Removable Prosthodontics
Removable prosthodontics is tested through design decisions: which teeth and tissues carry the load and how the prosthesis is kept in place.
Classification and design
- Kennedy classes I-IV with Applegate's rules: missing third molars do not alter classification; the most posterior edentulous area determines the class; modifications count additional edentulous areas.
- Class I and II are tooth- and tissue-supported; Class III is tooth-supported, so the design must not overload abutments.
- Rests seat on prepared occlusal or cingulum seats; a circumferential clasp engages about 0.25 mm, a bar clasp approaches from the gingival third.
- Major connectors: a lingual bar needs at least 8 mm between gingival margin and floor of the mouth; otherwise use a lingual plate.
Complete dentures
- Border molding records the functional sulcus; the posterior palatal seal along the vibrating line improves retention.
- Balanced bilateral simultaneous occlusal contacts in excursion prevent tipping.
- The neutral zone is where tongue and cheek forces balance; teeth placed there improve stability.
- Combination syndrome: anterior maxillary resorption with mandibular anterior overeruption under a long-standing upper denture.
Worked example
A patient is missing 36 and 46 with all other teeth present. Each arch has a single bounded posterior space, so both are Kennedy Class III with no modification. Because the load is tooth-supported, the design uses mesial rests on 35 and 37 with cast circumferential clasps, not a stress-relieving distal extension design. The reasoning is load path, not custom.
Traps
Reclassifying when third molars are missing; placing a lingual bar in a shallow floor of the mouth; skipping rest seat preparation; assigning a distal extension design to a bounded saddle; ignoring vertical dimension in a worn dentition.