A dental crown serves as a complete cap, fully encasing a damaged or weakened tooth to restore its shape, strength, and appearance. This prosthetic restoration is bonded onto the prepared tooth structure, shielding it from fracture and decay while allowing it to function normally. Despite being designed as a long-term solution, crowns occasionally become loose or need to be deliberately removed by a dental professional. When this happens, patients often wonder if the existing crown can be reattached.
Is Reattaching an Existing Crown Possible
The direct answer is that reattaching an existing dental crown is often possible, but its success is highly conditional. A dentist can frequently clean the crown and the tooth, then bond the restoration back into place using a fresh layer of permanent dental cement. The feasibility of this procedure depends entirely on the physical condition of the crown, the health of the underlying tooth, and the specific event that caused it to become loose or dislodged. Any attempt at a do-it-yourself fix with non-dental adhesives should be avoided due to the risk of damaging the exposed tooth or crown.
Why Crowns Need to Be Removed
Crowns typically need to be removed or fall off due to a failure of the bond or a new issue developing beneath the restoration. The most common cause is the breakdown of the dental cement over time, which weakens the seal and allows the crown to become loose, especially as the crown approaches the end of its typical lifespan. A more serious reason for removal is the development of secondary decay at the margin, where the crown meets the natural tooth structure near the gumline. Bacteria can enter through this compromised margin, eroding the underlying tooth material needed to hold the crown securely. Dentists may also intentionally remove a crown to gain access for necessary internal procedures, such as a root canal treatment or a repair to a fractured core build-up.
Evaluating the Crown for Reuse
Before re-cementation can occur, the dentist must evaluate both the crown and the tooth structure to ensure a lasting and protective restoration. The integrity of the crown is assessed for any chips, cracks, or warping that may have occurred since its initial placement. If the margins (the edges that wrap around the prepared tooth) are compromised, the crown will not be able to create a tight, bacterial-proof seal and must be replaced.
The underlying tooth structure must also be examined for sufficient healthy material to provide adequate retention. If extensive new decay or a fracture has reduced the height or bulk of the prepared tooth, the crown may no longer have enough surface area to bond. The dentist must also ensure that the crown still seats precisely against the prepared tooth surface without any gaps or rocking motions. A poor margin fit, even after cleaning, would allow oral fluids and bacteria to seep in, making a new restoration necessary to prevent future decay.
The Re-cementation Process
Once the crown is confirmed as reusable, the re-cementation process begins with cleaning the crown’s interior and the prepared tooth. All traces of old dental cement, debris, and bacterial contamination must be thoroughly removed from the crown and the remaining tooth structure. The tooth is then isolated and prepared, which may involve a light etching or conditioning step to improve the adhesion of the new cement.
The selection of the permanent dental cement, also known as a luting agent, is based on the crown material and the clinical situation. Options include resin-modified glass ionomer cements (RMGIC), which offer fluoride release, or stronger resin cements that provide excellent bond strength, particularly for ceramic crowns. The chosen cement is applied to the internal surface of the crown, which is then firmly seated onto the prepared tooth. After the excess cement is cleaned away from the margins, the patient is advised to avoid chewing sticky or hard foods for about 24 hours to allow the cement to fully set and cure.