Question Came Up - Post #10

A student was asking about choices for bridge designs for replacing tooth #3. Of course, the best choice will depend on many things, and one can't make a blanket statement. But the retainer preparations can be chosen between PFM, 3/4 crown and full gold crown.

If the facial surfaces of the #2 and #4 retainers are both poor and should be covered, then we will certainly use a PFM on #4 and maybe a FGC on #2, if the esthetics are OK. Some people have very wide smiles and the facial surface of #2 can be seen conversationally.

If the facial surface of #4 is fine and the extension in the MB area can be minimal and the facial cusp ridge is sufficiently far from the opposing tooth, then a 3/4 crown would be a conservative choice for that - but it depends on the mesial and distal tooth structure remaining as well. If there is a prior restoration which is a MOD, whether amalgam or composite, if it is not too undercut faciolingually and if the lingual walls of the boxes will have sufficient tooth structure backing them up (lingually) so that the tooth itself is not likely to break in these areas, then a 3/4 crown with box retention can be done.

If the facial surface of #2 is nice, and the esthetics of the situation demand that the facial surface be natural color, then a 3/4 crown might be done, with the same provisos as for the previous paragraph.

Provided that the requirements for 3/4 crown restorations can be met for BOTH #4 and #2, then a FPD can be done with two 3/4 crown retainers.

Since many dentists don't feel confident about doing 3/4 crowns, and the oral situation may mitigate against them anyway, the PFM is a likely choice for #4 and, depending on the esthetics, a FGC or PFM is often done on #2. Nonetheless, for most of us dentists, we would prefer for ourselves, to have the 3/4 crown retainer preparations.

In my mouth I have a 3/4 crown on #14 that had to extend mesiobucally beyond what would be hidden behind the contour of #13, so my dentist backfilled to a more conservative margin placement with composite after the gold crown was cemented. If you know what you are doing there are many options.