implants UK - the journal of oral implantology

16 I Iresearch _ Toothless jaws implants1_2011 _Prosthetic devices can be fitted in various ways. Digital technologies have left their mark in implantology and provide options for high quality so solutions. Classical indications for implant-prosthetic treatments include dentures for the toothless jaw. For this type of denture, clinical studies document a high survival rate of about 85 to 90 per cent with observation periodsofupto20years.1,2 Various prosthetic concepts have established themselvesforthefittingofsuperstructuresaccording tothenumberofinsertedimplants.3 Generally,thereis eitherafixeddenturemountedonsixtoeightimplants andbornebytheseonly,oraremovabledenturewitha reducednumberofimplants. The selection of a suitable denture depends on subjectivecriteria(patientexpectations,financialcon- straints) and on clinical aspects (anatomic criteria, technicalandclinicalreliabilityofimplantsandsuper- structure). Accordingly, the success of the prostheses dependsonthefollowingfactors(Fig.1): _subjectivecriteria(patientsatisfactionandquality oflife); _objectivecriteria(probabilityofsurvival);and _necessarymaintenanceeffortduringthelifetime ofthedenture. _Criteria for the selection of type of denture Fixed, as well as remov- ableimplant-prostheticden- tures in the toothless jaw, as opposed to the conventional full denture, have proven to significantly increase pa- tients’ satisfaction and im- prove their ability to chew.4,5 Hence, the insertion of two to four implants can lead toaclearimprovementofqualityoflife.Therefore,the removable implant-supported and implant-retained cover denture prosthesis is nowadays considered an effectivetherapy. However, there was also evidence that, in par- ticular, the choice of fitting elements in a removable denture,forexamplemagnets,ball-heads,bridgesand telescopes, has an influence on patient satisfaction. With respect to stability and retention power, as well asachievablepatientsatisfaction,acomparativecross- over study demonstrated that magnets are inferior to the fitting with ball-heads.6,7 A comparison of ball head elements and overdenture attachments used for the fitting of an implant-retained cover denture prosthesis did not demonstrate any differences with regard to patient satisfaction.8 However, there proved to be a significant difference in the rate of technical complications. Within an observation period of three years, pros- theses fitted with ball-heads required 6.7 repairs, whereasthegroupofbridge-fittedprosthesesrequired 0.8 repairs per patient only. Hence, overdenture attach- ments as fitting elements for removable superstruc- tures guarantee high patient satisfaction. Owing to their low rate of technical complications, they require less maintenance than alternative fitting elements, 8 which is an important criterion for the long-term suc- cessoftheprosthesis. High maintenance requirements demand more practice visits and take the time of both the patient and the care provider. Furthermore, if there are technical complications that have led to the failure of superstructure elements, an intervention by a den- tal technician might be necessary to reconstruct or replace individual components. This is also connected withadditionalcostsinordertomaintainfunction. Fig. 1_Subjective and objective prosthetic success criteria. The treatment of toothless jaws—A case for CAD/CAM Author_Dr Sven Rinke Fig. 1