Deeper Placed Implant Fixtures: Are Abutments Necessary?

It all depends on the relative angulations of the implants and the system that you are using. Acrylic may be necessitated if you have a flange to build up. If so it needs to be removable. I personally would not have acrylic bolted into my mouth permanently. I am assuming you are using a hex system? I would give serious consideration to modifying the treatment plan to use a combination of stock abutments where possible and cad cam milled abutments where angulation cant be altered. Then a cement retained metal ceramic prosthesis if it is fixed. If you are doing a removable, then use screw-base abutments (all the systems do them, they allow 30º divergence in general) and take another abutment level imp for a cad cam bar framework. Then denture over the top. In my opinion, you may as well do the fixed as the lab fees end up roughly similar in both cases. some systems (ankylos) allow a much simplified way of doing these cases using conical and then gold abutments and a normal chrome framework. I personally don't trust normal attachments such as locators or ball etc in the upper for long term use. In conclusion. if you are fixing the prosth, abutments (milled stock and CAD CAM) and cement retained metal ceramic. If removable then acrylic is ok and there are as many ways of doing this as choices of hot dinner. Hope this helps, all the best, Mike

I would suggest flap the tissue thin it out and suture back in place with vertical mattress sutures this will give you a uniform tissue thickness of 2mm and make it easier to restore and also not compromise the esthetics as thicker tissue may.

Question for Mike Ainsworth. I am working on a maxillary implant denture case. I like the telescopic retention approach as well. You mentioned "a normal chrome framework". Could you please describe the frame design. I like the fixed comments as well. Thanks for sharing,Rick

Hi Rick, Hhe problem with chrome as you know is we cant make it accurate enough to do telescopic work without special techniques (welding etc). The key is to use a tertiary component which fits very accurately to the abutment and is cemented into a light cage in the frame in the mouth. You can do a normal chrome frame if you use syncone by ankylos. these abutments are a 5º conical type. The retention is gained by a gold coping with exactly the same 5º taper, and the prosthesis becomes similar to a fixed because the tolerences are so tight. No cement or special components, just surface tension keeps them in. The retention is incredible. The clever bit is the design of the copings which allow a rubber dam to be placed to stop undercuts in the mouth. If you do not have a ankylos implant you can buy an abutment, and I think you can scan it into the atlantis abutment software, and copy it though I'm not sure. Then use the stock gold telescopes and design your frame around them. If you cant do this then I'm sure you can design something very similar and then make galvano copings for the intermediary, which will work identically. The frame itself can be of any design, a horseshoe with very minimal metal flanges is the way i tend to do it, and I design 3 points for application of a bridge removal kit into the frame, because the patients need it to get the thing out! You can do a Hybrid frame design because it is effectively a fixed removable. The Most important aspect is that the telescopes need to be bonded in the mouth not on the model. I have pictures if you want to see one. All the best, Mike

oh yes, and listen to Dr Kurtzman. I missed the 6mm bit, Its dead easy to thin the tissue out. I also kind of missed the point of the original question, DOH!. The decision to go for abutments or not little or nothing to do with the tissue and everything to do with the relative angulations of the implants. Unless they are all verifiably parallel (done with guided surgery), you are best off using an abutment approach. Hope this helps, Mike

IMHO, Mike Ainsworth is a very smart man! When properly fabricated and fit, these telescoping prosthetic's are hard to beat. It is necessary to have at minimum three (better four or more) implants in the corners of the arch because of the stress that is transferred directly to the them (you get only a little help from the tissue borne prosthetic base.) Advantages: No elastomers to replace, great longevity and retention, patient's love them, easily corrects off axis implants (of a reasonable degree), very economical in comparison to the milled/precision alternatives, usually allows for salvaging the prosthesis in the event that an implant is lost down the road, and etc. A balanced occlusion is very important. There are no elastomers to buffer occlusal problems (just as with a fixed implant borne prosthesis.) I would think that this would be very acceptable treatment approach to the six implant case described in the initial question (along with the tissue thinning.) Best of luck! Dr. No

One could take a fixture level impression and have fabricated a cementable FPD. Cutting back the soft tissue is an option. This has worked nicely for me on several occasions.

Hello Dr. B, if you decide that the best option for your patient is an screw retained prostheses my advice is not to use an intermediate abutment, the framework can be designed for that. Why? The less conections, the best. Remember that in each joint you will have a microscopic gap wich are going to be colonized by bacteria, better if you have just one conection than two. You have to ask that the framework in the subgingival portions must be polished as mirror.