Cantilever dental bridge
In most of the cases, the pontic is positioned between the abutment teeth. However, in some clinical situations teeth may not be present on both sides of the toothless gap.
Cantilever bridges are dental bridges that are designed when abutment teeth are prepared on only one side of the missing toothless gap. In such cases, the pontic is located outside the abutment teeth.
When can such circumstances occur?
- when, for aesthetic reasons, it is not desirable to prepare teeth on both sides of the breach
- when no teeth exist on one side of the breach
- when the eligible abutment teeth on one of the sides is already supporting another prosthetic restoration that, for various reasons, cannot be replaced
Cantilever bridges involve increased, of the axis forces that will act on the abutment teeth (see image below).
Therefore, cantilever bridges should be carefully planned; otherwise, there is the risk of jeopardizing abutment teeth stability.
There are two types of cantilever bridges:
Cantilever bridge with the pontic placed towards the front of the mouth
This means that the gap is located in front (or anterior) of the abutment teeth. It is the favorable situation from the two because chewing pressures decrease as we advance towards the front of the mouth.
cantilever bridge with 3 abutment teeth and the pontic towards the front of the mouth
However, chewing forces are still acting outside the axis of the bridge, hence putting additional pressures on the abutment teeth. Therefore, the design should follow certain rules:
The pontic should only have a single artificial tooth (only one tooth should be replaced)
The prudent approach is to design a cantilever bridge when the missing tooth is either a premolar or a lateral incisor and only in limited situations if other teeth are missing.
Generally, at least two abutments are needed to support the bridge (although there are some exceptions if the abutment tooth is a strong canine or molar).
If we need to replace a premolar or molar, we must take into consideration that chewing pressures are higher on the lower arch.
There are two clinical situations when these restorations may be indicated:
When, for aesthetic reasons, it is not desirable to prepare a tooth located in a visible part
Observe the picture:
The first upper premolar is missing and the canine located at the front end of the gap is healthy and undamaged. For obvious aesthetic reasons, we want to leave this tooth untouched.
In this situation, we can design a cantilever bridge with the second premolar and the first molar as abutments (marked with arrows). These teeth are less visible compared to the canine and the aesthetic appearance will be somehow improved.
Note: Of course, the best solution for this particular case is a single dental implant which will avoid the need of preparing any teeth. Although this is very true, not everyone can afford such a restoration (or, in some places, there may be no technical capabilities for dental implants).
When the anterior abutment tooth is already sustaining another prosthetic restoration that, for various reasons, cannot be replaced.
Cantilever bridge with the pontic placed towards the back of the mouth
The toothless gap is located behind (or posterior) the abutment teeth. The chewing forces are much higher in the back part of the mouth. Consequently, the chewing forces that act on the abutment teeth, besides being of the axis, are also extremely high.
After a shorter or longer period of time, abutment teeth may become loose which may jeopardize the entire restoration.
cantilever bridge with pontic
towards the back of the mouth
There are few situations when these types of restorations may be indicated:
- temporary restorations
- if back teeth are missing and patients do not want (or cannot afford) more expensive restorations: removable dentures, dental implants
The lifespan and prognosis of these restorations are usually very short. With the development of dental implants, such solutions are rarely used.
Last review and update: November 2020