Shade verification of anterior Porcelain Crowns- dental office part.
要看本篇的中文版，請按 這裡 （但內容有一些不同哦！）
Tof mentioned about the shade verification procedure and how it works in previous articles. Now let’s see how it is practiced clinically.
First of all, let’s see who needs a system like this.
Since this system is designed to avoid the troubles that a patient has to come back and forth for a shade mis-matched crown. (Remakes due to shade also sometimes caused the loss of faith of the patients on the dentist, tof has heard a true story in the clinic I used to worked for. A patient lost her patience on the never-ending process of changing shades. She took the crown out of her mouth, threw it on the floor and yelled: “I am done with this nonsense!” And then she turned around and stormed out of the clinic.)
Let’s say you are running a dental clinic, which aims on aesthetic dentistry and your patients are either rich or powerful (celebrities from Hollywood). Imagine the pressure you have before the date of trying in a single anterior porcelain crown. Then you will understand why you need a system like this. On the contrary, if your patients consist of mainly old folks from the countryside, simple A3 or A3.5 shade will be good enough for them, then this shade verification may not be for you.
Okay, let’s take a look at a case of a very important patient, Winnie.
Winnie just had her orthodontic treatment done (tof doesn’t do this. That’s an orthodontist’s job.). A crown was needed on #12 (right maxillary lateral incisor), and tof followed the procedure to make an impression for a porcelain crown. Then the technician sent a sophisticated 3M Lava all-ceramic crown back. Tof’s preference is, a few days before tryin for the patient, I want to make sure that the shade is right. (Do you think the rich and famous have time for multiple tryins?)
The first step is to place the porcelain crown on the SVC (shade verification cast):
A verification picture is taken by using the spectrophotometer:
This verification picture is what we use to validate the shade. Usually tof takes three of them for every single tooth in case I need further information. The following is how the Shadepilot program works for shade verification:
With a verification like this, tof confirmed that the ΔE is approximately 1.55 between this porcelain crown and the corresponding tooth on the opposite side. Let’s see what a tooth with a 2.3 difference looks like:
It looks OK, doesn’t it? The best is, tof knows about this before my patient come in for tryin.
Here is another example. This time it was Miss Chung and she needed a crown on #11:
The technician sent the crown back for the first time and tof placed it on SVC:
This was the result of shade verification:
The total ΔE was 5.64, a bit too high though. But we still know that’s because of the B in LAB (greater B for more yellowness). The natural tooth was 5.23 greater than this crown (yellower). That indicated the crown has to be yellower. Of course we can go with LCH system that everybody is familiar with (L: lightness or value, C: chroma, and H: hue). The difference in chroma is the largest in the following picture.
Of course it’s a no-go for this porcelain crown. It had to be remade before the patient comes in. This time, tof asked my technician to do a shade verification procedure before sending crowns back.
Now let’s see the ΔE of the crown sent back after rework and shade verification:
Isn’t it much better now? What does ΔE=1.9 look like clinically?
A verified crown like this gives much better assurance for the dentists. If we want to be pickier, just look at the data. #11’s value is still lower than that of #21 (1.8 of difference in L), which means it’s darker. With the SVC and spectrophotometer, the technician now knows how high the value has to be increased and make modifications accordingly. Isn’t that much more accurate?