Grey margins: 4 mistakes to avoid
I am still seeing that grey line. My restoration is visible. What can we do when our anterior restorations keep failing aesthetically? By following a couple of simple actions, we will change the way we perform everyday dentistry. These actions are actually nothing elaborated or complicated: on the other hand, they are extremely simple, and the only thing they require is constancy.
It is very frequent to obtain gray restorations when working with composites. Each composite has different optical behavior, but, speaking in general, by increasing the thickness of composite enamel, we actually make the restoration become greyish.
We can see three glasses in which there is a glass another glass inside. In the first picture, on the left we can appreciate both glasses. However, in the third one, there is also a glass inside but there is material between them, which makes it optically disappear. This is a light effect in which the refraction and reflection indexes are equal. In a restorative material, researchers serch for this effect, for the light to travel in the same way as in a natural tooth. The refraction index tells us how the light will pass through an object and in which direction it’s gonna go. The way that the light travels in the enamel is very effective, as it is reflected and refracted a lot, but usually in composites the light travels less efficiently.
Dentists, when obtaining grey composites could decide to change for a more whiteish enamel. When adding white to an enamel it becomes more opaque. But this is not convenient because we need translucent enamel masses to be able to see the dentin color and effects beneath the enamel layer. The key factor is on enamel thickness. We must reproduce enamel composites in a smaller thickness than the natural enamel to achieve an optical integration. This is the only way to make two completely different materials look the same. The most frequent mistakes are the following 4.
MISTAKE no. 1 – USING THE VITA SHADE GUIDE AS THE ULTIMATE REFERENCE
Take your vita shade guide and then take your syringe with the same name (e.g. A2) printed onto its label. I had the opportunity to be in touch with dentists from all around the world and I frequently see that is usual to use vita shade guide to choose the color when performing direct composites. What happens if an A3 color from the vita shade guide is chosen and then you pick up an A3 syringe from the composite system you have in that moment? Is more than sure that you are committing a mistake. (1,2)
MISTAKE no. 2 – BELIEVING THAT DIFFERENT BRANDED COMPOSITES WILL LOOK THE SAME
An A3 from one brand is completely different from another brand. In this image we can see 8 syringes named A3 dentin on their labels. Different brands, same names, and completely different properties. Different hue, chromaticity and opacity. It’s impossible to have predictable results if you believe that A3 are all the same.
MISTAKE no. 3 – NOT CAREFULLY CONSIDERING THE MARGINS
Sharp margins must be finished and polished: trying to restore sharp margins just like these will most probably end up in aesthetic failure.
To hide the margin we usually use a long bevel (between 1.5mm-2mm).
Margin polishing can be done with an abrasive disc, or a rubber tip or a multi-blade bur.
MISTAKE no. 4 – NOT CALCULATING THE ENAMEL THICKNESS
Issue: some dentists don’t even know the enamel thickness they used. It is crucial to reproduce the precise enamel thickness to obtain the right color. We prepared composite discs, different enamel thicknesses, to better understand the behavior of composite. We prepared discs from different composite brands, and, in general, when using 0,3 mm enamel on dentin, the enamel effect is almost imperceptible. 0,5 mm is the right compromise because it modifies the dentin but without lowering value; 0,7 mm enamel thickness is usually too much because restorations become grey. When 0,9-1 mm thicknesses were used, the enamel hid the dentin and lowered the value.
The key factor is to control the enamel thickness (3,4,5)
We usually use instrument Misura (LM Arte kit) to measure the 0,5 mm ideal enamel thickness.
The opposite end is useful in narrow areas or near the cervical third where the “probe end” does not fit.
Class IV fracture, after radiological evaluation, color was taken with a custom shade guide (6)
Isolation and cavity preparation.
Proximal and palatal wall build-up: after having this structures, dentin can be inserted and calibrated.
A White halo was created with a tiny amount of A1 dentin.
After enamel placement.
Result after rehydration. In some situations the result is not perfect but in most of the cases the aesthetic result satisfies the doctor and patient expectations.
Class IV fracture before restoring.
I followed exactly the same protocol to hide the margin. It is important to use a personalized shadeguide to choose the color, to bevel the margin, to polish and finish the margin and control the enamel thickness.
Class IV fracture before restoring.
The same concepts are taken into consideration in each clinical case when dealing with anterior restorations.
Class IV fracture and old composites.
Exactly the same concepts are used by other doctors (this is Dr. Walter Devoto’s clinical case) with predictable results in the daily practice.
Keep in mind that:
– VITA color is not what you get in your material
– All composites have different color and opacity
– Margins should be beveled and thoroughly cleaned
– The thickness of your enamel has to be 0,5 mm, or very very close to that value
The margin error rate in anterior restorations will tremendously decrease, with no fancy equipment and no complicated techniques.