Bridges are used for replacing single or several missing teeth. Bridges are generally fixed but, in specific cases, also removable restorations (telescope bridges). Bridges are differentiated as single-span or long-span bridges according to the number of separate edentulous ridge segments they bridge. They can be supported on teeth, purely on implants (implant-supported bridges) or on teeth and implants (hybrid bridges)
Bridges are often retained on their anchors/abutments by (anchor-, abutment) crowns, but can also be retained using, e.g. inlays (inlay bridges, or adhesively bonded retention wings (adhesive bridge, acid-etched bridge, Maryland bridge) on one (single-winged bridge) or both (twin-winged bridge) adjacent teeth. Special systems use anchors adhesively bonded into holes drilled in the adjacent teeth.
All-ceramic, single-winged, free-end bridge
An essential component of a bridge is its pontic, which replaces at least one tooth. It is called a cantilever pontic if it is (in the case of a cantilever bridge) retained on one of the teeth adjacent to the space. Saddle bridges (fixed-fixed bridges) close tooth-bounded gaps between two anchors/abutments (teeth or implants) with one pontic retained on both abutments.
Zirconium dioxide free-end bridge on a stone model
The junction between the abutment crown and pontic is called a "connector". Its dimensions (apart from length of the span) are a decisive factor in ensuring the fracture resistance of a bridge.
Depending on the distance or amount of contact of the bridge pontic to the alveolar mucosa, bridges are referred to as self-cleansing bridges (with a "self-cleansing" pontic), sanitary bridges or tangential bridges. The periodontally unhygienic saddle bridge is no longer a relevant option. The ovate pontic is generally a convex egg-shaped pontic (with oval/ellipsoidal cross section) that appears to emerge from the alveolar ridge in the same way as a natural tooth, which is an advantage in terms of aesthetics.
A common path of insertion must be found for all abutments involved in order to fit a bridge. This is achieved by means of parallel preparation, separation of the bridge (sectioned bridge) by a slide attachment or telescope crowns as well as with implants using angled abutments, if necessary.
The bridge pontics and abutment crowns are collectively known as "units" of a bridge. This means that a full bridge (involving all teeth in one jaw) can be a maximum of 16 units.
4 unit VMK bridge
All the materials and procedures used with crowns can be used for fabricating and retaining bridges. Glass-fibre ribbons, with which pontics can be contoured and/or reinforced/retained, can also be used for temporary bridges.
For reasons of stability the number and total root surface of the bridge pontics must be at least as large as those of the teeth to be replaced. The flexibility of the bone segment of the mandible can lead to complications involving decementation of individual bridge abutment crowns.