Do Dental Crowns After Root Canal Treatment Cause Cavities?

Q: Do Dental Crowns After Root Canal Treatment Cause Cavities?

Hello： There is a cavity in the lower right molar. <br>After root canal treatment, a crown was placed, but a few years later, the adjacent teeth and the crown also developed cavities. <br>Generally speaking, cavities are caused by the accumulation of dental plaque, which graduall

Will a crown after root canal treatment cause cavities in the adjacent teeth?

Hello, Doctor.
In 2008, I underwent root canal treatment for a cavity in my lower right premolar and had a crown placed.
Five years later, I discovered that both adjacent teeth and the crown had cavities on the contact surfaces, which were difficult to detect.
Now, my canine and premolar need treatment, and the doctor recommends placing crowns again.
However, I am quite skeptical about the cause of these two cavities since I regularly use dental floss, visit the dentist, and brush my teeth after meals.
Could it be that having crowns has made the adjacent teeth more susceptible to problems?
Another solution proposed is to excavate the cavity in the canine, leaving some of the decayed tooth structure, filling it, and encasing the remaining decay to prevent external nutrients from causing further deterioration, thus avoiding deep excavation that could damage the nerve and necessitate root canal treatment and a crown.
However, does this approach (retaining some decay) carry any risks? I would appreciate your assistance with these two questions.
Thank you.

Chris, 30~39 year old female. Ask Date: 2012/10/08

Dr. Zeng Guanghui reply Dentistry

Hello: There is a cavity in the lower right molar.
After root canal treatment, a crown was placed, but a few years later, the adjacent teeth and the crown also developed cavities.
Generally speaking, cavities are caused by the accumulation of dental plaque, which gradually erodes the tooth structure.
If the cavity is extensive and affects the dental pulp, a root canal treatment should be performed before placing a crown.
If the cavity is not too large, the decayed tooth structure can be removed, and the cavity can be filled with restorative material.

Reply Date: 2012/10/08

More Info

Dental crowns are often used after root canal treatment to restore the function and aesthetics of a tooth that has been compromised due to decay or trauma. However, it is important to understand that while crowns can protect the tooth, they do not inherently prevent cavities from forming on the adjacent teeth or even on the tooth itself if the crown is not properly fitted or if there are issues with oral hygiene.

In your case, it appears that you have experienced cavities on the teeth adjacent to the crown. This situation can arise for several reasons:
1. Marginal Integrity: If the crown does not fit perfectly against the tooth structure, there can be gaps that allow bacteria to enter and cause decay. This is particularly true at the margins where the crown meets the natural tooth. If the crown is not properly sealed, it can create a microenvironment conducive to decay.

2. Oral Hygiene: While you mentioned that you maintain a good oral hygiene routine, it is crucial to ensure that you are effectively cleaning around the crown and the adjacent teeth. Sometimes, the presence of a crown can make it more challenging to clean effectively, especially if the crown is bulky or if there are tight contacts with neighboring teeth.

3. Dietary Factors: Frequent consumption of sugary or acidic foods can contribute to the development of cavities, even with good oral hygiene practices. The bacteria in the mouth thrive on sugars, producing acids that can erode tooth enamel.

4. Underlying Issues: If the tooth that received the root canal treatment was already compromised, it may have had a higher susceptibility to decay, which could extend to adjacent teeth.

Regarding your question about leaving some decay in the canine tooth and covering it, this approach carries risks. While it may seem like a less invasive option, retaining decayed tissue can lead to further complications. Bacteria can continue to thrive in the decayed area, potentially leading to more extensive decay or even infection that could necessitate root canal treatment in the future.
The best practice is to remove all decayed tissue to prevent further issues. If the decay is extensive and close to the nerve, your dentist may consider options such as pulp capping or root canal treatment, depending on the situation.
In summary, dental crowns do not cause cavities, but they can contribute to conditions that may lead to decay if not properly managed. It is essential to maintain excellent oral hygiene, ensure proper fit and sealing of crowns, and regularly visit your dentist for check-ups. If you have concerns about the integrity of your crown or the health of your adjacent teeth, it is advisable to consult your dentist for a thorough examination and appropriate treatment options.

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