Excessive gingival display, commonly referred to as a “gummy smile,” is an aesthetic concern defined by the overexposure of the gum tissue above the upper teeth when a person smiles fully. While one to two millimeters of gum showing is considered normal, the display becomes excessive when more than two to three millimeters of gingiva is visible. This presentation is generally not a medical problem but is a frequent reason individuals seek cosmetic dental or surgical consultation.
The Anatomical Reasons for Excessive Gum Display
The underlying causes for an excessive gum display are varied and typically fall into three broad anatomical categories: skeletal structure, muscular activity, and the dentogingival complex. Often, a combination of these factors is present, making a thorough diagnosis necessary to determine the correct treatment approach.
One common structural cause is Vertical Maxillary Excess (VME), which involves an overgrowth of the upper jaw bone, or maxilla, in the vertical plane. When the maxilla grows too far downward, the entire arch of the upper teeth and their supporting gum tissue are positioned lower in the face. This skeletal discrepancy results in the gums being more visible even when the lips are relaxed, and significantly more so during a smile.
Another factor is the hyperactivity of the upper lip muscles, which causes the lip to lift too high during a full smile. The primary muscle responsible for this is the levator labii superioris alaeque nasi (LLSAN), sometimes referred to as the muscle that causes the characteristic “Elvis snarl.” When this muscle contracts excessively, it pulls the upper lip well above the tooth crowns, revealing the underlying gum tissue. A short upper lip length can also contribute to this problem, as there is less tissue available to cover the gum line even with normal muscular movement.
The third major category relates to the teeth and surrounding gum tissue itself, referred to as the dentogingival complex. Altered Passive Eruption (APE) is a condition where the gum tissue fails to recede fully to its correct position after the tooth has emerged, leaving a layer of gum covering part of the natural tooth crown. This makes the teeth appear shorter and squarer, and the gum line appears lower and more prominent, resulting in a disproportionate amount of visible gum. Excessive growth of the gum tissue, known as gingival hyperplasia, also contributes to a gummy appearance, especially when caused by certain medications or inflammation.
How Dental Professionals Evaluate Gummy Smiles
Dental professionals begin the diagnostic process by carefully assessing the patient’s smile dynamics and facial proportions. They measure the exact amount of gingiva visible during a full, natural smile; measurements exceeding three to four millimeters are often considered excessive. This objective measurement helps classify the severity of the display.
The length and movement of the upper lip are also analyzed, both when the lip is at rest and when fully elevated during smiling. Clinicians determine whether the lip is physically short or if the issue is a hyperactive muscular pull, which can move the lip up to ten millimeters from its resting position in severe cases. Furthermore, the proportion of the visible tooth (clinical crown length) is assessed to identify if the teeth themselves appear short, which may point toward altered passive eruption.
To look beyond the soft tissues, specialized imaging techniques are often employed to check the underlying skeletal structure. X-rays, particularly a lateral cephalometric analysis, are useful for confirming a diagnosis of Vertical Maxillary Excess. This imaging allows the practitioner to measure the vertical dimensions of the maxilla relative to the base of the skull and other facial landmarks, ensuring the treatment plan addresses the root cause.
Non-Surgical and Minimally Invasive Corrections
For cases where the excessive gum display is caused by muscular hyperactivity or mild gum overgrowth, less invasive treatments are often the first recommendation. One common non-surgical option is the use of neurotoxin injections, such as Botox, to address the hyperactive lip muscles. The substance is injected into the upper lip elevator muscles, primarily the LLSAN, temporarily weakening their ability to pull the lip too high.
This relaxation of the muscle reduces the upward movement of the lip during a smile, effectively lowering the visible gum line. The procedure is quick, with results appearing within a week, but the effect is temporary, usually lasting three to six months, requiring repeat treatments to maintain the result.
For mild cases of altered passive eruption, a gingivectomy can be performed using a laser or electrosurgery. This procedure involves precisely trimming away the excess gum tissue to expose the full, natural length of the tooth crown.
Orthodontic treatment can also be employed when the excessive gum display is linked to teeth that have over-erupted, a condition known as dentoalveolar extrusion. Braces or clear aligners, sometimes used in conjunction with Temporary Anchorage Devices (TADs), can gently push the upper teeth further up into the jawbone, a process called intrusion. Intrusion effectively reduces the amount of gum tissue that is exposed, shifting the entire gum line higher without requiring soft-tissue removal.
Surgical and Comprehensive Solutions
For more structurally involved or severe cases, surgical interventions are necessary to achieve a permanent correction. When altered passive eruption involves excessive bone surrounding the tooth, a procedure known as crown lengthening surgery is performed. This procedure, often done by a periodontist, involves removing not only the excess gum tissue but also a small amount of the underlying bone. Removing the bone ensures the gum margin heals in a stable, higher position, permanently exposing the full anatomical tooth crown.
The most comprehensive intervention is orthognathic surgery, or jaw surgery, which is reserved for cases caused by severe Vertical Maxillary Excess. This involves an oral and maxillofacial surgeon physically repositioning the entire upper jaw higher into the skull base. Moving the maxilla upward corrects the skeletal disproportion and provides a permanent correction for the underlying deformity.