranges of roughly 115°–145° in men and 120°–130° in women (values vary by ethnicity).
  • Mentolabial sulcus (labiomental fold) — the visible groove itself; a shallow sulcus is often seen with bimaxillary protrusion, while a deep sulcus is common in Class II division 1 malocclusion with a retrusive lower lip and prominent chin pad.

Learn more: Mentolabial Depth: How It's Measured & Why It Defines Chin Strength — Qoves Studio

Clinical Interpretation

Chin projection and the mentolabial fold are strongly influenced by the sagittal position of the mandible, the inclination of the lower incisors, and lower lip posture — all factors an orthodontist can affect through tooth movement, growth guidance, or by coordinating with orthognathic/genioplasty planning in more severe cases. A retrusive pogonion with a deep mentolabial sulcus often accompanies a Class II skeletal pattern, while a shallow or absent sulcus with a very prominent chin can be a sign of bimaxillary protrusion or a Class III tendency. Because the lower face is where the effects of treatment are most visible, clinicians use these landmarks both to diagnose the underlying skeletal relationship and to predict how proposed tooth movements (for example, retracting or advancing the lower incisors) will change the soft-tissue chin and lip contour once treatment is complete.

Learn more: Facial Convexity & Landmarks in Orthodontic Diagnosis: Mentolabial Angle by Dr Mike Mew — YouTube

References