These materials are used to help you distinguish between affected and infected dentin. Affected dentin is not infused with bacteria, and even though it might be softer than what we usually consider to be good, sound, hard dentin, should not be removed, while infected dentin must be removed before restoring the cavity. The dye evidently works by bonding to denatured collagen in the dentin, which is a byproduct of the carious process. They also help identify cracks and the location of even partially calcified pulpal tissue as an aid in canal identification for endodontic treatment.
Do They Work?
Is this concept of staining cavities to ensure removal of all caries really necessary? The studies are equivocal. Some support the use of these products, while others have found they encourage excessive sound tooth removal. There is even a concept called the "pink haze", which is lightly stained, noncarious dentin that appears pink (if you use a red dye), but it is not to be removed. Therefore, if you choose to continue to use one of these products, you should not just remove all the stained dentin indiscriminately.
The original was formulated with red dye, but there is a trend to use other, darker colors. This is due to the fact that red dye can be confused with blood if there is an exposure or, in the case of a cervical lesion, bleeding from the tissue. Darker colors, however, can be confused for amalgam stains.
Effect on Bond Strength
We tested all of our CHOICES to see if any of them had a negative effect on bond strength, including their use in combination with a self-etch adhesive. The results are listed in the commentary for each product.
These materials should be used as early into a cavity preparation as possible, since one of their main purposes is to keep you from removing too much tooth structure. They are applied for about 10 seconds and rinsed off. Any deeply stained tooth structure should be removed, usually with slowspeed burs or spoon excavators. They should be reapplied after you remove all the stained dentin to confirm no residual caries remains in the tooth. If you are near the pulp and the dentin is still stained, you will have to make the decision to excavate the additional caries or stop and place an indirect pulp cap. This is where the "pink haze" is most critical.
Some clinicians apply one of these products at the exam visit as a way of determining which pits and fissures are carious. However, there is very little justification for this procedure, especially if the teeth have not had a thorough prophy to remove plaque and other debris from these hard-to-access areas.
CAUTION: You have to be careful or some of the dye will find its way to your clothes. If it does stain your clothes or carpet, attempt to remove it as soon as possible. These products can also stain restorations, especially those with less-than-perfect margins. Dyes can be difficult to remove in these areas. Therefore, limit their application to the tooth that you are treating.