The appearance of gum tissue above the upper teeth while smiling is a common aesthetic concern known as excessive gingival display, or a “gummy smile.” This characteristic is a natural variation in facial anatomy that results in more gum tissue being exposed than is typical. While many people are comfortable with this look, others seek cosmetic solutions for a more balanced smile. The underlying reasons involve the structure of the jawbone, the positioning of the teeth, and the movement of the upper lip.
Determining Excessive Gum Display
Dental professionals quantify a smile’s aesthetic balance by measuring the amount of gum tissue visible during a full, natural smile. A normal smile generally exposes only one to two millimeters of gingiva above the upper teeth. When two millimeters or more of gum tissue is visible, it is classified as an excessive display. Display exceeding four millimeters is frequently regarded as unaesthetic and prompts patients to seek treatment.
The assessment begins by observing the teeth and gums at rest before analyzing the dynamic smile. The clinician evaluates the upper lip’s movement and the height it reaches during a full expression, defining the “smile line.” A high smile line shows the entire tooth crown along with excessive gum tissue. This contrasts with a standard smile line that exposes only the crowns and minimal gingiva.
The Primary Structural Causes
The underlying reason for an excessive gum display can be categorized into three main structural areas: muscular activity, dental and gingival architecture, and skeletal positioning. Accurately identifying the specific cause is necessary because it directly dictates the most appropriate treatment pathway. It is not uncommon for a person to have a combination of these factors contributing to the appearance of their smile.
Muscular Activity
One common cause is the hyperactivity of the muscles responsible for elevating the upper lip when a person smiles. This muscular variation results in a hypermobile lip that lifts higher than usual, uncovering an excessive amount of the gum tissue underneath. The specific muscles involved include the levator labii superioris alaeque nasi (LLSAN) and the levator labii superioris (LLS). When these lip elevator muscles contract too forcefully, they create a wider vertical opening, exposing the gingiva.
Dental and Gingival Architecture
This category involves the actual structure and positioning of the teeth and surrounding gum tissue. Altered Passive Eruption (APE) occurs when the gums fail to recede fully to their proper final position after the tooth has completed its eruption process. This leaves excess gum tissue covering the tooth’s crown, making the teeth appear shorter and creating a disproportionate gum-to-tooth ratio. Gingival hyperplasia is a related issue, marked by an overgrowth of gum tissue linked to genetics, certain medications, or chronic inflammation.
Skeletal Positioning
The third cause is the skeletal structure, specifically the vertical dimension of the upper jawbone, or maxilla. This condition is termed Vertical Maxillary Excess (VME) and is characterized by an overgrowth of the maxilla, causing the upper teeth and gums to project too far downward. VME is a frequent cause of a “gummy smile” and can result in an elongated appearance to the lower third of the face.
Corrective Options for Gummy Smiles
Treatment for excessive gingival display depends on accurately diagnosing the underlying cause, ranging from non-surgical options to comprehensive surgical procedures.
Muscular Hyperactivity Treatment
For cases related to muscular hyperactivity, where the lip moves too high, a neurotoxin injection, such as Botulinum Toxin (Botox), offers a temporary solution. The toxin is injected into the lip elevator muscles to temporarily weaken them, limiting the upward movement of the upper lip during a smile. This effect typically lasts between three to six months, requiring repeat treatments.
Gingival Reshaping
When the cause is related to excess gum tissue or Altered Passive Eruption, procedures focused on reshaping the gingiva are used. A gingivectomy involves removing the excess gum tissue to expose the full length of the tooth’s natural crown. If the underlying bone contributes to the issue, crown lengthening is performed, which involves reshaping both the gum tissue and the bone surrounding the tooth. These periodontal surgical approaches offer a permanent correction.
Skeletal and Alignment Correction
For issues related to tooth alignment or mild skeletal discrepancies, orthodontic treatment can reposition the teeth within the jawbone. Orthodontics, sometimes utilizing temporary anchorage devices (TADs), can push the upper front teeth and gums higher into the maxilla, reducing the vertical display. The most involved treatment is orthognathic surgery, or jaw surgery, reserved for severe cases of Vertical Maxillary Excess. This procedure involves a maxillofacial surgeon physically repositioning the entire upper jaw to a higher level, providing a permanent correction for the underlying skeletal disproportion.