The gummy smile: usually a muscle,
rarely a surgical problem

What makes a smile 'gummy'

Smile analysis measures gingival display: how much gum shows between the upper lip and the teeth at full smile. Up to about three millimetres reads as youthful and normal; beyond that, the gum line starts to compete with the teeth for attention, and owners of such smiles often train themselves to smile guardedly — a genuine cost, paid daily, for a few millimetres of anatomy.

The mechanisms matter more than the label. A minority of gummy smiles are skeletal (the upper jaw is vertically long) or dental (teeth erupted with too much gum coverage) — those belong with orthodontists, periodontists and maxillofacial surgeons. The majority are muscular: everything is built normally, but the lip elevators contract too enthusiastically, lifting the lip several millimetres higher than average on smiling. That subset — the hypermobile lip — is where injectable treatment shines.

The muscles doing the overwork

Several paired muscles raise the upper lip, and one — the levator labii superioris alaeque nasi, running beside the nose — contributes most to the central gum flash. Polo's work established the injection approach: micro-doses of muscle relaxant placed precisely into the overactive elevators reduce the excess lift while leaving normal smile mechanics intact. The word that matters is excess. The goal is not a weakened smile but a rebalanced one — the lip still rises, the teeth still show, the extra centimetre of gum stays covered.

“The goal is not a weaker smile. It is the same smile, minus the centimetre it never needed.”

Dr Sin YongOn rebalancing rather than freezing

What treatment involves

After smile analysis — in motion, not from a photograph alone — treatment is a handful of tiny injections at mapped points, taking minutes, with no downtime beyond possible pinpoint marks. The effect assembles over days, is reviewed once settled, and lasts months before gradually wearing off. Because the pull is symmetrical by design, dosing respects symmetry too; an asymmetric smile is analysed for which side overpulls and dosed accordingly, which is where experience earns its keep.

Honest limits, and who should look elsewhere

BTX cannot shorten a vertically long maxilla, re-cover teeth that erupted gum-heavy, or lengthen a genuinely short lip — and a doctor should say so at assessment rather than treat everyone who walks in. Marked skeletal cases deserve a dental-surgical opinion; some patients combine approaches. And because muscle-relaxant effects are fully temporary, the muscular version of this treatment carries a built-in safety: if the rebalanced smile is not to your taste, the previous one returns on its own within months.