A dental crown is a fixed cap that a dentist permanently bonds over a damaged or weakened tooth, covering the portion visible above the gum line. This restoration mimics the shape, size, and strength of a natural tooth, providing protection and restoring function. While crowns are durable, they are not permanent and may require removal over time. Detaching a cemented crown is a precise procedure involving specialized tools and techniques to ensure the underlying tooth structure remains intact.
Reasons for Removing a Dental Crown
The primary reason a crown must be removed is secondary decay, which occurs when bacteria penetrate the seal where the crown meets the natural tooth structure, often near the gum line. Even a microscopic gap allows oral bacteria and acids to seep in, leading to active decay beneath the prosthetic. This decay compromises the underlying tooth, known as the abutment, and requires the crown’s removal for treatment.
Structural failures of the crown itself also necessitate replacement, such as a fractured porcelain face or a crack in the metal substructure. Damage to the crown’s integrity can expose the tooth to further harm or create rough surfaces that irritate the surrounding gum tissue. Furthermore, failure of the luting cement, the adhesive material used to bond the crown, can cause the restoration to feel loose or shift slightly.
Another common indication is the need for endodontic treatment, or a root canal, on the crowned tooth. Since the crown covers the entire tooth, the dentist must remove it to gain access to the pulp chamber and root canals for treatment. Crowns may also be replaced for aesthetic reasons, such as updating an older restoration to better match adjacent teeth, or due to an improper initial fit that caused alignment or bite problems.
Professional Methods and Techniques
Dentists approach crown removal using techniques classified as either non-destructive or destructive, depending on whether the goal is to save the existing crown for reuse or replacement. Non-destructive methods are preferred when the crown is structurally sound and only needs temporary removal for access or recementation. These techniques focus on breaking the bond of the luting cement without damaging the crown material.
Specialized instruments apply either vibration or controlled mechanical force to the crown. Ultrasonic crown removers utilize high-frequency vibrations transmitted through a specialized tip to shatter the cement layer without harming the crown or the underlying tooth. Other tools, such as automatic crown removers, employ a spring-loaded mechanism to deliver a short, sharp impulse shock, leveraging the crown off the prepared tooth.
When the crown is heavily bonded, has a metal substructure, or is planned for replacement, a destructive method is employed. This technique involves using a high-speed dental bur to precisely cut a groove through the crown material. The dentist cuts a slot from the chewing surface down to the margin, allowing the crown to be sectioned into pieces and lifted away. Local anesthesia is administered before either technique to ensure patient comfort, especially during the cutting process or if the underlying tooth is sensitive.
What Happens After the Crown is Removed
Once the crown is detached, the focus shifts to assessing the condition of the underlying tooth structure, or the abutment. The dentist examines the exposed tooth for signs of decay, fractures, or cracks that may have been hidden by the crown. Any decayed or compromised tooth material is cleaned and removed to prepare a healthy foundation for the new restoration.
If significant tooth structure was lost due to decay or initial preparation, a core buildup procedure may be necessary to restore the required volume. This buildup uses a composite resin material to provide a stable base that supports and retains the new crown. After repairs and preparations are complete, the dentist takes a final impression of the prepared tooth and the surrounding area. This impression, whether a physical mold or a digital scan, is sent to a dental laboratory to serve as the blueprint for fabricating the permanent replacement crown.
A temporary crown is immediately placed over the newly prepared tooth, secured with temporary cement. This temporary restoration guards the sensitive tooth from temperature changes and bacterial ingress while the permanent one is created. It also prevents adjacent and opposing teeth from shifting, which could compromise the fit of the final crown. Patients are advised to avoid sticky, hard, or chewy foods and to clean the area gently to avoid dislodging the temporary crown before their final placement appointment.