I 15 case report _ toothless jaws I CAD/CAM 2_2010 there are individually shaped bar attachments, and on the other hand, there is the classic round bar, which can be manufactured either by casting or by combination of pre-fabricated elements. The overdenture attachment fitted on four implants is a classic fitting element for a purely implant-supported cover denture prosthesis in a toothless upper or lower jaw. A retrospective study with 51 patients compared individually shaped bar attachments and round bars for the fitting of cover denture prostheses.9 Twenty-six patients were equipped with round bars, while 25 patients received a superstructure with an individual bar attachment on four implants each. After a sur- veillanceperiodoffiveyears,thesurvivalrateofthe implantswas100%.Largertechnicalcomplications that required a renewal of the mounting elements occurred in the round bars only in the form of frac- tures in the extension areas. The fractures on the extensions of the overdenture attachments, which were exposed to high mechanical stress, were due either to porosities in the cast object or to inhomo- geneities in the area of the points of attachment. Furthermore, it was determined that low-grade complications (activation of hanks) occurred three times as often in the round bars as in the bar attachments. Thus, two causes of defects can be deduced: firstly, defects due to faults in the manu- facturingtechnique(castingandjoiningprocesses); and secondly, defects causatively connected with the design of the superstructure. Two versions are described in the literature for the fitting of attachments in the toothless upper jaw: the fitting of attachments on four implants in the anterior segment and the fitting of two attachments on three to four implants on the lat- eral segments (mostly after a previous sinus floor augmentation). Additionally, for the application of attachments in the toothless upper jaw, data from clinical studies has been published.9 Both attach- ment concepts featured almost identical survival rates after five years: 98.4 % for the attachments in the anterior segment and 97.4 % for the attach- ments fitted on six to eight implants in the lateral segments of the upper jaw. In particular, fitting by bar attachments appears tobeatherapeuticmeanswithguaranteedsuccessof thefittingofpurelyimplant-supportedcoverdenture prostheses in the upper and lower jaw. It excels with a low rate of technical complications, as well as low maintenance requirements. Hence, bar attachments constitute clinically tested fitting elements for im- plant-retained and implant-fitted removable super- structures in the toothless upper and lower jaws. No clinical data for the fitting of removable super- structuresinthetoothlessupperjawformagnetsand for ball-head attachments is available. Additionally, the application of so-called locators for the fitting ofremovableimplantsuperstructurescannotbecon- sidered to be based on evidence, according to the currently available data. To date, no results of clinical studies have been presented for this fitting element. Telescopes as fitting elements for removable superstructures are popular particularly in the Ger- man-speaking countries, as they are very hygienic and easy to expand. However, these advantages are offset by the high technical requirements and costs. Clinical studies on the suitability of double crowns as fitting elements in implant prostheses demon- strate that they are generally suitable and they point out the advantage of combining the natural teeth with implants for the fitting of a removable con- struction, as opposed to attachments. Fig. 2_Fracture of a bar attachment construction manufactured by casting in the area of the extension. Fig. 3_Casting of the implants in the pick-up technique with a high strength casting material. Fig. 4_Tooth arrangement produced on the work model. Fig. 5_Virtual construction of the bar attachment construction with distal attachments. Fig. 5Fig. 4 Fig. 3Fig. 2