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USE OF FUSED PORCELAIN IN FILLING TEETH 295
edge strength of porcelain is no greater than full length enamel
rods.
The Cavo-surface Angle should be that which the cleavage of
the enamel gives, or about a right angle. Its greatest disadvan-
tage is the fact that the inlay must be set upon unclean walls as
the whole process must be done under moist conditions; moisture
being necessary to maintain the color of the teeth while trying to
imitate their shade. This prevents the placing of the filling upon
freshly cut surfaces which have not been moistened, the greatest
enemy to all inlay fillings.
Another disadvantage is that the retention of the porcelain de-
pends upon the integrity of the cement, which is not wholly pro-
tected at the margins. While porcelain inlays fit the cavity from
a practical standpoint, the fact exists that they never exactly fill
the cavity, the cement taking up the space resulting from the mis-
fit, and is exposed in proportion to the amount of existing space
at the margins.
Indication for Porcelain Filling. Porcelain is indicated in the
following
In cavities in the anterior location in the mouths of patients who
have an appreciation for esthetic qualities of dental operations.
In cavities of Class One when they occur in defects on labial
surfaces.
In cavities of Class Three when much of the labial wall is gone
and rather strong lingual wall remains.
In cavities of Class Four, plan three, vital teeth with rather
thick incisal edge, not subjected to great stress in articulation.
In cavities of Class Four, plan one, when proximating tooth is
not in position as when the missing tooth is worn upon a plate or
is to be subsequently replaced with a crown or bridge.
In cavities of Class Four, plan four, in upper teeth when the
lingual surface does not articulate.
In gingival third (Class Five) in anterior teeth exposed to view
when patient smiles.
In cavities of Class Six on the six anterior teeth, Avhen the porce-
lain is built to a thickness of at least two millimeters, and in pulp-
less lower molars, restoring the entire occusal surface.
Contraindications. Porcelain is not indicated in the cavities not
above mentioned, and in all locations subject to great stress and
where good access form is difficult to obtain.
USE OF FUSED PORCELAIN IN FILLING TEETH 295
edge strength of porcelain is no greater than full length enamel
rods.
The Cavo-surface Angle should be that which the cleavage of
the enamel gives, or about a right angle. Its greatest disadvan-
tage is the fact that the inlay must be set upon unclean walls as
the whole process must be done under moist conditions; moisture
being necessary to maintain the color of the teeth while trying to
imitate their shade. This prevents the placing of the filling upon
freshly cut surfaces which have not been moistened, the greatest
enemy to all inlay fillings.
Another disadvantage is that the retention of the porcelain de-
pends upon the integrity of the cement, which is not wholly pro-
tected at the margins. While porcelain inlays fit the cavity from
a practical standpoint, the fact exists that they never exactly fill
the cavity, the cement taking up the space resulting from the mis-
fit, and is exposed in proportion to the amount of existing space
at the margins.
Indication for Porcelain Filling. Porcelain is indicated in the
following
In cavities in the anterior location in the mouths of patients who
have an appreciation for esthetic qualities of dental operations.
In cavities of Class One when they occur in defects on labial
surfaces.
In cavities of Class Three when much of the labial wall is gone
and rather strong lingual wall remains.
In cavities of Class Four, plan three, vital teeth with rather
thick incisal edge, not subjected to great stress in articulation.
In cavities of Class Four, plan one, when proximating tooth is
not in position as when the missing tooth is worn upon a plate or
is to be subsequently replaced with a crown or bridge.
In cavities of Class Four, plan four, in upper teeth when the
lingual surface does not articulate.
In gingival third (Class Five) in anterior teeth exposed to view
when patient smiles.
In cavities of Class Six on the six anterior teeth, Avhen the porce-
lain is built to a thickness of at least two millimeters, and in pulp-
less lower molars, restoring the entire occusal surface.
Contraindications. Porcelain is not indicated in the cavities not
above mentioned, and in all locations subject to great stress and
where good access form is difficult to obtain.
