Introduction
Retainers hold the bridge; pontics replace the lost teeth. Each has its own design rules, and getting them right decides retention, hygiene and appearance.
Retainers
Requirements
- Retention and resistance greater than for a single crown, because the retainer also carries the pontic's load and leverage. Full crowns are the strongest retainers; partial crowns suit short spans and sound abutments.
- Common path of insertion: all abutment preparations must be parallel to each other, so the bridge seats in one direction without undercuts.
- Marginal fit and contours as for any crown.
- Rigidity to resist bending; enough metal thickness at the connectors.
- Esthetics in visible areas: metal-ceramic or all-ceramic retainers in front.
Choosing the retainer
Pontics
A pontic can never be an exact copy of the lost tooth: after extraction the ridge resorbs and remodels. It is designed for three things at once: function, hygiene and appearance.
Requirements
- Restores chewing and appearance, with an occlusal table narrower than the original tooth.
- Its ridge surface is convex, highly polished or glazed, and presses nowhere on the mucosa.
- Leaves the patient a way to clean underneath it with floss or a brush.
- Open embrasures and a smooth, slightly convex lingual surface, to avoid food traps.
- Rigid, and strong enough not to fracture or debond its veneer.
Gold, ceramic or highly polished metal on the tissue surface collects the least plaque; acrylic resin the most.