Fixed partial dentures that attach to implants must support the lip in the same manner as that required of prostheses attaching to natural teeth. With completely edentulous patients, the prosthetic teeth and base must appropriately support the facial soft tissues in accordance with the criteria used for conventional complete dentures. The clinical and laboratory steps required to locate the most appropriate prosthetic tooth positions are the same as that used with conventional complete dentures (esthetics, tooth-lip relationships, phonetics, anatomic landmarks, occlusal vertical dimension, and muscular neutrality (neutral zone).
One of the deficiencies that can occur with fixed complete dentures is a lack of adequate support for the facial soft tissues since the cervical aspect of the prosthesis does not have border extensions similar to that of a complete denture. To provide proper facial support, a more substantial denture base may be needed, necessitating the use of an implant overdenture as opposed to a fixed complete denture.
It is important to determine how much of the teeth and soft tissue are visible during a maximal smile. As with conventional single crowns and fixed partial dentures, the display of significant amounts of soft tissue increases the esthetic difficulty of implant single crowns and implant fixed partial dentures. With fixed complete dentures, patients may smile in a manner that the border of the prosthesis would be visible, producing an undesirable esthetic result and necessitating the use of an implant overdenture.