Cantilever bridges (fixed-free)
In a cantilever bridge the pontic is attached to abutments on one side of the gap only; its other end is free. It saves preparing a tooth, but it is potentially destructive, because the pontic acts as a lever.
- In a fixed-fixed bridge, a force on the pontic is shared by the abutments at both ends.
- In a cantilever, the abutment next to the pontic becomes a fulcrum: it is pushed down and tipped toward the gap, while the far retainer is pulled away from its tooth, putting tension on the cement.
Making a cantilever work
- Strong abutments with long roots and healthy periodontium; usually two splinted abutments.
- Only one, small pontic, narrower than the lost tooth.
- Light contact in centric occlusion and no contact in side movements.
- Rigid connectors and well-retained full-coverage retainers.
Typical uses
- An upper lateral incisor held by the canine (forces in front are light).
- A first premolar held by splinted second premolar and first molar.
- A spring cantilever: an upper central incisor carried by a long, slightly springy palatal bar from premolar or molar abutments, used where a gap (diastema) is to be kept or the neighbours mustn't be prepared.