Pontic 42, labial view of single-winged bridge using implants) and also a combination using removable ( tissue-borne) restorations can help relieve the natural residual teeth. An increase in the number of abutments (e.g. However, for purely implant-borne fixed restorations in particular, a minimum of six abutments is required in the mandible and even eight abutments in the maxilla due to the lower bone quality. If restorations, which are removable for the patient, are retained on fixed crowns they are called fixed-removable restorations.Ī minimum of four periodontally healthy abutments in a favourable alignment (quadrangular) is essential for ensuring stable, statically balanced support per jaw for purely fixed restorations. by screw-retention or temporary cementation) but are designed to be removable by the dentist, are called ' operator-removable'. Restorations, which are fixed for the patient (e.g. In contrast to removable restorations, fixed restorations are rigidly bonded to teeth or implant abutments using adhesive retention or cementation. Implants replace 'fixed' tooth roots in the bone but are not defined as fixed restorations. In particular crowns (though they often do not replace a tooth but only supplement the lost tooth structure of an existing tooth) and bridges as well as bar restorations are described as fixed restorations. Fixed restorations are a part of prosthetics.