A dental crown is a tooth-shaped cap placed over a damaged or weakened tooth, restoring its shape and strength. This restoration fully encases the entire visible portion of the tooth. Crowns are secured to the underlying tooth structure using specialized dental cement, providing stability for chewing and improving the tooth’s appearance. While crowns typically last between five and 15 years, the bond securing them can sometimes fail, causing the crown to become loose or fall out. Understanding the factors that cause this failure and implementing consistent maintenance practices are the most effective ways to maintain the security of your restoration.
Why Crowns Become Loose
The most frequent cause of crown failure is the degradation of the dental cement used to bond the restoration to the tooth. Over time, exposure to saliva and the constant forces of chewing can cause this adhesive material to wash out or weaken, compromising the seal. Once the cement bond is degraded, the crown loses its grip on the prepared tooth structure beneath it.
Another common issue involves the development of decay underneath the crown itself. Although the crown material is resistant to decay, the underlying tooth structure remains susceptible to bacterial acid erosion, usually near the gumline where the crown meets the tooth. As decay progresses, it changes the shape of the supporting tooth, shrinking the structure the crown is meant to fit over. This loss of internal tooth volume makes the crown loose, regardless of the strength of the remaining cement.
Excessive mechanical force also contributes significantly to a crown becoming dislodged. Habits like teeth grinding or clenching, known as bruxism, place intense, repeated pressure on the restoration. These forces can fracture the crown material or weaken the cement bond, causing the restoration to pop off. A sudden impact or trauma to the mouth can also directly disrupt the bond holding the crown in place.
The consistent strain from biting certain foods can pull a crown loose over time. Sticky and chewy items, such as caramels or gummy candies, generate a strong adhesive force that tugs at the margin of the crown. This pulling action slowly strains and eventually breaks the seal provided by the dental cement.
Immediate Action When a Crown is Loose or Falls Out
If a crown becomes loose or completely falls out, remain calm and immediately retrieve the restoration. Rinse the crown gently with water to remove debris and store it safely in a clean container or small plastic bag. Inspect the crown for damage and examine the exposed tooth beneath it.
The exposed tooth structure is vulnerable to sensitivity and further damage. Contact your dental office immediately to schedule an appointment for re-cementation, explaining that the crown has come off. Prompt attention is necessary because the tooth can shift quickly without the crown, making re-fitting more difficult later.
If you cannot see a dentist immediately, attempt a temporary fix to protect the exposed tooth and manage sensitivity. Over-the-counter temporary dental cement, available at most pharmacies, is the preferred method for reattaching the crown until your appointment. Clean the inside of the crown and the tooth, apply a small amount of the temporary cement inside the crown, and gently seat it back onto the tooth.
If temporary dental cement is unavailable, a small amount of petroleum jelly or toothpaste can be used as a makeshift adhesive to hold the crown in place for a few hours. This is a last resort to reduce sensitivity until you can secure proper temporary dental adhesive. Avoid using household glues, as these are toxic and can permanently damage the tooth and the crown.
Chew food exclusively on the opposite side of your mouth to prevent dislodging the crown or damaging the vulnerable tooth. If the exposed tooth surface has sharp edges, place a small amount of dental wax over it to protect the soft tissues of the mouth.
Preventative Habits for Crown Longevity
Maintaining a dental crown involves mindful habits and consistent professional care. Modifying dietary choices minimizes stress on the restoration.
Dietary Adjustments
Avoid chewing on excessively hard foods, as these can crack the crown or break the adhesive seal. Limit sticky or chewy foods, such as taffy, caramel, or gum, to prevent the crown from being pulled off the prepared tooth. When eating, distribute the chewing load across both sides of the mouth rather than concentrating all the force onto the crowned tooth.
Oral Hygiene
Meticulous oral hygiene is instrumental in preventing the decay that can loosen a crown. Brush twice daily with a soft-bristled toothbrush and fluoride toothpaste, paying particular attention to the margin where the crown meets the gumline. Flossing daily is equally important; use floss threaders or interdental brushes to thoroughly clean the area beneath the crown’s contact point and the adjacent tooth.
Managing Bruxism
For individuals who experience teeth grinding or clenching, a custom-fitted nightguard is highly recommended. This appliance mitigates the excessive pressure placed on the crown during sleep, protecting the restoration and the surrounding teeth from fracturing or becoming loose.
Regular Professional Check-ups
Regular check-ups with a dental professional are necessary for proactively assessing the integrity of the crown. During these visits, the dentist examines the crown’s fit, checks the margins for signs of cement washout, and identifies any early decay beneath the restoration. Professional assessment and cleaning maximize the lifespan of any dental restoration.