Tunnel cavity
design
The problem with this design is the potential
for lowering the strength of the marginal ridge. If the lesion
is more
than 2.5mm from the crest of the ridge and the access cavity
through the occlusal surface is kept to a minimum this can
be a very conservative and aesthetic restoration.” |
 |
Lab-
In this laboratory series there is a small proximal lesion
identified
radiographically on the distal of the first molar. The decision
to regard the lesion as Size1 rather than Size 0 will be
taken following separation to identify the presence or absence
of cavitation.” |
 |
Lab-
The teeth were separated using a small orthodontic rubber separator ring and a small discrete impression taken
of the interproximal space using a rubber base impression
material. |
 |
Lab-
Careful examination
of the surface of the impression shows there is actual cavitation
in the enamel and therefore some limited degree of surgical
intervention is justified. |
 |
Lab-
To prove the
point the model is dismantled to show the proximal surface
with the limited cavitation. Note that the lesion is more
than 2.5mm. below the crest of the marginal ridge. |
 |
Lab-
A tunnel cavity
has been prepared and restored with a high strength auto-cure
glass-ionomer. |
 |
Lab-
The model has
been dismantled again to show the ultimate restoration. Note
the demineralised enamel surrounding the glass-ionomer. This
is still smooth and hard, though stained and disfigured, so
it may remain and will remineralise. Note that the strength
of the marginal ridge has not been compromised with this design. |
 |
Lab-
The tooth has
now been sectioned to demonstrate the cavity design. Note
that the cavity floor is no closer to the pulp than it would
be if a standard Class II GV Black cavity had been cut. |
 |
Clinical
Bitewing radiographs
taken in a clinical case showing a lesion at the distal of
the upper first molar. It was apparent that a tunnel cavity
was indicated. |
 |
Clinical
A standard tunnel
cavity has been prepared and is ready to be restored with
glass-ionomer. |
 |
Clinical
The completed
restoration using an early version of a Type II.1 restorative
aesthetic glass-ionomer. As there was a risk of early water
contamination it had to be sealed with an unfilled resin immediately
after the cement had set. |
 |
Clinical
Placement was
apparently successful because this is the same restoration
12 years after placement. |
|
|
 |
This is the first
of a laboratory series showing the design of a slot cavity.
Note the presence of the lesion on the distal of the first bicuspid.
|
 |
The lesion is
very close to the marginal ridge and it is apparent that it
would collapse if a tunnel design was utilised. |
 |
The reassembled
model showing the design of the cavity. It is limited to the
extent of the demineralisation only so there is still a tooth
to tooth contact towards the buccal. This will make it easier
to maintain a sound contact between the teeth. |
 |
The tooth has
been removed from the model to show the design of the final
cavity. Note that there is demineralised enamel surrounding
the cavity that is expected to remineralise in the absence
of disease. Depending upon the occlusion it is possible to
restore this cavity with glass-ionomer only or else it can
be based with GIC and laminated with composite resin. |
|
|
 |
The proximal
approach lesion can only be restored if there is a large cavity
already present in the adjacent tooth. In this case the presence
of the Site 2, Size 1 lesion was identified on the radiograph.
It was clearly revealed following removal of a large Site
2, Size 3 amalgam that was due for replacement dentistry. |
 |
Access is gained
through the Size 3 cavity. Visibility is often limited but
preservation of the marginal ridge is desirable. |
 |
The completed
cavity design. Note that there is still demineralised enamel around the periphery and probably some softened dentine on the axial wall. However, once sealed with a bioactive glass- ionomer these areas will remineralise. |
 |
The completed
restoration using a high strength auto cure glass-ionomer
that is radiopaque. Note the surrounding demineralised enamel
that is quite smooth and is expected to remineralise in the
absence of disease. |
