Question:
I needed to have two crowns -- on teeth 30 and 31 -- replaced. My
dentist removed the old crowns, took the impressions, etc., and put in
two temporary metal crowns. The temporary crowns touched on the top so
closely that I could not floss.
When I returned a month later to have the permanent crowns placed, my
dentist told me that there was a problem: tooth 31 had moved. It is now
about a millimeter (I think) behind tooth 30.
My dentist decided to place the permanent crown on tooth 30, put a new
temporary crown on tooth 31, and wait to see if the latter tooth moved
back to its original place. If the tooth does not move in the next few
weeks, he wants to put the original permanent crown on tooth 31, take a
"pick-up impression," remove the permanent crown, and have the dental
lab add "metal contact" to the crown. Then the modified permanent crown
will be placed on tooth 31.
Does all this make sense? Why would my tooth have moved? What are the
chances that the tooth will return to its original place? Can moving
damage a tooth? Is it standard practice to add "metal contact" to a
crown? Will the contact affect the longevity of the crown?
Answer:
My guess is that the tooth has not moved. My guess is it is a lab
error, caused by a poor die alignment. I do not think that a tooth can
move "away" from an adjoining tooth so easily. It can clearly move
towards the adjacent tooth as happens when a temporary comes off and
stays off for a couple of weeks.
I would guess that it involves adding porcelain, which is a very quick
and easy job. Adding metal would destroy the porcelain. The contact
area is most often made out of porcelain.
I get three weeks minimum to do work in my lab. The dentists I work with
build very good transitional crowns so we have very few problems with teeth
moving. In some cases we have patients in transitionals for months for the
very reasons you state.
The dentists that I have met that want work back in a week or so usually
will settle for permanent crowns that match there "temps" and should have no
problem finding a lab that will fit the bill as many times as it takes to
fill the bill.
Transitional crowns that are so tight that they can't be flossed can and
will move teeth when there is nothing distal of the prepared tooth to stop
them. This happens and is not necessarily a reflection on the quality of the
dental work you are receiving. The lab however sees this as an isolated
incidence or a trend and are about the only folks that really could make the
call on the dentist abilities in this situation and for financial self
interest would not do so.
Does this include 1st bi to 1st bi with
a high smile line? On incisors do you
impress on first visit? How about
multiple crowns in the posterior area?
If so how much time do you allow for preps,
core build ups, tissue management,
impressions, bite, face bow registration,
shade selection,shade mapping, and
provisionals
