implants international magazine of oral implantology

I research serts correct any pro- cessing errors. It must not be used in a two- implant situation. Several studies have shown that conven- tional bar- and clip-retained overdentures transfer significantstresstothesupportingperi-implanttis- sues(mainlybone).9–11 ThekeytotheSFI-Barsystem is that the bar is assembled in the patient’s mouth without the use of soldering, laser welding or con- ventional bonding techniques, thus reducing stress transmission to and bone loss around the implants. Studies have demonstrated that any laboratory- based technique that requires a master cast made from a dental impression will result in a bar that is nottrulypassive.8,9 Asaresult,severalauthorshave suggested that the only way to achieve a passive fit would be to assemble the framework intra-orally and then bond the bridge pontic in place.12, 13 This is the method employed with this system. There is no casting, soldering, laser welding or bonding of components when fabricating the de- finitive bar. This, combined with the universal ball- jointnatureofthecomponents,ensuresatruepas- sive fit when the bar is assembled. The finite ele- ment analysis clearly shows the stress-free nature of the bar when being assembled and when the prosthesis experiences loading (Figs. 2a–c). No laboratory time is required to fabricate the bar and there are no costly implant components or gold-alloy charges. Clinically, there is no need for the bar sections to be soldered in an attempt to achieve passive fit—a step that may need repeat- ing—as with the conventional method. There are no soldered or laser-welded joints, so the bar assembly has no inherent weak points that mayfractureorcorrode.Thebarisassembledbythe clinician, who also attaches the E clip intra-orally. The reduced number of clinical appointments, lab- oratorytimeandcomponentcostsresultinreduced treatment costs for the patient. In the case pre- sented, for example, the bar assembly was com- pletedinonlysixminutes.Thisisapproximatelythe sametimeittakesforapolyetherimpressionmate- rial (like Impregum) to set! _Conclusion The SFI-Bar is relatively inexpensive compared withconventionalgoldcastingsandCAD/CAMop- tions. The overall cost of the prosthesis and treatment time are sig- nificantly reduced com- paredwithconventional and CAD/CAM tech- niques. Precision-milled components provide an improved quality of fit. The physical and me- chanical properties of the component materials can be controlled accurately, which is difficult to achieve with conventional casting methods. The SFI-Bar can be connected to two or more implants tocreateafull-archbarifneeded,whiletheSFI-Bar system produces a bar assembly that seats pas- sively as demonstrated by finite element analysis. The passive-fit bar assembly can result in greatly reduced stress transmission to the supporting implants. Studies have demonstrated that this is alsoaviabletreatmentoptionforimmediate-load- ing situations in the mandible, provided that the implants achieved insertion torques exceeding 50 Ncm approximately._ The finite element data and images were kindly providedbyDrLudgerKeilig,EndowedChairofOral Technologies,UniversityofBonn,Germany. Disclaimer: The SFI-Bar, implant adapters and E clips were provided by Cendres+Métaux. The au- thor did not receive any financial inducements to write this article or payment towards laboratory charges, nor was any other kind of payment given orreceived. 14 I implants2_2012 Fig. 14a Fig. 14b Dr Tussavir Tambra BDS,DDS,MS Prosthodontics (Michigan) Wolverhampton,United Kingdom dr.tambra@hotmail.co.uk _contact implants