Prosthodontics (Fixed and Removable)
This domain tests tooth preparation principles, impression and cementation choices, removable partial denture design and complete denture occlusion, with emphasis on the design decisions examiners can mark objectively.
Fixed prosthodontics
- Total occlusal convergence of 10 to 20 degrees gives retention and resistance without over-reducing the tooth.
- Ante's law, that abutment root surface must equal or exceed the root surface of the replaced tooth, is a useful rule of thumb rather than a law; splinting and implant support change the calculus.
- A post is indicated only when coronal structure is insufficient; retain 4 to 5 mm of apical gutta-percha and avoid posts in thin, flared roots.
Removable partial dentures
- Kennedy classification is set by the most posterior edentulous area. Under Applegate's rules the classification is recorded for the arch as it will be after planned extractions; third molars are not counted, and a second molar not to be replaced is not counted.
- Components: rests for support, minor connectors, major connector, direct retainers, and an indirect retainer placed anterior to the fulcrum line on the opposite side.
- Distal extension saddles are corrected with the altered cast technique.
Complete dentures
Border molding, posterior palatal seal, neutral zone and bilaterally balanced occlusion in eccentric positions are the examinable core. Denture stomatitis is managed by nocturnal removal, hygiene and topical antifungal therapy.
Worked example
A mandibular arch is missing the second premolar and both molars on the right, and the first molar only on the left. That is Kennedy Class II, modification 1: one posterior edentulous area plus one additional edentulous area. The fulcrum line runs through the most posterior right abutment and the left first molar; an indirect retainer is placed on the left premolar or canine rest.
Traps
- Classifying before planned extractions.
- Omitting the indirect retainer.
- Delivering a complete denture without balanced occlusion.