Removable Prosthodontics: Complete and Partial Dentures
What is examined
Design, construction sequence and biomechanics of complete and partial dentures - how support, retention and stability are built in, and how frameworks are designed on a surveyable cast.
Complete dentures
- Sequence: primary impression, custom tray, border moulding, wash impression, master cast, record bases and occlusion rims, jaw registration, tooth set-up, try-in, flasking, packing, curing, deflasking, finishing, remount and occlusal adjustment.
- Support comes from the denture-bearing area, retention from the border seal and polished surface contour, and stability from the fit and occlusion.
- Balanced occlusion means simultaneous working and non-working contacts in eccentric movement. Lingualised occlusion narrows the occlusal table for severely resorbed ridges.
Partial dentures
- Kennedy Class I–IV, refined by Applegate's rules; modifications are counted, not the number of edentulous spaces.
- Rests direct load along the long axis of abutments; clasps provide retention, bracing and reciprocation.
- RPI design (mesial rest, proximal plate, I-bar) reduces torque on abutments compared with a cast circumferential clasp.
- Survey to establish the path of insertion, then block out undercuts, relieve gingival margins and duplicate for the refractory model.
Worked example
A mandibular Kennedy Class I case has no distal abutment, so the base will rotate about the last rest when loaded. Design mesial rests, a lingual bar and a functional (altered cast) impression of the saddle so the tissue surface is recorded under load rather than at rest.
Traps
- Counting a modification as a class - a Class II modification 2 is not a Class IV.
- Leaving blockout wax too thick so the framework rocks on the teeth.
- Processing without adjusting the incisal pin, building in a posterior interference.
- Ignoring the neutral zone, producing a tongue-driven lower denture.