A dental crown is a custom-made cap placed over a damaged tooth to restore its shape, size, strength, and appearance. Gum recession occurs when the gum tissue surrounding a tooth wears away or pulls back, exposing the tooth’s root surface. When these two conditions meet, they present a common concern regarding the crown’s long-term function and stability. This article explores the relationship between dental crowns and receding gums, detailing the consequences and available solutions.
Understanding Gum Recession and Crown Margins
A dental crown can remain on a tooth that has experienced gum recession, but this change significantly alters the interface between the restoration and the natural tooth. Recession occurs due to factors like aggressive toothbrushing, periodontal disease, genetic predisposition, or the natural aging process. The crown margin is the line where the edge of the dental crown meets the prepared tooth structure.
When the gums recede, this margin, which was initially placed near or beneath the gumline for a seamless fit, becomes exposed. Recession also reveals the underlying root surface of the natural tooth, which the crown does not cover. The exposed margin indicates that the crown’s original design is no longer optimized for the current oral environment, potentially leading to various oral health complications.
The underlying root structure exposed by recession is covered in cementum, unlike the tooth’s enamel crown. Cementum is much softer than enamel, making the exposed area vulnerable. This vulnerability is compounded because the exposed junction is more difficult to keep clean. A poorly fitting crown or an exposed margin can also irritate the gum tissue, potentially leading to further inflammation and recession.
The Functional and Aesthetic Implications
The exposure of the crown margin and underlying root surface introduces both functional and aesthetic issues. One immediate functional problem is increased tooth sensitivity, particularly to hot, cold, or sweet stimuli. This occurs because the exposed root is covered by dentin and cementum, which are less dense than enamel and transmit sensations more readily to the nerve tissue.
A more serious concern is the elevated risk of root surface decay, or secondary caries. Since cementum is softer and more porous than enamel, it is highly susceptible to bacterial acid erosion. Plaque tends to accumulate in the small gap created by the exposed margin, making it a prime site for decay to begin and spread quickly beneath the crown. This decay compromises the remaining tooth structure and can ultimately lead to crown failure.
Receding gums also create significant aesthetic problems, especially when the affected tooth is visible. If the crown is an older porcelain-fused-to-metal (PFM) type, recession often exposes the dark metal substructure, creating a noticeable “dark line” at the gumline. Even with all-ceramic crowns, the tooth appears visibly longer than adjacent teeth, and the exposed root can have a yellowish tint, causing a color mismatch.
Treatment Approaches for Exposed Margins
Addressing problems caused by receding gums requires an approach tailored to the severity of the recession and the health of the underlying tooth. For minor recession where the crown margin is intact and the root is healthy, dentists may manage sensitivity using desensitizing agents, varnishes, or bonding materials to seal the exposed dentin and cementum. These non-surgical options protect the vulnerable root surface and reduce discomfort.
If the recession is moderate to severe, or if the underlying tooth has developed decay, a more involved restorative procedure is necessary. A common solution is replacing the existing crown with a new one custom-designed to fit the new, lower gumline. Choosing an all-ceramic or zirconia crown for replacement eliminates the risk of dark metal exposure, significantly improving the aesthetic outcome. The new crown’s margin is positioned to follow the receded gumline, ensuring a tight seal.
When recession is extensive and aesthetics or sensitivity remain problematic, a periodontal intervention may be recommended. Gum grafting is a surgical procedure performed by a specialist to restore lost gum tissue and cover the exposed root surface. A successful graft improves the tooth’s appearance, eliminates sensitivity, and provides renewed protection for the root surface, enhancing the crown’s long-term success.