Passive Fit

One of the most challenging areas in implant dentistry is to achieve passive insertion of a screw-retained metal framework for a bar-retained overdenture or a fixed partial denture.

This frequently involves sectioning the initial framework, connecting
the segments with acrylic and picking up the united framework in an
impression to return to the lab for soldering or welding.
We invite
subscribers to share their clinical tips and pearls on this issue. We
invite dental laboratory technicians as well. Does anybody have a
tried-and-true technique that they would like to share?

9 Comments on Passive Fit

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Anon
9/13/2005
With regrads to the passivity of metal frameworks, it is true that the traditional wax and cast bars somtimes do need some altering to acieve intial fit. CAD/CAM technology can eliminate this situation. The bars are milled from a solid block of titanium. This give the bars a very light weight, no porosity, and a truly passive fit in all cases I have been a part of. This technology is available through you lab so inquire with them to get their opinion.
Anon
9/15/2005
Can the milled titanium bar metal framework be adapted to implants that are not parallel?
Anton (Tony) J. Voitik
9/16/2005
Re: Direct assembly framework for osteointegrated implants 1) I agree that the ankylosed nature of integrated implants does not allow for fit discrepancies of screw- retained restorations. 2) Laboratory records, such as implant analogs in casts (models) of the patient situation – even after a veryfication jig has been used - most often inaccurately represent the situation of the mouth when measured in the micron range. 3) To deal with this issue I developed a passive fit, solder-free method for completion of implant frameworks that has been around since the early 1990’s that assures a passive fit while minimizing the chair-side and laboratory time required to complete an implant case. It has become known as the KAL-Technique or DV Framework* and is amply described in the literature. See references below. 4) My method objectives were: a)To complete implant supported prostheses with fewer appointments and to achieve an absolutely passive framework fit - without indexing and/or framework try-in appointments. b)To guarantee that an implant supported framework will always fit passively within an accuracy range of 2.5 micron or less - regardless of number of implants and their positions in the jaw. c)To achieve these results without exposing frameworks to soldering or laser welding, to save significant chair time, and to significantly reduce the potential for dissimilar metal reactions between implants and restoration. * Design Voitik Frameworks 1) US Patent 5,106,300 2) Direct assembly framework for osseointegrated implant prostheses. Trends Tech Contemp Dent Lab. 1990 Dec; 7(10):23-31. PMID: 2203129; UI: 90364329 3) The Kulzer abutment luting (KAL) technique. A direct assembly framework method for osseointegrated implant prostheses. Implant Soc. 1991;2(1):11-14. PMID: 1883893; UI: 91355313
Anton (Tony) J. Voitik
9/16/2005
Yes, milled Titanium and Gold frameworks can be fitted to divergent implant situations.
Mark Adams, DDS, MS
9/19/2005
CAD/CAM technology is definetly the future. However, excellent clinical results can still be obtained with traditional casting methods by fabricating a 'verification' jig and relating that prior to fabrication of the metalwork. In effect, you blueprint the mastercast to insure accuracy of the mastercast. This allows you to avoid the time consuming process of cutting metalwork, re-relating it and then picking it up in an impression. From Jan '05 to Sept '05 I have fabricated ten full maxillary or mandibular castings and have another six under treatment and haven't had to cut a bar yet, verified both clinically and radiographically. I would be happy to share photographs with anyone who is interested, just contact me via email.
Jeffrey Hoos DMD
9/22/2005
I have a frame with the Kal method on Anchor press fit implant done 14 years ago and it still perfect. It was bonded together with self cure in the mouth and used Hader bars for retention. I would love to be able to do that method again. Thanks for posting. Mark would love to see photos. Jeffrey Hoos DMD
Chia-MingLee
9/27/2005
Anyone out there using EDM or spark erosion routinely for your cases? I know there is a lab in New Jersey area (Rennar Sillard and son) and UC San Fran/VA lab that does that. I like the technology but not sure how many clinicians use it besides institutional facilities. Any reply to my email would be appreciated as well. LCM
alvaro ordones
9/30/2005
The way to go when implants are not paralel is to make an open tray impression, and we can send you a sequence of a nice and simple technique. Then you ask the lab tech to make custom abutments or standard abutments that will be paralel between each other, then you can make your frame or bar to fit on the modified abutments you had made!
Anon
11/19/2005
I think You will obtain real passive fit with galvanoformed telescops on ceramic abutments and a tertiar structure (frame work)that is cemented on the galvano caps in the practice directly in the patient mouth.

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