A “dead tooth,” more accurately termed a non-vital tooth, is one that no longer has a living nerve or blood supply within its pulp chamber. This condition frequently occurs after severe trauma or deep decay necessitates a root canal procedure to remove the infected or necrotic tissue. A common consequence of this loss of vitality is a noticeable darkening or discoloration of the tooth structure. While traditional external bleaching methods are ineffective on these internal stains, non-vital teeth can be whitened through a specialized dental procedure that addresses the intrinsic staining from the inside.
Why Dead Teeth Change Color
Discoloration in a non-vital tooth stems from the internal breakdown of tissue following the death of the dental pulp. The core mechanism involves the decomposition of blood components and nerve tissue trapped within the tooth structure. When the blood supply is cut off, the hemoglobin in red blood cells breaks down, releasing iron compounds.
These iron-containing byproducts, such as iron sulfide, are color-producing (chromogenic). The microscopic dentinal tubules, which radiate outward from the pulp chamber into the dentin, absorb these compounds. This penetration results in the tooth taking on shades of gray, brown, or even black.
Discoloration can also be caused by residual materials left behind after root canal treatment. If the endodontic filling material (gutta-percha) or the root canal sealer is not thoroughly cleaned from the crown, it can leach into the dentin. Certain sealers cause staining over time, contributing to the overall dark appearance.
The Internal Whitening Process
The primary method for lightening a discolored non-vital tooth is internal bleaching, also referred to as the “walking bleach” technique. This procedure begins with the dentist gaining access to the pulp chamber, usually by removing the existing restoration from the back of the tooth. The goal is to create a clean reservoir within the tooth’s crown to hold the bleaching agent.
A critical step is the creation of a cervical barrier, a protective seal placed over the root canal filling material. This seal, often made of glass ionomer cement, is positioned approximately two to three millimeters below the cemento-enamel junction. The barrier prevents the potent bleaching agent from leaking down onto the root surface and surrounding bone and gum tissue.
Once the protective barrier is in place, the bleaching agent is introduced into the prepared pulp chamber. Historically, a mixture of sodium perborate and hydrogen peroxide was used, but modern protocols often utilize a concentrated carbamide or hydrogen peroxide gel. The chamber is filled with this gel, and the tooth is then temporarily sealed with a filling.
The term “walking bleach” refers to the fact that the patient leaves the office with the bleaching agent sealed inside, where it works continuously over several days. The patient typically returns within three to seven days for the dentist to evaluate the color change. If the desired shade has not been achieved, the process is repeated until the tooth matches the surrounding teeth.
While internal bleaching is a conservative and effective treatment, a rare but serious potential complication is external cervical root resorption (ECR). This condition involves the breakdown of tooth structure and bone near the gum line. Proper placement of the cervical barrier is paramount to mitigate this risk by preventing the oxidizing chemicals from reaching the external root surface. Once the desired color is reached, the internal bleaching material is removed, and the access cavity is permanently sealed with a tooth-colored filling material.
Alternative Cosmetic Treatments
If internal bleaching is unsuccessful, contraindicated due to structural issues, or if the discoloration is too severe, several alternative cosmetic treatments are available to mask the dark tooth. These options involve covering the discolored tooth surface rather than attempting to lighten the stain itself. These restorative methods are typically more invasive as they require modification to the remaining tooth structure.
Composite Bonding
Composite bonding is the least invasive cosmetic alternative, involving the application of a tooth-colored resin material directly to the front surface of the tooth. The dentist sculpts and polishes the resin to match the surrounding teeth, effectively concealing the gray color. Bonding is a quick and cost-effective procedure, but the material is generally less durable and more susceptible to staining or chipping compared to porcelain restorations.
Porcelain Veneers
Porcelain veneers represent a more durable and aesthetic solution, involving a thin, custom-made shell of porcelain bonded to the front surface of the tooth. The veneer permanently masks severe discoloration and can also correct minor shape or alignment issues. A small amount of enamel is usually removed from the tooth surface to accommodate the veneer and ensure a natural-looking fit and contour.
Dental Crowns
Dental crowns are the most comprehensive restorative option, often chosen when the non-vital tooth is not only discolored but also structurally weakened. A crown fully encases the entire visible portion of the tooth above the gum line. This treatment provides maximum protection and strength, while also completely covering the dark tooth with a custom-made, natural-looking cap.