Abutment preparation intra-oral vs on model: What are the pros and cons?
Intra-oral implant abutment preparation and/or refinement possesses advantages in the accuracy of the preparation design and simplicity in technique. In practical clinical terms what are the advantages and disadvantages to Abutment preparation intra-oral, and what are the common indications and contraindications for this approach compared to abutment preparation on a model? Thanks
8 Comments on Abutment preparation intra-oral vs on model: What are the pros and cons?
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FJDuCoin
6/19/2012
The biggest con is the loss in production time. Why have a patient in the chair for something you can do in the lab, freeing the chair up for other production? You may want to refine the prep in the chair, but most of the prep should be done on a model. I usually just take a good full arch impression with a good material, pour up the model myself so I am confident the analog is correct (do a small pour placing the stone with a brush w/o a vibrator to lock the analog in place, let that harden and then pour up the rest of the model), and send the whole thing off to the lab and let them refine the abutment and make the crown and get the finished case back.
Mike S
6/19/2012
If adjusting intraorally, use COPIOUS water spray to avoid killing the bone around your implant. In the lab, I don't know how much heat destroys the temper of the metal, but use caution.
stephen travis
6/20/2012
Adjusting in the mouth also makes it difficult to know exactly the material dimensions. This can lead to small or thin areas of Zr which can been prone to fracture. If ti- the risk is leaving bits in the tissue and discoloring it. H.eat and sparks and very difficult to get as smooth as a machined or milled abutment
Best abutment design is with Cad-Cam systems now. Procera and Atlantis are best examples, same price as off the shelf abutments. If adjustments required I would do this on the replica out of the mouth
David Broughton. Dental T
6/21/2012
Without a doubt, have the abutment prepped and/or modified on the model in the lab.
1. Instruments and access to abutment are easier in the lab.
2. If experianced, your lab technician can more easily modify the abutment relative to the surrounding teeth and all space available in order to give a good aesthetic result. The Technician should design from the final morphology, back to the desired dimensions for the abutment. Even more important in the anterior aesthetic zone.
I would recommend using a titanium link to be screwed from abutment to fixture, and then with the use of CAD/CAM, design a Zirconia abutment, colour co-ordinated to final shading, followed by CAD/CAM designed Zr coping to be veneered with ceramic.
Best of all worlds!
I like FJ DuCoin's method of locking the lab analogue into impression before forwarding to lab, thus avoiding discrepancy!
FJDuCoin
6/21/2012
Rarely the case will come back with the analog rotated 1 or 2 degrees, not much but enough to throw the case off. At least when this happens I know it was MY fault and not the labs. This makes everyone's life easier, still need to be fixed, but I know where the problem was. (Of course you don't know this until you try it in the patient, and then, of course, I always blame in on "Bob" my lab guy! Sorry about that you lab guys out there.)
David Broughton. Dental T
6/21/2012
Addition to previous comment
Richard Hughes, DDS, FAAI
6/22/2012
It is best to save chair time and enhanced production by prepping at the bench. The patients do appreciate this consideration! One can fine tune in the mouth if necessary.
r.kamala kannan
7/19/2012
if its a single crown implant(either anterior or posterior)i would prefer to finish the abutment preparation intra-oraly.if its a full mouth or more than three abutment better to do preparation in lab.
