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16 I I case report _ CAD/CAM Fig. 1_Subjective and objective prosthetic success criterions. implants1_2010 _Prostheticdevicescanbefittedinvariousways. Digitaltechnologieshavemadetheirmarkinimplan- tology for quite a while, and they provide options for quality solutions. Classical indications for implant- prosthetictreatmentsincludedenturesforthetooth- lessjaw.Forthistypeofdentures,clinicalstudiesdoc- umentahighsurvivalrateofabout85to90%(Attard et al. 2004a, Attard et al. 2004b) with observation periods of up to 20 years. Accordingtothenumberoftheinsertedimplants, various prosthetic concepts have established them- selvesforthefittingofsupraconstructions(Zitzmann and Marinello 2002). Generally, there is either a fixed denture mounted on six to eight implants and borne by these only, or a removable denture with a reduced number of implants. Thedecisionprocessfortheselectionofasuitable denture depends, on the one hand, on subjective cri- teria (patient’s expectations, financial conditions) and,ontheotherhand,clinicalaspects(anatomiccri- teria, technical and clinical reliability of implants and supraconstruction). Accordingly, the success of the prosthetics depends on these factors (Fig.1): _Subjective criteria (patient satisfaction and quality of life); _Objective criteria (probability of survival); and _Necessarymaintenanceeffortduringthelifetimeof the denture. _Criterions for the selection of the type of denture Fixed as well as removable implant-prosthetic dentures in the toothless jaw, as opposed to the con- ventional full denture, have proven to significantly increasethepatients’satisfactionandtoimprovethe ability to chew (Raghoebar et al. 2003, van der Bilt 2006).Thismeansthatalreadytheinsertionoftwoto four implants can lead to a clear improvement of the qualityoflife.Therefore,theremovableimplant-sup- ported and implant-retained coverdenture prosthe- sisisnowadaysconsideredaneffectivetherapy.How- ever, there was also evidence that, in particular, the choice of fitting elements (magnets, ball-heads, bridges,telescopes)inaremovabledenturehasanin- fluence on patient satisfaction. A comparative cross- over study has shown that, with respect to stability andretentionpoweraswellastheachievablepatient satisfaction, magnets are inferior to the fitting with ball-heads (Burns et al. 1995a, Burns et al. 1995b). A comparison of ball-head elements and over-denture attachments used for the fitting of an implant-re- tainedCoverdentureprosthesisdidnotshowanydif- ferencesintermsofpatientsatisfaction(MacEnteeet al. 2005); however, there proved to be a significant difference in the rate of technical complications. Withinanobservationperiodofthreeyears,prosthe- sis fitted with ball-heads required 6.7 repairs, whereas the group of bridge-fitted prosthesis re- quired 0.8 repairs per patient only. Hence, overden- ture attachments as fitting elements for removable The treatment of toothless jaws A case for CAD/CAM Author_Dr Sven Rinke, Germany Fig. 1