Figure 1: For porcelain fused to metal you need to decide where will be the thinnest metal. Usually this is buccally under the porcelain. Take a new Komet 556 long tapered diamond, cut buccally through the porcelain at the same angles you use for a crown preparation.
It can be quite time consuming cutting old crowns off prior to remaking.
Here is Martin Amsel’s six picture captions to make it easier for you.
Figure 2: Keep checking to see when you are through the porcelain and can see the gold. Now start to cut through the gold at similar angulations using an up and down motion with the diamond burr. Keep doing one area till you see tooth underneath and then move on to the next portion.
Figure 3: If it doesn’t shift then cut through the incisal/occlusal surface and try again
Figure 4: Once through all the Buccal face take an old flat plastic or even a flat bladed screwdriver, that can be sterilised, put into the slot you have made and twist to attempt to turn up the gold from the margins
Figure 5: If it does lift you can often remove the crown gently with Premolar forceps. If this doesn’t work complete the cutting on the palatal/lingual surface and then separate the two halves
Figure 6: For all porcelain crowns and veneers use a similar diamond but keep stopping and drying the area to see where you are with your depth cut. The porcelain will look chalky when dried but the tooth won’t. Often you will need to make several vertical cuts in the crown until it all chips or drills off. Do it slowly and keep checking as it all looks the same when wet
Martin Amsel runs the Young Dentist Academy that helps newly qualified dentist with general dentistry.
For more information, visit www.youngdentistacademy.co.uk or email [email protected] or call 07590 555 844.