implants - internationalmagazine of oral implantology

I case study _ computer-guided implantology Fig. 2_Surgery planning for the STL case. Fig. 3a_Surgery planning for the stone case. Fig. 3b_Surgery planning for the stone case. –an externally threaded sleeve (“osteotomy sleeve”), whichhastobeinsertedintotheembeddedsleeveand servesasaregularsleevefortheosteotomydrills(be- causeitisinternallysmooth;Fig.1c); –amodifiedextenderfordrills(Fig.1d); –an externally threaded sleeve, longer than the os- teotomy sleeve, that acts as a “bottle-neck” and is screwedintoit(Fig.1e);and –the “bottle-plug”, which is screwed onto the bottle- neck(Figs.1f–h). Fortheosteotomy,Iusedaregularsurgicalkit,nota dedicated one to precision, just modifying a plain ex- tender to fit any osteotomy surgical kits (general and notguidedsurgicalkits).Theextendershouldmatchup with the sleeve before the drill touches the bone. The prototype was realised with no endo-stop features in theextender;onlylinesindicatedepth. The bottom end of the bottle-plug is provided with ahelicalgear(tomatchupwiththecorrespondingem- bedded sleeve’s helical gear; Fig. 1i). The bottle-plug in the prototype device consists of two components, the cylindrical screwed part and the lid, and they are fas- tenedtogetherwithajoint.Thelidisintegratedintothe implant mounting component; thus, while the bottle- plugisbeingscrewedontotheneck,theimplantmount is entering inside the bottle-neck, forcing the implant downwards. The implant mount has a hollow to allow foranimplantfasteningscrew(thesameasusedtofix implantsandabutments,justlonger,toallowformini- mal screwdriver length, when it is necessary to unfas- ten the components at the end). The mount also has a gaugeforawrenchatitstop(butitcanworkforahand- piecedriveraswell).Onceimplantplacementhasbeen carriedout,themountcanbeunscrewedfromtheim- plantandverticallyunfastenedfromthebottle-plug.At thispoint,thesurgicalguidecanberemovedeasily,with noriskofhexundercuts. Thedevicemustresisttheverticaldislodgingtorque created when screwing the implant into the bone. A screwedbottle-neckperformswellforthispurposeand thelidmustbefastenedtotheverticalpartofthebot- tle-plug.Asleevetobescrewedonthebottle-plugbot- tom can be realised. SimPlant Pro Crystal (Materialise Dental)wasusedonlytoplantheimplantposition(Figs. 2–3a & b), but instead of using a surgical guide, a STL digital cast with analogue implant holes for placing analogueswasusedinthefirstcasereported(Fig.4).A plainstonemodelwitha(presumably)correctanalogue positionwasusedforthesecondcasereported(Fig.5). In both cases, the analogues were fastened to the de- vice,screwedtoit,andthenthedevicewassecuredtoa bite-like thing (using plain relining resin for the provi- sionals)toobtainasurgicalguide(nosurgicalguidefix- ationtothebonewasconsidered;Fig.6). Noguidedtappingdrillwasused.Thisissomething that should be considered, especially in high density bone. It could imitate the implant, with accuminate threads and narrow body, to be screwed to the bottle- plug,orabottle-plugdedicatedtothetappingstep,with thetappingpartintegraltothebottle-plugitself. In both clinical cases, the device was assembled chairside to allow for minimal vertical clearance (Figs. 7a–d).Aresinforbaseplatewasthenusedtocreatejigs tocheckaccuracybetweenthemodelsandthemouth. 28 I implants4_2011 Fig. 2 Fig. 3a Fig. 3b