A dental crown is a fixed prosthetic cap placed over a tooth to restore its shape, size, strength, and appearance. When adults with existing crowns seek orthodontic treatment, the presence of this restorative work introduces a significant challenge. The methods used to move natural teeth do not directly apply to the crown’s surface. Achieving successful orthodontic movement requires careful planning and specialized techniques to ensure both alignment success and the integrity of the restoration, demanding a coordinated approach between the general dentist and the orthodontist.
Straightening Teeth with Existing Crowns
It is possible to move a tooth that has a crown, but this process requires specialized planning compared to moving a natural tooth. Orthodontic movement shifts the tooth root within the jawbone, meaning the entire unit—the crown, underlying tooth structure, and root—must move together. The crown, being firmly secured, moves along with the tooth root just like natural enamel.
The primary challenge lies in attaching braces, as different crown materials present varying levels of difficulty for bonding a bracket. Porcelain crowns, whether full ceramic or fused to metal, require a different bonding method than natural enamel to achieve a strong, reliable attachment. In some cases, the orthodontist may opt for alternative methods, such as orthodontic bands that wrap around the tooth, instead of bonding a bracket directly to the crown.
Adhesion Protocols and Bracket Placement
Specialized adhesion protocols are the core technical solution for straightening crowned teeth, as traditional bonding agents are ineffective on prosthetic surfaces like porcelain or metal. The smooth, non-porous nature of these materials prevents the micro-mechanical interlocking necessary for bonding to natural enamel. Therefore, the crown must undergo specialized preparation to create a reliable surface for the bracket adhesive.
For porcelain surfaces, preparation often involves micro-etching or sandblasting with aluminum oxide particles (air abrasion) to create microscopic roughness. This mechanical roughening is often followed by applying a chemical agent, such as a silane coupling agent, which chemically links the ceramic material to the acrylic bonding resin used for the bracket. This multi-step preparation is necessary to achieve a bond strength comparable to natural enamel, preventing the bracket from de-bonding during treatment. Upon completion, the orthodontist must use a gentle technique, often applying a peel-type force, to remove the bracket without fracturing the crown.
Optimal Treatment Sequencing
The ideal approach for patients requiring both crowns and orthodontic treatment is to move the teeth into their final, corrected positions first. This sequencing allows the orthodontist to achieve ideal alignment and bite relationship before the final restorative work is done. Once the teeth are straightened, the general dentist places the final crowns, ensuring they fit perfectly within the newly established bite. This plan eliminates the need to bond to a prosthetic surface and guarantees the crown’s shape and size are proportional to the corrected smile.
If a patient already has existing final crowns, the orthodontist must evaluate whether they will remain aesthetically or functionally appropriate after the teeth move. Often, existing crowns need to be reshaped or entirely replaced to align with the new tooth position. If a crown is required before treatment starts, a temporary crown can be placed. This temporary crown is less costly and can be easily replaced with a final, properly contoured crown once the teeth are straight, avoiding restorative work that would otherwise need to be redone.
Alternatives When Orthodontic Movement Is Not Advised
When existing crowns are extensive, or the risk of damaging the restoration is too high, non-orthodontic solutions can achieve a straighter appearance. Full orthodontic movement may be contraindicated if the underlying tooth structure is compromised or if the patient is unwilling to replace the crown afterward. These alternatives focus on cosmetic changes to the crown itself rather than moving the tooth root.
For minor alignment issues, the existing crown can sometimes be cosmetically contoured through subtle reshaping and polishing to create the illusion of straightness. A more definitive cosmetic solution is replacing the existing crown with a new one custom-designed to align perfectly with adjacent teeth. Crowns or porcelain veneers can mask mild to moderate misalignment, creating a straight facade without braces or aligners. While this provides an immediate cosmetic result, it is purely an aesthetic fix and does not correct the underlying position of the tooth root.