Sushner line: lips and profile

The Sushner line, also called the S2 line, was described by Sushner in 1977, in the American Journal of Orthodontics, from a photographic study of the profile of Black adults. It is drawn from the soft tissue nasion to the soft tissue pogonion, and lip position is read by the distance of each lip from this line. In the original sample, the lips sat in front of it, and the author argued that lines designed for European profiles (such as those of Ricketts, Steiner, and Holdaway) did not describe naturally more protrusive profiles well. Reference values depend on the population and sex; for this reason, it is worth citing the source when using them.

Why are there so many profile lines?

The soft tissue profile has been analyzed for decades by orthodontists and surgeons, and each school proposed its own line. They all answer the same question: are the upper lip, the lower lip, and the chin in a balanced relationship? The Burstone line, the Ricketts line, the Steiner S line, and the Holdaway H line are the best known. The starting points change (subnasale, tip of the nose, base of the nose), as does the end point (soft tissue pogonion or a nearby point).

Because each line has its own reference values, mixing measurements from different lines leads to wrong conclusions. The practical rule is simple: choose one, record which, and keep the same criterion in follow-up photos.

How to use it in facial planning

The value of the line is not in the number but in the question it provokes. If the lips look too projected, the chin may be recessed (see retrogenia). If the lips look retracted, the problem may lie in the base of the nose or in the dentition. In every case, the facial profile should be read as a whole.

What to avoid

• Treating the reference value as a target volume for the lip.
• Applying references from one population to patients with a different morphology, without adjusting the criterion.
• Planning from the profile alone, forgetting the frontal view and smile dynamics.
• Promising the patient a specific profile.

How to explain it to the patient

Simple language works better than technical terms. Example: "Looking from the side, I can see how the lip and chin sit relative to each other. That helps me decide where it makes sense to work and where it does not."

In Harmy

The app works with a frontal photo and does not analyze the profile. The Lips and Chin points simulate, from the front, the marked area with the volume in ml entered, as an illustrative simulation. Profile reading and the choice of reference line are left to the professional.

Also called: S2 line.