Screw retained crowns: directly to implant, or with an intermediary abutment?

In the early years the one piece UCLA type abutments were very popular. In cases of deep tissue depth when trying in the restoration for interproximal contacts and occlusion, it could be challenging putting the case in and our multiple times often pinching tissue, etc. That being said, since screw loosening can always be a concern, I feel having one screw to deal with instead of two is preferable from a future complication standpoint. There will be cases of angulation, etc., where two screws may be necessary.

Hi, if you are inclined to believe Branemark´s view, the micro movements that come from having multiple parts would help dissipate or break occlusal forces. If you prefer UCLA principles, a well prepared restoration does not have to rely on micro movements.... In my opinion its all about the fit of the restoration into the implant. If you placed the implant in the correct position and did the leg work your restoration should be direct. Again the future of the restoration comes from the fit and also from occlusion, so if you can get nice friction from the abutment you should do just fine, so full ceramic? or over casted? or precemented crown over sla abutment? all of this are choices to be made in relation to the individual conditions of your patient and your preferences . Having said that you might be a "one abutment one time " kind of guy and that is fine too, in that case a single unit abutment with an occlusal or palatal screw will do the trick perfectly. I do all of the above depending of the gingival biotype, cosmetic involvement and occlusal situation of the patient have a great day Alex

I always try to do a direct to implant screw restoration. I think, very simply perhaps, that less parts = less issues. Im not sure if there have been studies comparing the strengths of one piece abutment/crown vs separate abutment and crown, but I feel this is another advantage. Obviously, it depends on the placement/angulation of the implant as to whether a direct access can be achieved in the first place, but if it can, why wouldn't you?

No screws...no screw problems. I perfer Bicon which I either use IAC restoration or conventional crown which we cement outside the mouth and then tap into the implant. Just my opinion ... for what it's worth. Happy Thanksgiving to all !!!

I have been making two piece screw retained restorations for years. One of the challenges, as stated above, with a one piece screw retained crown in makiing sure the abutment interface is seated properly and adjusting the proximal contacts. When you insert a one piece restoration, as it starts to bind is it because the abutment connection isn't lining up properly or is it a proximal contact that's too tight? So you start to adjust the contacts and, when the restoration finally seats you find out you've opened up a proximal contact! Then back to the lab. I get around this issue by making a custom (atlantis) abutment then making a crown (either pfm, monolithic e.max or monolithic zirconium) with a screw hole already in it. I place the abutment separately to make sure it's seated properly, then try in the crown to adjust proximal contacts. Then i cement the crown to the abutment with any permanent cement intraorally. After the cement sets, unscrew the restoration, check to make sure the cement is removed then screw it back in again and fill the access with whatever material you like. You then have a screw retained crown, direct to the implant level. This is also much less expensive than casting up a one piece restoration since the bulk of the abutment is machined titanium which is a lot cheaper than a big slug of gold alloy cast to a machined "UCLA" cylinder. Hope this little technique helps!

George Priest, a U.S prosthodontist, has a webinar on Viva Learning which one can access, it's a superb lecture on how to deal with soft tissue profiling and preservation. I now rarely ever take an implant level impression without having profiled the soft tissue : that can vary from a wider tapered healing cap to a customized cylinder temporary. I go screw retained one piece as often as possible, have a great lab in the UK ( I live in Ireland) called Attenboroughs ,who can make an integrated abutment and crown in house for a very reasonable cost. I don't look at my wife's gold any more :)

Well, in fact, several studies in the mechanical engineering field have demonstrated that its better to have more parts.. particularly to dissipate the stress and prevent one to one force transmission from crown to bone. gumbate kudasai

If you have engineered your case correctly, you do not have to be concerned about force transmission from implant to bone. The reason Branemark liked the old gold screws was that they were cantilevering the prosthesis "to the spine". Can't tell you how many gold screws we went through in the early days until we changed our prosthesis design and, voile, no more screw breakage, no abutment loosening, and no biomechanical implant failures. The original external hex with the type of abutment they fabricated was just an extremely poor design and had horrible microleakage leading to crestal bone loss. The FEWER the design components, the lower the micromovement and microleakage resulting in far better clinical outcomes (stability and biologically). RJM