FPD — Tooth Preparation & Pontics
Abutment Selection
Ante's law: the combined root surface area of the abutment teeth should be equal to or greater than that of the teeth being replaced by pontics. Violating it risks abutment overload.
Finish Lines
- Chamfer — ideal for metal/PFM margins.
- Shoulder — for all-ceramic, gives bulk for esthetics.
- Knife-edge/feather — conservative but poorly defined; avoided for ceramics.
Pontic Designs
- Modified ridge lap — most hygienic esthetic pontic; ideal for the posterior maxilla / esthetic zone (tissue contact only on the buccal).
- Sanitary (hygienic) pontic — no tissue contact; used in the posterior mandible (non-esthetic).
- Ovate — most esthetic, needs a prepared ridge.
Principles of Preparation
Adequate but conservative reduction, ~6° total occlusal convergence (taper) for retention, rounded internal line angles, and a smooth finish line.
Exam Tips ⭐
Ante's law for abutment surface area; modified ridge lap = most hygienic esthetic pontic; sanitary pontic = posterior mandible.