implants - international magazine of oral implantology

I industry report _ TRIPOD procedure Fig. 11_Second impression secured to reduced inital model mounted in the articulator. Fig. 12_Modified model: the yellow part corresponds to the initial impression; the pink part was poured at the time of surgery. Figs. 13a & b_Initial provisional bridgework on Thommen SPI® VARIOmulti temporary caps in place. occlusaladjustmentsshouldbeminimal,evenperhaps none being required. Thommen SPI®VARIOmulti tem- porary caps on are filled with temporary light-cured material to close the screw channel and the patient is advisedtotreatthetemporarybridgeworksinagentle manner. Sutures are removed after ten days. The aesthetics is re-evaluated three months after surgery, before ini- tiating the final prostheses, owing to subsequent loss of tissue volume. Additional temporary bridgework is oftenrequiredtotestthatthefinalaestheticwillbead- equate before proceeding with the definitive prosthe- ses. The final prostheses is either manufactured as a casted bridge using SPI®VARIOmulti caps or by CAD/CAM technology such as NobelProcera from No- belBiocare. _Discussion There are multiple technical benefits of the TRIPOD procedure. Precision implant placement is achievedbyremovingpositionalandmechanicalarte- facts, particularly when the actual surgical guide is screwed onto stable implants. In other words, there is no movement evoked by a bite variation or tissue dif- ferences, and if the patient moves during the CT scan, theguidemoveswiththeanatomicalstructures.How- ever, there is no way to conquer geometric, hardening ordigitalartefacts.Thereisstillroomforasmalldegree (<1mm)offreedominimplantplacementand,ifnec- essary, final correction can be done after the initial drillingwiththe2.8mmdrill.Thisresultsinamaximum freedomofapproximately0.7mmindiameterforafi- nal implant site with a diameter of 3.5 mm. However, considering that the last drill at the centre is just half of this value, this freedom corresponds radially to 0.35 mm, providing an opportunity to adapt the im- plant site preparation to anatomical conditions slightly.Thisdistanceof0.35mmissufficientlyimpor- tant to become particularly significant for leaving somebuccalbone,butitisstillsmallenoughtobehan- dledbythedentaltechnicianforidealprostheticscrew placement.Nevertheless,theinitialimplantplacement cannotexceedthislimit,whichevokesthenecessityof verypreciseinitialdrillingand,atthetime,anadditional steptoverifythatthesurgicalguideisactuallysuitable for use. Compared with flapless techniques, open flap surgerynotonlyallowsthevisualopportunityforcon- trollingbonesitepreparation,butalsoretainsprecious keratinised tissue that is important for both marginal tissue stability and volume. The patient’s reaction to thisprocedure,withitsassociatedpainanddiscomfort, stillhastobeexaminedinfuturestudies. Another benefit of this procedure is that sterility is maintainedthroughoutthesurgery,sinceallmaterials used can be sterilised, which is not the case with com- mon guides such as NobelGuide or the SAFE SurgiGu- ide®,whicharebothmadeofastereolithicresinandare currentlynotcapableofundergoingsterilisation.Inad- dition, the precision of the procedure allows the im- pressiontraytoremainunmodified—andthussterile— throughoutthesurgery. YongandMoy8 statethatimplantlosswasprobably primarily related to the absence of proper cooling abil- ity when using NobelGuide, since most of the late im- plant failures involved long implants in cases in which the guide was used directly at the gingival contact. In- 34 I implants3_2011 Fig. 11 Fig. 12 Fig. 13a Fig. 13b