When a client of mine needed to replace an old crown for a patient, he gave me an opportunity to accentuate some of the differences between typical work and the work we do here. He sent along the sectioned crown as a shade reference, but it allows us a closer look into why we do what we do.

So what do YOU see...?

Well, some might say first of all that I’m not comparing apples & apples by comparing one of my anteriors vs mr average posterior crown. Maybe so, but most of my anterior copings are made  the same way as I make my posteriors. In other words, there is support where it is needed, and thinned where needed. The majority of my posteriors measure .3mm at their thinnest areas and anteriors 0.1mm. Why so thin? To create more room for the element that will make this crown look like a tooth. Does it take extra time to wax & trim? Yes. Do your fingers burn when adjusting these down? Sure! Those technicians reading this can relate to lost nerve endings on finger tips from trimming metal copings. That’s why most other labs don’t do it. It requires too much time & effort. Even if the increased space  for porcelain is 0.2- 0.3mm it makes a huge improvement optically. It’s worth it, and it doesn’t compromise the strength at all.

We’ve talked about the coping a bit, now let’s look at the ceramics. Looking at the porcelain in our two samples, what jumps out at me is the dimension occupied by opaque. Opaquing is necessary, but you can see the same masking of the metal is achieved in a MUCH thinner dimension in the crown on the left. Why is the Joe Average Crown thicker in opaque? This could be a result of the porcelain brand used, lack of experience or care or all of the above.

There are other things I could highlight, but the final point of note is the margin configuration difference. The crown on the left was made with the Altered Coping design (per Don Cornell). This technique is where the metal coping is actually cut back up the axial wall and shoulder porcelain replaces it. The advantages are obvious hopefully. This technique increases light transmission to this critically esthetic area of the tooth. Indeed this is the area where most battles of esthetics are lost. So Is there a strength compromise? In the 10 years I have been doing this technique, I haven’t had one failure from using this technique. Actually there is research that the strength of the crown (once cemented) is the same as that of a typical porcelain butt margin even when the coping is cut back 2mm up the axial wall! This technique has been around for years. It’s no new development. So why aren’t all the labs doing it? Again time & effort is the reason. These techniques are time and labor intensive and highly technique sensitive in addition. Few other things bring intense frustration to the face of a technician than asking them to do a direct margin lift on a die with an altered coping.

Unfortunately, what we see here is that the final outcome of the crown is highly dependent on the technicians that dont have the glamorous positions. The waxer, metal finisher and opaquer can significantly impede the process of making a great crown look good. Maybe we shouldn’t be asking how good your ceramist is, but how good are the guys who pass him (or her) the baton? A great anchor runner only benefits the team when the other members run their leg of the race well.