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Impression errors are especially important to avoid when
dealing with multiple-unit impressions because any mistakes
will be multiplied across the entire length of the bridge.
Figure 13: I thought we had seen it all when it comes to impressions, but
this may be a first. It’s a 3-unit bridge impression on the lower, but the dentist
took what looks like a half-arch impression with a full-arch tray. There
is also some material placed on the other side of the tray to impress two
molars and a bicuspid. Was this done purposely?
Figure 14: Apparently, this was done intentionally. Even on the opposing
model the doctor put a large amount of impression material on the side
opposing the bridge — impressive! He then put some material on the other
side to impress four additional teeth. How much money did the dentist
save by not impressing that lateral and cuspid? Twelve cents? Pouring
these impressions is going be a challenge and make excursions tougher
to accurately replicate.
Conclusion
Using a double-arch tray looks so easy and seems so
tempting when taking an impression on just one side of the
mouth, but it very rarely makes for an accurate multiple-unit
impression. Impression errors are especially important to
avoid when dealing with multiple-unit impressions because
any mistakes will be multiplied across the entire length of
the bridge. Even if the bridge still fits the patient’s teeth,
the bite will likely be off, which does not make for a happy
patient. For any bridge case like this, you, the lab and your
patient will be better served if you use a full-arch lower
impression tray and a full-arch upper impression tray, as
well as a bite registration between the opposing teeth and
the preps. CM
How to Watch
To view past and current
episodes visit
www.chairsidelive.com.
Also available on iTunes and YouTube.
For clinical technique tips on taking a bridge impression, watch “Chairside Live
Episode 36: The Do’s and Don’ts of Taking an Impression for a Bridge.”
42 www.chairsidemagazine.com