A gummy smile is a common cosmetic concern where a noticeable amount of gum tissue shows above the upper teeth during a full smile. Showing more than two to three millimeters of gingiva typically qualifies a smile as “gummy.” This characteristic stems from underlying anatomical and muscular factors affecting the relationship between the lip, teeth, and gums. Understanding the cause is the first step toward finding a successful solution.
The Genetic Link to Gummy Smiles
The inheritance of a gummy smile is complex, tied not to a single gene but to a collection of genetically determined physical traits. Skeletal structure and muscle strength are passed down, predisposing an individual to excessive gingival display. The condition is often polygenic, resulting from the cumulative effect of multiple genes.
One significant inherited factor is the hyperactivity of the upper lip muscles. If these muscles move the lip excessively, a hypermobile lip results, revealing more gum tissue when smiling.
Another major cause is Vertical Maxillary Excess (VME), the vertical overgrowth of the upper jawbone (maxilla). This skeletal pattern causes the upper dental arch and gum line to sit too low. Inherited tooth morphology can also contribute, specifically short clinical crowns where gum tissue has not receded properly.
Structural Causes Beyond Inheritance
Not all instances of excessive gum display are genetic; many structural causes are developmental or acquired. A common developmental issue is delayed passive eruption, where the gingiva fails to recede completely to the cementoenamel junction (CEJ). This leaves excess gum tissue covering the teeth, making them look abnormally short.
Another structural cause is medication-induced gingival hyperplasia, where certain pharmacological agents cause the gum tissue to swell and overgrow. Medications such as anticonvulsants and immunosuppressants can trigger an inflammatory response that increases the bulk of the gingiva.
Compensatory eruption (dentoalveolar extrusion) also leads to excessive gingival display. This occurs when the teeth over-erupt to compensate for severe wear or a missing opposing tooth, pushing the gum line further down. The bone and gum tissue follow the teeth, resulting in a lower occlusal plane.
Treatment Options for Excessive Gum Display
Effective treatment depends on accurately diagnosing the underlying cause, ranging from soft tissue issues to complex skeletal problems. For delayed passive eruption or mild gingival overgrowth, minimally invasive procedures are often sufficient. Gum contouring (gingivectomy) surgically removes excess gum tissue to expose the full anatomical length of the tooth crown.
If the cause is a hyperactive upper lip muscle, non-surgical options like Botulinum Toxin (Botox) injections can be used. Botox temporarily weakens the lip elevator muscles, limiting how high the upper lip rises during a smile and reducing the gum display for several months.
For moderate cases involving the teeth and alveolar bone, orthodontic solutions are implemented. Temporary anchorage devices (TADs) can physically push the teeth and surrounding bone upward into the maxilla. Severe cases, particularly those involving Vertical Maxillary Excess, require orthognathic surgery to surgically reposition the entire upper jaw higher into the facial skeleton.