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Conical Implant System Designs: How To Insure that Prosthesis is Properly Oriented to the Abutment?

Last Updated: Mar 01, 2010

Joe asks:

My office is restoring a case using a new implant system, and I need some feedback. As the Implant treatment coordinator, I am curious about what other offices/restorative dentists are experiencing using the “conical” – a.k.a. – “Cone-in-cone” connection design. In this design, the abutment is conical and does not have any flat surface or notches to index the position of a crown or overcastting. In other words, the form of the abutment is a smooth surface cone.

Does anyone experience a noticeable difference in the height of the final abutment post/margin when seating the final crown, as compared to the height of the impression coping when the model was poured? Does using this type of connection increase the chance that the final lab designed abutment will be too tall and may require extra adjustments , since there is no flat plane for the components to mate to? How do I know that the connection will be in the exact same place vertically? If there is a difference, do the majority of you just adjust the occlusal surface of the crown if it’s too tall? How much adjustment is normal to have to make?

Any feedback I can get will be very appreciated.

3 Comments on Conical Implant System Designs: How To Insure that Prosthesis is Properly Oriented to the Abutment?

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Carlos Boudet, DDS

11/2/2010

I, don't use that system, but you are probably referring to the Bicon implant connection which has no indexing feature. They overcome some of those problems by fabricating the abutment and the crown, and then cementing the crown on the abutment in the laboratory(extraorally), adjusting the occlusion on the model and then tapping the abutment-crown complex onto the implant in the mouth. This also overcomes the problem of a deep cementable margin.

Richard Hughes DDS, FAAID

11/3/2010

Simple, Have your lab fabricate an accurate jig and use it.

Dr. Ares

11/5/2010

In this kind of system using a precise jig is helpful and necessary. Some cone morse systems (like the Brazilian Neodent system) have a fixation screw to fix the conical abutment in place, but I find it is quite difficult to do so without having the abutment rotate. In the Neodent system, for example, there is a healing abutment with an emergence profile that matches exactly the final abutment's connection shape, so if the system you are using has a healing abutment that matches the gingival emergence profile, vertical positioning should not be an issue. The problem as I see it, is not be the seating of the abutment, but the 360 degrees of possible rotation. The cone morse taper system is a little more time consuming fro the prosthodontist, but the esthetic results are well worth the effort. I found that marking a directional groove on the abutment's vestibular side and using a hard acrylic like Duralay to make a positioning jig helps. Many times though, you still need to make adjustments intraorally. Hope it helps

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