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ePaper created 2014-10-07, 09:31:41 | version 1.30.01
I special _ 3-D planning for implants 30 I cone beam3_2014 Currently, we are making the step from plaster cast and wax-up to digital model and digital recon- struction.Thisinterestingnewapproachhastoprove its worth in the practice first. Therefore, we have to determine which of the many digital features are essential in treatment of the patient. _Main features of 3-D planning Only by the evaluation of 3-D data does a preop- erative decision on how the desired prosthetic result canbeobtainedbecomepossible.Withthefinalresult in view and mind, a solid basis for deciding upon the necessity and type of augmentation and whether re- movableorfixeddenturesareindicatedinedentulous jaws is provided. There are often bone defects, whose extent must be evaluated. They are classified accord- ing to Fallschüssel and Atwood and the classification demonstrates that, as a rule, horizontal bone loss occurs first, while vertical bone is lost gradually. Restoring horizontal bone is important for pros- thetic restoration primarily for aesthetic reasons in theanteriorareaandprimarilyforfunctionalreasons in the lateral areas concerning the position of the implant in the dental arch. These defects can be optimally corrected via surgical restoration of the original bone volume. For each case, measurements for positioning the implant (such as inclination— to be performed by the surgeon) and measurements for the prosthesis (to be done by the dental techni- cian) must be taken. The latter, for example, buccal crown overhangs or mucosal facings, prevent hy- gienic design of the superstructure and quite often result in aesthetic deficiencies. Ifrestorationofverticalbonevolumeisnecessary, forinstancewithFallschüsselClass4frontalor2lat- eral or Atwood Class 4 defects, a more costly two- step technique has to be followed in most cases. At this point, it should be noted that almost all the atrophypatternsmentionedonlyinvolvethejawand do not concern the functional components of the dental arches. Arutinov et al.3 postulate that this must be compensated for by angled implants. Kinsel et al.4 conclude that only the length of the implant is significant for implant loss. This means that as great a bone volume as possible must be used. All of the above-mentioned planning decisions can only be made soundly if information about both the 3-D anatomy and the desired prosthetic solution is available. The guidelines of the European Association of Dental Implantologists5 offer a critical discussion of angled and short implants. Angled implants require a bone quality above 3, 3-D planning and guided implantation, among others. Planning based on an impression with fabrication of a planning cast is crit- ical for the final outcome of implant placement and thus for the procedure. This will determine the re- quired treatment steps and desired treatment out- come. Quite often, this step is not accorded the necessary importance in daily practice. Adequate planning should be done by the dentist and a special appointment with the patient should be made to ob- tain consent. With two-step procedures, repeating planningafteraugmentationandasecond3-Dradio- graph may become necessary. _Digital 3-D planning Today’s prosthetic planning possibilities offer alternatives to conventional casts. Two digital pros- thetic planning tools will be discussed here, SimPlant (Materialise Dental) and SICAT/CEREC (Sirona). Both these tools are alternatives to the conventional approach described above via digital planning. With both methods, the surface of the neighbouring teeth and soft tissue is scanned and matched to the ra- diological 3-D data. This can be done from a cast (SimPlant and SICAT) or an intra-oral scan (SICAT OPTIGUIDE procedure). Then, a digital cast is created with the prosthetic planning programme. The ob- jectives of these methods are simplification and shortening of the workflow (Graphs I & II). Fig. 2_Depication of anatomical varieties in the lateral mandible (classification according to Atwood). Figs. 3a & b_Planning in the lateral mandible with setup cast in situ (SICAT) (a). Post-implantation with surgical guide for control (b). Fig. 2 Fig. 3b Fig. 3a CBE0314_29-33_Ehrl 30.09.14 14:16 Seite 2