I thought it would be fun to look back at some of the work I did during my second year here at Midwestern. After completing nearly 400 projects in the simulation clinic, my hand skills have improved tremendously.
At one time, it wouldn’t have mattered which hand I held a handpiece in. Like first learning how to write, both of my hands were equally incompetent.
Now, projects that once took me 45 minutes to an hour require just 10-15 minutes. Moreover, my finished work is significantly more polished than anything I did at the beginning.
Class II Preps
We had a lot of practice with Class I preps at the end of our first year. MO and DO Class II preps are really just a Class I prep that has been extended all the way to the interproximal area. Naturally, this made Class II preps a good starting place for us during our second year.
Things started pretty well for me this year. I think the groove extensions could have been a little bit longer, but overall not bad! The pulpal floor is smooth, the depth is consistent, the isthmus (narrowest part) appears to be about the right width, and the walls appear convergent where they should be from this perspective.
The hardest part for me with the interproximal boxes on Class II preps was avoiding adjacent tooth damage. When you are working in tenths-of-millimeters, it is very easy to slip and cut into the neighboring tooth.
We learned to drill our proximal boxes to depth while maintaining a thin layer of material between the teeth. We call this the “eggshell” technique. After you drill to the proper depth, you use a hand instrument (usually a hatchet) to break the eggshell and open the space between the two teeth.
Class II Restorations
We did a variety of amalgam and composite restorations this year. As I said before, much of what we did in the beginning revolved around Class II preps and restorations.
On the left is one of my early Class II composite restorations on a premolar. Unfortunately, I think there is an open contact there in the interproximal space. On a practical exam that would be an auto-fail. But, that’s why we practice!
The middle shows an amalgam restoration on a different premolar next to a molar with a nice DO composite restoration. I captured the occlusal anatomy pretty well with the amalgam, but the central groove is a bit off. The neighboring composite restoration looks pretty good, though possibly a bit too narrow.
The diastema there between the molar and premolar would still have counted as an auto-fail on a practical exam. I probably opted to contour the marginal ridge and interproximal space to match the rest of the tooth for this project.
We didn’t polish our amalgam, and I didn’t learn that I could burnish it to a shine until later in the year as you can see in the image on the right.
This was definitely the year of crown preps. I’m told that Midwestern’s dental clinic produces more CAD/CAM dentistry than any other clinic on Earth. We are really big on crowns here, so we clearly need to be good at crown preps.
First, let’s see some of my early crown preps. The #19 prep (left image) looks pretty good. I was trying to capture the occlusal anatomy, and my axial reduction is about right. The cusp heights are a little off though, and I clearly wiped out the distal marginal ridge, a big no-no.
The middle image is a separate attempt on the same tooth. You can see that I still hadn’t figured out proper occlusal anatomy. I was trying to replicate the cusps (primitively), but in this case I wiped out both marginal ridges. Woops!
The image on the right shows that I was prone to over-reducing my preps early on in addition to neglecting the marginal ridges. It took some time for me to figure out a reproducible method to get an exact occlusal reduction every time. Now my eyes are calibrated enough that I can approximate almost exactly how deep to cut.
My later attempts at cutting crown preps were much better. Not only were they more precise anatomically, they also took a lot less time. By the end of the year, I was cutting these preps in 10-15 minutes. (Sorry for the blurry image)
Like I said earlier, Midwestern is very big on CAD/CAM dentistry. We do a lot of same-day crowns over in the clinic. Our second year is the time to learn as much as we can about CEREC and E4D.
After the design and milling phase, crowns are stained, glazed, and baked. Squirting stain onto glass slides and then painting it on with brushes brought me back to 3rd grade arts & crafts class. Dental school is really difficult most of the time, but sometimes it can be a lot of fun too!
No SIM lab would be complete without a healthy dose of stress. There were a few projects this year that really challenged us. Composite veneers and onlay preps were two of the harder projects for me.
You can see that I tried to capture the surface anatomy on my composite veneers for #8 and #9. In another veneer project after this image was taken, I learned to add more subtle details to the labial surface. You can see that the cuts I made to the surface here reflect light unnaturally.
Once you get a feel for the instruments and learn how to alter light reflections on the surface, it gets easier to capture the look and feel of natural teeth.
The hardest thing for me was trying to match the labial surfaces by creating mamelons (developmental anatomy on the labial surface). At first I struggled to match incisal edges and embrasures (triangular spaces between teeth). Once I got those bigger concepts down pretty well, it was the small details that challenged me most.
Onlays were particularly difficult for me because of their complex interproximal relationships. The distances between teeth have to be just right and keeping all of the walls properly divergent can be tricky.
Of course we still practiced a lot of endo this year. I regret not taking more photos, but I scrounged up a few to share here from my phone. Apologies for the bad image quality…
I had some ups and downs with endo this year. I had one root fracture and a perforation of the crown near the root. But most of my endo turned out pretty good. Although I made a lot of mistakes, I learned from them.
You can see in the second image above that my gutta percha extends past the radiographic apex. There is also a bit of sealer that came out with it. Although it’s not ideal, it isn’t really a big deal either. The bigger problem is the fact that I probably missed a small canal that extended off the main one near the pulp chamber. If you maximize the image you might be able to see it.
One for the blooper reel
Below is the result of pushing System B (endo heat source) too hard into the canal of an over-dessicated natural tooth root. My biggest failure was continuing to inject more gutta percha without knowing where it was going…
Extractions, Anesthesia, and Lasers
We ended the year with dental lasers, anesthesia, and surgical extractions. We used steer mandibles, hot dogs, suture mats, and each other for practice. There’s not much to say about these procedures that I didn’t already talk about in other articles. Most of our experience here will come from the clinic.
Tomorrow is my first day in the dental clinic. I won’t actually see my first patient until Tuesday, but I will be sure to write about it here!