Crown lengthening is a minor surgical procedure performed by a dental specialist that involves reshaping the gum tissue and, often, the underlying bone structure. The procedure exposes more of the natural tooth surface for two primary purposes: functional, to ensure the success of a dental restoration, or aesthetic, to improve the appearance of the smile.
When Crown Lengthening Is Functionally Required
The most frequent reason for performing crown lengthening is to ensure a stable foundation for a restorative procedure, such as placing a crown or a large filling. This necessity often arises from a violation of the biological width, which is the natural distance between the alveolar bone crest and the base of the gum tissue attachment. This space, typically about 2.04 millimeters, must remain undisturbed to prevent chronic inflammation. If decay, a fracture, or an old restoration margin extends too deep below the gum line, it encroaches upon this biological width.
When the biological width is violated, the body attempts to re-establish the proper distance, resulting in chronic gingival inflammation, bleeding, and eventual bone loss. Crown lengthening surgically moves the gum and bone away, creating the required space for the new restoration margin to sit above the bone. The procedure is also necessary when insufficient sound tooth structure remains above the gum line to securely hold a new crown. A minimum height of tooth structure, sometimes called the ferrule effect, provides adequate retention and resistance form, preventing the final crown from failing.
By exposing more tooth structure, the procedure provides the dentist with better access to remove decay or smooth a fracture line. This access is necessary for making an accurate impression and seating a well-fitting final restoration. In functional scenarios, the procedure is often necessary for saving the tooth from extraction and preventing periodontal disease. The goal is to establish a predictable tooth-to-gum relationship that supports the new restoration.
Using Crown Lengthening for Aesthetic Improvement
Crown lengthening is frequently used as an elective procedure to correct a “gummy smile,” or excessive gingival display. This occurs when an abnormal amount of gum tissue covers the teeth, making them appear short or square, even if the underlying teeth are normal. The condition often results from altered passive eruption, where the gum tissue fails to recede to its appropriate position near the cemento-enamel junction during development.
The aesthetic application also addresses uneven gum lines, where the gingival height of adjacent teeth is asymmetrical, creating an unbalanced smile. By re-contouring the gum tissue and underlying bone, the procedure reveals the full height of the teeth and creates a symmetrical smile line. This surgical repositioning can be performed on a single tooth or across the entire visible smile.
In cases requiring only soft tissue removal, the procedure is termed a gingivectomy. However, true crown lengthening often includes the removal of a small amount of bone (osseous reduction) to ensure the gum tissue remains stable in its new position. Without osseous reduction, the gum tissue can attempt to grow back to its original height, compromising the long-term aesthetic result. When performed for cosmetic reasons, the procedure focuses on achieving balance and proportion.
Understanding the Procedure and Healing Process
The crown lengthening procedure is performed under local anesthesia, ensuring the area is numb and the patient remains comfortable. The specialist, often a periodontist, begins by making small incisions to separate the gum tissue from the tooth and underlying bone. This creates a flap of gum tissue that is gently lifted back to provide visibility of the root surface and the crest of the alveolar bone.
The surgeon removes a small amount of gum tissue (gingivectomy) and, if necessary, re-contours the bone surrounding the tooth root (osteoplasty or osseous surgery). This bone reshaping re-establishes the biological width or ensures the aesthetic stability of the new gum line. Once the required tooth structure is exposed, the gum tissue flap is repositioned and secured with sutures.
The initial healing phase, where swelling and discomfort are most noticeable, typically lasts seven to ten days. Patients manage discomfort with prescribed or over-the-counter pain medication and apply ice packs to minimize swelling, which usually peaks within the first 48 hours. A soft diet is recommended during the first week. Patients must avoid brushing the surgical site directly, often using an antiseptic rinse to keep the area clean.
Sutures are typically removed around one to two weeks after surgery, but the gum tissue requires much longer to fully mature and stabilize. Complete soft tissue healing and bone remodeling can take six to twelve weeks, and sometimes up to six months, especially if bone was removed. Dentists must wait for this full tissue maturation before placing the final crown or permanent restoration. This waiting period ensures the restoration margin will not become exposed if the gums recede slightly during the final stages of healing.
Other Treatment Options
For functional issues like deep decay or fractures, one alternative to crown lengthening is extracting the compromised tooth. The tooth can then be replaced with a dental implant or a fixed bridge. While extraction avoids surgery on the natural tooth, it is a more invasive and permanent solution that removes the option of retaining the natural tooth structure.
Another alternative for restoring a tooth with a subgingival defect is deep margin elevation. This procedure uses advanced adhesive techniques to build up the tooth structure above the gum line before placing a crown. This re-establishes a healthy margin without surgically altering the gum and bone. For aesthetic concerns, an orthodontic procedure known as forced eruption can slowly move the tooth and its surrounding bone and gum tissue outward.
In some cosmetic cases, a less-invasive gingivectomy, which only removes excess gum tissue without touching the bone, may be sufficient for minor contouring. However, without bone reduction, there is a greater risk of the gum tissue growing back. Veneers or composite bonding can also be used to make teeth appear longer or to mask minor gum line asymmetries.