Many past students have agreed that accomplishing a successful restoration on the typodont is more difficult than it would seem. Some have said that working on a real patient is easier than working on their typodont.
I realize that the typodont in the picture above isn’t what you or I use when we learn these skills but the point is the same. Here at dentaltutor4me, we specialize in teaching you what you need to know to pass your boards and working on your typodont is the key.
What are some mistakes that the EFDA student can avoid? Three weeks ago I made several points that I will mention again with bullets below.
- We may not condense properly over the marginal ridge next to the band. This causes the marginal ridge to break or flake apart when we carve the ridge or floss.
I was working with a student recently and as I sat to evaluate the amalgam restoration that she had just finished, I picked up the floss and as I flossed the interproximal area to evaluate the contact, I discovered immediately that the marginal ridge was flaking apart. We see this often and it is usually a problem with our condensing.
Sometimes a student doesn’t quite get the amalgam condensed thoroughly enough. Pressure is the key here. 8 – 10 pounds of pressure is more than you might think. The nib of the condenser must thoroughly make one more walk around all surfaces including just inside the band at the marginal ridge. Be sure to use overlapping strokes with enough pressure while facing all inclined planes.
Your surface amalgam should be very “soupy” because it is mercury rich. This is the weak amalgam that if not carved away, will invite corrosion later. Condense well…
- We may condense too long. There is a short window of opportunity and if we continue to condense after the amalgam has begun to set, we are weakening the final set.
Not only do we need to use enough pressure, but we also need to check our timing. There is a point at which the amalgam is setting up and if we condense longer than that time limit, we could microscopically break the structure underneath and we may not realize it until we floss.
- We may check occlusion too firmly the first time. This is an easy fix.
Just like condensing too long, checking occlusion too firmly may break the structure of the amalgam. Be gentle at first and get more and more firm each time you check. How many times do you check? You check until you see no more marks for centric or excursion. Remember, to check very firmly that last time with even pressure under your mandibular arch.
I’ve had many students over the years say that, “everything was fine until I flossed.” If that is the case, something else happened prior to flossing. Watch your steps closely to catch what might be happening.
- We may floss too early. This can shave a microscopic amount away from an already light contact. Be careful.
If your contact appears light, don’t floss at all. Let’s say that there are 36 steps to completing an amalgam from start to finish. As we improve our skill, we will get these steps done a little faster each time and if we floss too early in the process, we can cause the contact to be even lighter. There might be just enough there when the board examiner flosses, to get a snap so leave it be.
If the contact looks tight, however, floss at the very end of the procedure to be sure you can get floss through. If you cannot get the floss through, re-wedge carefully and try again.
One of the instructional videos I am working on right now deals with the issue of flossing. When and how to floss the interproximal area. In my opinion, this is very technique sensitive.
- We may take the band off too early. This may cause the marginal ridge to break.
- We may wiggle the Tofflemire too much as we loosen the band, breaking the marginal ridge.
The last two points that I made in a post 3 weeks ago are closely related and don’t need much explanation. I deal with this in some of my videos as well. Wiggling the Tofflemire or trying to separate the band from the Tofflemire and accidentally slipping in the process can break a marginal ridge. Also, holding the band too firmly with your finger can break a ridge. You will want to be extra careful during the initial set phase.
Watch your timing. Know your product. 3.5 minutes is usually safe for condensing slow set amalgam unless there is humidity. (this is for one spill) If you plan to mix another spill, your timing on this will need to be well thought out. Do so quickly. (at about 2 minutes, mix another spill and condense within about 5 minutes total.) More on this in the member’s area….
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