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We explain why shade matching materials for composite restorations is a complicated science, and what you can do about it in your practice.
The science of shade matching is complicated. If a clinician isn't careful, poor shade matching can turn a fully functioning restoration into a failure. Today, we explain why shade matching materials for composite restorations is a complicated science, and what you can do about it in your practice.
Shade matching is complicated because shades themselves are complex. Understanding Albert Munsell's concept of color as a three-dimensional phenomenon and how the dimensions interact is essential to shade matching. In Munsell's explanation, color's three dimensions are hue (color), value (brightness), and chroma (saturation).1
Moreover, per the International Journal of Periodontics and Restorative Dentistry, there is more to consider when shade matching, too. Natural teeth have different amounts of translucency. If you need to mimic a natural tooth, you need to allow for light to pass through the restoration as it does in the surrounding dentition. The fluorescence of natural teeth is vital to mimic also, as the way the restoration reflects light back to the viewer makes the tooth look alive. Finally, mimicking opalescence, or the changes between how reflected light off the restoration looks versus how transmitted light looks through the restoration gives the restoration depth.1
How clinicians' brains perceive color affects shade matching, too. When you compare 2 different shades, the colors appear more alike over time. Furthermore, eye fatigue at the receptor level can give clinicians a bias toward shades with receptors that are not tired.1
To read the full explanation of what goes into the perception of color from the International Journal of Periodontics and Restorative Dentistry, please click here.
In addition to all these scientific considerations, environmental factors also can affect shade matching. When lighting is not appropriate, or the shade guide is compromised from multiple cleanings or age, or the operatory background or the patient is wearing colors that interfere with the perception of the shade, there can be additional challenges.
Some Common Best Practices That Help You Succeed in Shade Matching
When it comes to shade matching, you can only control some of the variables. Following best practices in shade-matching techniques can help. Here are a few that could help:
#1: Keep the Tooth Hydrated When Shade Matching
When it comes to best practices, Sarah Jebreil, DDS, AAACD, says that you should shade match before you get into preparation for the restoration before the tooth desiccates too much.
"I always do shade matching before I begin because as the tooth begins to dehydrate, it becomes brighter than it will when it rehydrates," Dr Jebreil explains.
"A lot of times, people will put in cotton rolls and start taking pictures of the shade. It doesn't take very long for the tooth to dry out and the shade to change," Jeff Lineberry, DDS, FAGD, AAACD, agrees.
Another significant part of her shade matching process and keeping the tooth hydrated is managing patient's whitening timelines. Like many dentists, many of Dr Jebreil's patients want to whiten their teeth before cosmetic bonding treatments. However, she has them stop 2 to 3 days before the bonding appointment, so the tooth has time to rehydrate before she attempts to shade match.
"You want them to take a break," Dr Jebreil says of whitening treatments, adding that she tells them it is okay to resume whitening after treatment. "I always tell them that the bonding probably won't change color, depending on how big the bonding is."
Dr Lineberry also encourages his patients to do any whitening they want before he does any anterior work. He wants them to wait at least a week and up to 10 days before he will do the restoration.
"I want the color to stabilize. Also, when you are going to do any direct bonding, the oxygen in the bleach can sometimes impact the bond strength," he says, adding that clinicians can counteract the effect by using 10% ascorbic acid treated for up to 10 minutes.
#2: Have Patients Smile for the Camera
In her private practice in Newport Beach, California, Dr Jebreil likes to take many photos rather than do a color map on every case. However, to get the best possible images, Dr Jebreil uses a polar_eyes cross polarization filter from PhotoMed. Polar_eyes is a magnet that attaches to the flash on your camera and eliminates the reflections that can occur when taking photos. Dr Jebreil says when she takes the picture, polar_eyes takes out the distortions that reflected light could cause so you can see the actual shade of the patient's teeth.
"You can even put the photo in black and white to ensure that the value is similar," Dr Jebreil says about matching composite. "When a photo is in black and white, it takes out the hue so you can concentrate on whether the value matches. The photos help a lot."
Dr Lineberry uses background contrast in his photos, which helps expose the teeth's characterization so the restoration matches not only in color but also in the other natural appearances of the surrounding dentition.
“The light angles and other characterizations make a huge difference, too," Dr Lineberry says.
He says another option is eLAB. The eLAB-prime software system uses artificial intelligence (AI) and image processing systems to detect the tooth and measure the shade. The eLAB system also has an automatic analysis module for color difference evaluation. Using a standard digital camera with a ring light, a polar-eyes filter, and a white-balance grey reference card, the eLAB system makes your digital camera a shade matching system. It also produces a shade recipe individualized to the patient.
"It standardizes the exposure," Dr Lineberry says. "I have friends who use it that say it works well."
#3: Be Natural.
Lighting is essential to color perception. The Dental Academy of Continuing Education published advice in their course that recommends shade matching in natural light whenever possible. Also, clinicians should match under a second light source—that is not an operatory light—to confirm the shade.2
#4: Layer it on.
Dr Jebreil says it is also essential to have multiple shades in the composite kit. It is challenging to get a good match with a single shade. Layering composite shades and types can help you get a better match, she says. You can do many techniques to match shades in restorations, but it usually comes down to layering, Dr Jebreil says.
"If it's not matching, it has to do with the layering and the composite you are using," Dr Jebreil says. "If the tooth you are restoring has a greyish Hue and your composite is too white, you probably need an enamel shade on top to lower the value. Or if you see a crack in the tooth, you probably need opaquers to block it out. Do you have too much of a dentin layer, or even if you are layering at all? Maybe the issue is that you're not using different layers in your composite. If you're not, then that's why it's not matching."
#5: Make Your Own Shade Tabs
Shade guides are an excellent tool to help you find the right shade for your restoration. Moreover, they tend to be the most affordable when compared to instrumental systems. There are universal shade guides, but there is no governing body that determines what a true A-2 is from brand to brand. Research shows that these inconsistencies exist between brands. For example, an A-2 in one brand of composite might be a B-1 in another. Research suggests that it is best to use the shade guide that corresponds to the materials you use.3
To read the third in a series about shade matching from The Journal of Dentistry, Oral Disorders & Therapy, please click here.
Dr. Lineberry says with direct resins, he likes to take some material and cure it on the tooth. If there is a type of materials you want to work with, he says you should make shade tabs out of the materials.
"It's going to give you a more realistic color match using the material in the actual shade tab versus using the VITA shade tab," Dr. Lineberry says. "If you are using direct material when doing a Class IV restoration or where there is a significant portion of tooth missing, you can use that for your shade guide."