How Long Do Dental Bridges Last?

There is no exact
figure regarding the success rate of crown and bridges. According to
some surveys, small conventional bridges can last around 20-40 years
where as larger conventional bridges can last 10-30 years. For adhesive
bridges, they last approximately 10-20 years or more.  Evidences to
prove the success rate for adhesive bridges are not very strong due to
they are being introduced long time after conventional rate.  Success
rate of bridges depend strongly on the maintenance by the patient
him/herself.

There are few causes of failure of bridges:

1)      Loss of retention

Retainer
of the bridges (which is the metal part that you can observe from your
bridges) which became loose after some time might cause the failure of
the fixed prosthesis. Furthermore, plaque might accumulate at the area
and caries can develop at the surface of tooth preparation. To check
whether the bridge retainer is loose, your dentist will press the bridge
up and down, if there is looseness, there will be small bubbles at the
margins of the retainers.

For adhesive bridges, recementation of
bridges are possible but you must be reminded that there is a
possibility that it will come off anytime later.

2)      Mechanical failure

Porcelain
fracture:  It is very common, for short term wise, one of the solution
is to replace the fracture part with composite as it is more cost
effective for the patient but the composite will be discolored after few
years and it might be a hazard for the patient to replace the
restoration.

To avoid this problem, the metal of the bridge should be adequate thickness to avoid distortion.

3)      Failure of connectors

Connectors
are the one who join the pontic (artificial tooth) to the retainer
(crown/other restoration that is cemented to the abutment). Failure of
connectors might be the failure of the metal itself or failure to bond
to the metal framework. Normally the whole bridge must be remove and
remade for this situation.

4)      Distortion

Distortion
of bridges can occur due to trauma and thin framework or inadequate
length of framework for a large space / span to be replaced.

5)      Occlusal wear and perforation

This
might happen after the bridge is constructed for a long time. Normally
dentist will place an appropriate restoration on the perforation.

After
a long time, periodontal disease might have developed around the
abutment teeth. For early periodontal disease, no treatment is needed
but for advanced periodontal disease, the bridge should be removed. No
bridge should be constructed for patients who have excessive bone loss
and advanced periodontal disease because prognosis for the bridge will
be poor.

The tooth might be non-vital after being prepared. Root
canal treatment can be done might accessing from the top of the crown
but the overlying crown might mask the real anatomy of the underlying
tooth and by accessing the crown, it might weaken the core. For teeth,
which has been root filled before, if there is problem, shortening of
the roots might be a good idea.

As we had mentioned earlier,
caries might develop at the surface of tooth which has been prepared.
Movement of the abutment tooth might occur after sometime, due to
periodontal disease and the bridge might become loose.

Sometimes,
it might be a failure from the beginning where the constructed bridge
is not well adapting to the prepared tooth. Marginal deficiencies of the
bridge may occur or there’s defect on the bridge at the time it was
being constructed. The design of the bridge might be poor at first. This
can or contribute to the bridge failure.

The severity of bridge
failure is accessed before the dentist determine whether replacement /
adjustments are to be done. Sometimes, it is best to leave it alone if
it doesn’t cause harm or damage. Small repairs can be done and it is
cost effective, such as amalgam on the surface of metal retainer,
composite on the porcelain but dentist should always check the restored
part periodically. If the bridge has to be removed, multiple parts of
the bridge can be divided to smaller sections to ease the removal.  If
the abutment tooth is to be extracted, we can just remove using a bridge
removal as it is faster. For bridge to be removed intact, we can try to
remove using a sharp tapping to fracture the cement lute or using slide
hammer to remove it. Methods to remove bridges depend on the dentist
him/herself.

To conclude, success of a bridge depends on several
parties. Cooperation from the patient, good clinical skills from the dentist, good laboratory work from the technologist.