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implants international magazine of oral implantology

I research 12 I implants2_2012 placed on the tube bar prior to seating the E clip to ensure vertical resilience. The spacer ensures a slight gap between the E clip and the tube bar so that when the patient bites down, the E clip does not overload or distort the bar as the denture beds into the supporting mucosa. All undercuts around the bar assembly, especially between the bar clip andtissues,wereblockedoutwithasiliconemate- rial(Fig.10).Awindowwasthencutintothelingual aspectofthedenturetoexposetheEclip(Fig.13a). A small bead of cold-cure acrylic resin was then placedontheEclip,coveringtheretentiveelement oftheclip.TheEclipwasthenattachedtotheden- ture with small increments of resin (Fig. 13b). The resin was allowed to cure fully before the denture with the E clip was removed from the mouth. The remainder of the void was then filled with cold- cure resin and allowed to cure outside the mouth (Figs. 13c & d). Ideally, this process should take place in a pressure pot. A transfer jig that fits into the E clip and is ef- fectively a tube bar replica can be utilised if a large volumeofacrylichasbeenusedtohousetheEclip. ThedenturewiththetransferjigseatedintheEclip is bedded into a patty of fast-set plaster, similar to a denture-repair scenario. Once the stone has set, the denture is placed in a pressure pot with warm water and the self-curing resin is allowed to poly- merise. Once the acrylic has fully cured, it is sepa- rated from the stone base and the transfer jig and all excess acrylic is trimmed. At least 50% of the lamellae of the E clip must be clear of resin. Only the superior part of the E clip with the attachment portion and shoulder section is locked into acrylic (Fig. 13c). The lamellae must be free to flex over the tube bar during insertion and removal of the denture. If the resin is in direct contact with the lamellae, the denture may not seat, as the E clip cannot flex. Finally, the definitive prosthesis was seated (Figs. 14a & b). The level of retention of the E clip was adjusted using the acti- vation and deactivation tools provided in the restorative kit. The occlusion was checked and ad- justed after verifying that the denture had been properly seated, using pressure-indicating paste. The bar assembly is required to retain the denture in the two-implant scenario. Support is derived from the conventional hard- and soft-tissue load, bearing areas like the residual ridge and the buccal shelf.Thepatientwastheninstructedonappropri- ate care of the implants and the prosthesis, and a routine recall and maintenance programme was instituted. _Discussion It is imperative that the block-out procedure around the bar assembly is correct. Otherwise acrylic will enter an undercut area and cure, thus locking the denture to the bar assembly. As a con- sequence, there would be no option but to cut the denture from the bar to free it. This will not only ruin the denture, but may also damage the bar—a verycostlyandtime-consumingmistake.TheEclip is designed for use with the two-implant bar and should be picked up with a self-curing resin as ex- plained. The T clip is for a laboratory-processed dentureonfourormoreimplants,astheplasticin- Fig. 13a Fig. 13b Fig. 13c Fig. 13d