Root canal treatment is one of modern dentistry’s most effective ways to prevent damaged or diseased teeth from being lost—it’s so effective, in fact, that this procedure is performed about 15 million times a year in the United States alone. But sometimes, months or years after a root canal, a treated tooth may become stained or discolored. Is there any way to restore that tooth to its natural brightness?
In many cases, the answer is yes: It can be done with a whitening method called internal (or non-vital) bleaching. To understand how that works, let’s look a little closer at different methods of tooth whitening, and see how root canal treatment affects the tooth’s ability to be whitened.
In most cases of tooth staining—for example, when it is caused by smoking, drinking coffee or red wine, or aging in general—the color change occurs on the outer surfaces of the teeth. This type of discoloration is called extrinsic staining. It can often be moderated by lifestyle changes (need one more reason to stop smoking?), the use of whitening toothpastes, and regular in-office professional cleanings. When that isn’t enough, special bleaching products can be used to lighten the teeth. Whether treatments are given in the dental office or applied at home, these products offer the best (and safest) results when used under a dentist’s supervision.
Some stains, however, don’t arise from surface discolorations, but instead come from deep inside the tooth. These are called intrinsic stains, and they sometimes occur after root canal treatment. There are two major reasons this may happen. In some cases, when the tooth has lost its vitality due to trauma, it may bleed internally and gradually become darker due to pigments in the blood. In other cases, the treatment process itself can eventually cause discoloration. In root canal treatment (which may be needed to save the tooth), the living, infected pulp tissue deep inside the tooth must be carefully cleaned out; the tooth is then disinfected and sealed up. Sometimes, the cements used to seal the root canal treatment can cause the tooth’s structure to darken over time.
The good news is that it’s possible in many cases to alleviate the staining with whitening agents that work from the inside out. This process is called internal or non-vital bleaching, and it may be performed at the same time as a root canal, or afterward. Here’s how it works:
If the tooth is being treated at a later time, it will first need a complete examination (including X-rays) to assess its condition and determine whether this kind of treatment is appropriate. Next, after the area is numbed, a tiny hole will be made on the tooth’s back side. This provides access to the pulp chamber, a tiny cavern-like space at the center of the tooth. The pulp chamber will be cleared of debris and discolored material if necessary, and sealed where needed to prevent any bleach from leaking. Next, the bleaching agent itself is delivered to the pulp chamber, and the access hole is closed. This treatment may be repeated if necessary.
In some situations, the bleaching agent may be placed into the cleared pulp chamber during the initial root canal treatment—especially if the tooth is already noticeably stained. In all other respects, the procedure is the same.
Internal bleaching is a relatively conservative way to brighten up a tooth with intrinsic staining. While the technique is effective in many cases, it may not work in every situation. Other options for restoring intrinsically stained teeth include dental veneers and crowns—but these require more extensive (and non-reversible) dental work, and are often more costly treatments. What’s the best way to find out whether internal bleaching might work for you? Ask your dentist: he or she can assess your individual circumstances and present the options that will work best.