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16 I I special _ endo-implant algorithm outer edge of the implant, thus distancing inflamma- torycellinfiltrateawayfrombone.Hypothetically,less crestalbonelossisexpectedandanincreasedimplant- abutment disparity allows more stable peri-implant soft-tissue integration. Baggi et al. conducted a finite element analysis experiment to define stress distribution and magni- tude in the crestal area around three commercially availableimplants:ITIStraumann(Straumann),Nobel Biocare (Nobel Biocare) and Ankylos C/X (DENTSPLY Friadent).58 Numericalmodelsofmaxillaryandmandi- bularmolarbonesegmentsweregeneratedfromcom- puted tomography images and local stress vectors were introduced to allow for the assessment of bone overload risk. Different crestal bone geometries were also modelled. Type II bone quality was approximated and complete osseointegration was assumed. It was concluded that the Ankylos C/X implant based on its platform switched and sub-crestally positioned de- sign demonstrated better stress-based performance andlowerriskofboneoverloadthantheotherimplant systems evaluated. Platform switching with a stable implant-abut- ment connection is increasingly accepted essential implant design features required to reduce or elimi- nate early crestal bone loss. A bacteria-proof seal, a lack of micro-movement due to a long friction grip taperedchannel,andminimallyinvasivesecond-stage surgery without any major trauma for the periosteal tissues are also important factors in preventing cer- vical bone loss. A preconfigured platform-switched design has a significant impact on the implant treat- ment in aesthetic areas, as not only is the tissue biotype preserved, but it has also been shown to be enhancedbyosseousgenerationoverthecollarofthe fixture (Figs. 12a & b).59,60 Theendo-implantalgorithmparallelsthequestion: Whichcamefirst,thechickenortheeggasanexample of circular cause and consequence. It could be refor- mulated as follows: Which came first, X that cannot arise without Y, or Y that cannot arise without X? An equivalentsituationarisesinengineeringandscience knownascircularreference,inwhichtheparameteris required to calculate that parameter itself. This is the essenceoffoundationaldentistry.Ifnaturecreatesthe ideal, are we as clinicians not responsible for replicat- ing the ideal, should adverse conditions irrevocably alter nature and necessitate its elimination? Nature wisely created a structure that could har- moniously interpolate hard and soft tissue, act as the portal of nutrition and communication for the body,andbethegatekeeperonguardandinfunction throughout our lifetime. Our role is to ensure that we re-engineer nature; we must adhere to its rules, itslogicandfundamentals.Thisisnotaneasytask,as filtering out the best range of evidence from a wide range of sources, presenting clear, comprehensive analyses and incorporating patient experience is a Herculean task. In many ways, this is analogous to Alice’s Adventures in Wonderland, as so much of what we do grows curiouser and curiouser as each new innovation demands that we go through the lookingglassanddeterminewhatAlicefoundthere._ “There’s no use trying,” said Alice. “One can’t believe impossible things.” “I daresay you haven’t had much practice,”saidtheQueen.“WhenIwasyourage,Ialways diditforhalfanhouraday.Why,sometimesI’vebelieved asmanyassiximpossiblethingsbeforebreakfast.” —LewisCarroll Editorialnote:Acompletelistofreferencesisavailablefrom thepublisher. roots2_2010 Dr Kenneth Serota 4310 Sherwoodtowne Blvd. Suite 300 Mississauga,Ontario L4Z 4C4 Canada E-mail:kendo@endosolns.com Websites:www.endosolns.com | www.rxroots.com | www.ankylosworld.com _contact roots Fig. 12b Fig. 12b_The expectation of a precise cone fixture-abutment connection is that the crestal bone will overgrow the fixture platform and remain in that position regardless of whether the implant was placed in a grafted site or immediately placed in an extraction site. Die-back or saucerisation is not a consideration.