A root canal procedure is a common dental treatment designed to save a tooth that has been severely damaged due to decay or infection. The procedure involves removing the infected or inflamed pulp from inside the tooth, cleaning and disinfecting the inner root canals, and then filling and sealing them. A frequent concern for individuals undergoing this treatment is the potential for their treated tooth to change color afterward. This article explores why such discoloration can occur and what options exist to address it.
Mechanisms of Tooth Discoloration
Tooth discoloration following a root canal often stems from internal factors. One primary cause involves the breakdown products of blood and necrotic tissue that remain within the dentinal tubules. When the pulp becomes necrotic or is removed, residual hemoglobin can decompose, releasing iron. This iron can then combine with hydrogen sulfide, a byproduct of bacterial metabolism, to form dark-colored iron sulfides that permeate the tooth structure.
Another contributing factor is the presence of remnants of pulp tissue, particularly in the pulp chamber. These microscopic tissues can undergo degradation over time, leading to intrinsic staining of the tooth. Certain root canal filling materials and sealers used during the procedure can also cause discoloration. For example, some older sealers containing eugenol or certain types of silver-containing materials might leach into the dentin, imparting a grey or black tint.
The loss of vitality and blood supply to the tooth, while not directly causing discoloration, can make the tooth appear less translucent and vibrant compared to adjacent healthy teeth. This change in optical properties can contribute to a duller or darker appearance. Additionally, if the pulp chamber is not thoroughly cleaned of all restorative materials or remnants, these elements can also lead to noticeable staining.
Appearance of Discolored Teeth
The discoloration of a tooth after a root canal can manifest in various shades, often differing significantly from the surrounding natural tooth color. Commonly, the affected tooth may appear grey, dark brown, or even yellow-brown. In some instances, it might take on a more pronounced blackish hue. This change in color is typically uniform throughout the tooth, though it can sometimes be more concentrated in specific areas, such as near the gum line or on the biting surface.
The altered shade is an intrinsic discoloration, meaning it originates from within the tooth structure itself, unlike external stains. Consequently, traditional tooth whitening methods are generally ineffective against this type of internal discoloration. The visual contrast between the treated tooth and adjacent healthy teeth can become noticeable, impacting the overall aesthetic appearance of a person’s smile.
Prevention and Remedial Options
Preventative measures during the root canal procedure minimize the risk of future tooth discoloration. Dentists meticulously clean and debride the pulp chamber and root canals to remove all necrotic tissue and blood products. Careful irrigation and the use of modern, non-staining filling materials also help reduce the likelihood of discoloration. Additionally, ensuring that the pulp chamber is thoroughly cleaned of any restorative remnants and adequately sealed before final restoration can prevent internal staining. Prompt placement of a permanent coronal restoration after the root canal is also advised to prevent re-contamination and further discoloration.
If discoloration has already occurred, several remedial options are available to restore the tooth’s natural appearance. Internal bleaching, often referred to as the “walking bleach” technique, is a common and effective method. This involves placing a bleaching agent, typically a hydrogen peroxide or carbamide peroxide solution, inside the pulp chamber of the discolored tooth for several days, often requiring multiple applications until the desired shade is achieved. This technique is successful because it targets the intrinsic stains directly.
For more severe or resistant discoloration, or when internal bleaching is not suitable, restorative options can be considered. Dental veneers, which are thin, custom-made shells of porcelain or composite resin, can be bonded to the front surface of the discolored tooth to mask the staining and improve its shape and alignment. Crowns, which completely cover the entire tooth, offer a comprehensive solution for both esthetics and structural integrity, particularly if the tooth is significantly weakened. Dental bonding, using tooth-colored composite resin, can also be applied directly to the tooth to camouflage discoloration, offering a more conservative and less costly alternative.