A dental crown is a restorative cap placed over a damaged tooth to restore its shape, size, and strength. Gingival recession, commonly known as receding gums, is the process where gum tissue pulls back, exposing more of the tooth or its root. Having both a dental crown and receding gums is common, especially in adults. This combination creates unique challenges that require prompt attention from a dental professional.
What Happens When Gums Recede Around a Crown
When gum tissue recedes, the structure of the tooth and crown becomes visibly altered. The gum line drops below the crown’s margin, the precise edge where the restoration meets the natural tooth structure. This exposure of the margin, which was once tucked just under the gum line, is the first and most obvious change.
This retraction exposes the underlying tooth root surface, which is made of dentin and cementum, unlike the hard enamel covering the crown. For crowns made with a metal substructure, often called porcelain-fused-to-metal (PFM) crowns, recession can expose the dark metal collar. This results in a noticeable gray or black line right at the gum-tooth interface, creating an aesthetic concern.
The visible area of the tooth appears elongated or “longer” because the protective gum tissue no longer covers the root. This exposed surface is not designed to withstand the oral environment like the crown or enamel. This structural change compromises the seamless fit between the restorative material and the gum tissue.
The Health Risks of Exposed Crown Margins
The newly exposed root surface and crown margin introduce issues that compromise oral health. Increased tooth sensitivity is a consequence because the root surface is covered by cementum and dentin, which are softer than enamel. Dentin contains thousands of microscopic tubules that lead directly to the tooth’s nerve, causing pain when exposed to hot, cold, or sweet stimuli.
The exposed root is more vulnerable to decay than the enamel-covered crown surface. Root surfaces are softer and more porous, making them easier targets for acid-producing bacteria to cause root surface decay. This decay can progress silently underneath the crown, often difficult to detect until it becomes a major problem.
The exposed margin creates an irregular ledge difficult to clean with routine brushing and flossing. This area can become a breeding ground for plaque and bacteria, leading to chronic gum inflammation and periodontal disease. If the seal between the crown and the tooth is compromised by recession or decay, bacteria can leak underneath the restoration, leading to internal decay and potentially structural failure of the tooth.
Treatment Options for Gum Recession Near Crowns
Addressing gum recession near a crown involves interventions ranging from minor restorative adjustments to surgical procedures. For mild cases focused on sensitivity, a dentist may apply desensitizing agents or use dental bonding material to cover the exposed root surface. This resin material is sculpted to fill the gap and protect the vulnerable dentin, though it does not restore the lost gum tissue.
When recession is more pronounced or causes health risks, the solution is often periodontal surgery, specifically a gingival graft. This procedure involves transplanting tissue, often taken from the roof of the mouth, onto the area of recession to restore the gum line. The goal of grafting is to cover the exposed root, reduce sensitivity, and protect the tooth from root decay, effectively restoring the biological barrier.
If the existing crown is old, poorly fitted, or its margin is exposed, replacement may be necessary. A new crown can be designed with a margin that extends further down to better accommodate the new, lower gum line or to cover the exposed root. Replacing a porcelain-fused-to-metal crown with an all-ceramic option can also eliminate the aesthetic issue of the dark metal line that becomes visible when gums recede.