implants international magazine of oral implantology

I research Figs. 1a & b_Impression coping can impinge on bone. _Introduction More than 40 years of experience have shown os- seointegrated implants to be a highly predictable treatment modality, with unsuitable implant designs having been recognised and abandoned and risk fac- tors for failure identified. Nevertheless, the author feels that in spite of having restored a significant numberofimplant-supportedcrowns,problemsarise that are unexpected and not well recognised, often requiring considerable effort in arriving at a diagno- sis and a solution. Below are a series of case reports presentingproblemsthattheauthorhasencountered over the years, among either his own patients or pa- tients referred by general dental practitioners who encountered such problems and were not able to solve them. _Varying diameter of healing abutment and impression coping Whenthisoccursandtheimpressioncopingisnar- rower than the healing abutment, there is no problem, but if the impression coping is wider than the healing abutment,bonemaypreventtheseatingoftheimpres- sioncoping,andwhilstclinicallytheimpressioncoping mayfeelright,itisnotandthesubsequentcrown/abut- mentwillloosen(Fig.1). Theauthorrecommendsthataradiographalwaysbe taken to ensure that the impression coping is seated correctly.Theradiographshouldbetakenusingthebi- secting technique, since if the beam does not pass through the join between the impression coping and theimplant,thecopingmayappeartobeseatedwhen infactthismaynotbethecase. _Direct-to-fixture crowns Direct-to-fixture crowns are a good way of restor- ing implants if the fixture is in an ideal position. How- ever,incases,especiallyinthemolarregionandforsin- gleunits,inwhichthecrown—fixtureratioistoogreat, the forces acting on the crown can lead to screw loos- ening.Insuchcases,itwouldbemoreprudenttousean Restorationofimplant supportedcrowns Uncommon problems and their solutions Author_Dr Igor Cernavin, Australia 16 I implants2_2012 Fig. 1a Fig. 1b [PICTURE: ©LEEDSN]