SMILE-FX® / Narrow Smile Guide
Visible tooth display and the spaces beside a smile
A narrow or wider-looking smile description can concern how much tooth display fills the opening between the mouth corners. The visible tooth span and the lateral spaces beside it describe that display; the opening itself is a separate reference.
Two supplied descriptions
Fuller tooth display within the same opening
Compare descriptions A and B of a proposed look. These are text descriptions, rather than records of a person's treatment.
Same opening. A and B keep the same boundaries at the inside mouth corners.
Larger visible tooth span in B. B explicitly describes a greater span between the last visible teeth on the two sides.
Smaller lateral spaces in B. B also explicitly describes smaller spaces beside the visible teeth within that opening.
What this tells you
B depicts fuller lateral tooth display within the same opening. The authors' formal smile-width measurement stays unchanged: its references are the inside mouth corners, which have not changed in these descriptions.
The stated display difference is meaningful even though that mouth-corner measurement is unchanged. Both the larger tooth span and smaller side spaces are supplied here; one distance or an uncontrolled photograph would not supply the whole description.
The opening and the visible teeth are different references
The smile opening
The study defines its smile-width endpoint between the inside corners of the mouth. This names the opening's two references.
The visible tooth span
The study separately defines the distance between the last visible tooth on each side. These are tooth-display references within the smiling view.
The lateral spaces between the mouth corners and the last visible teeth are called buccal corridors. They sit beside the visible teeth, rather than between neighbouring teeth.
Keeping the references separate helps explain a wider-looking display goal. A description can supply a larger tooth span inside the same opening without describing an increase in the study's formal mouth-corner width.
Where these terms come from
The definitions are adapted from a 2024 retrospective fixed-bracket study. Here they help explain the wording of a display goal. They do not establish an aligner response, a preferred appearance or an individual's result. Read the complete source context and credit.
Your goals, your conversation
Connect the description with your own priorities
At SMILE-FX®, board-certified orthodontists see every patient, including follow-ups. Full-service digital orthodontics has a clear-aligner focus. Your doctor connects individual findings, proposed goals and care arrangements; an illustration helps discuss an intention.
Understanding the description does not require wanting a different appearance. If you are a teen, your priorities and a supporter you choose can be part of that conversation.
Already receiving care? Use your responsible treating team's supplied contact route and instructions. The new-consultation request below is separate from current-care help.
Request a free in-person orthodontic consultation
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Consultation link: https://www.smile-fx.com/lp/free-consult/?utm_source=narrow-smile-guide&utm_medium=microsite&utm_campaign=smile-fx-guides
Source and adaptation
Adapted by SMILE-FX® from Sarah Bühling, Sabrina Schmied, Sara Eslami, Silvia Brandt, Nicolas Plein, Stefan Kopp and Babak Sayahpour, Changes in the arch width and buccal corridor after fixed orthodontic treatment with Damon self-ligating system: premolar extraction vs. non-extraction, Dental Press Journal of Orthodontics, 2024;29(3):e2423159. Original article and DOI 10.1590/2177-6709.29.3.e2423159.oar · CC BY 4.0.
Selected definitions simplified and reorganized, with an original text explanation added. Full context, changes and licence terms. Reference does not imply endorsement.