Easier to prepare accurately
without trauma to the soft tissues.
Usually situated on hard
They can be easily finished.
They are more easily kept clean.
Impressions are more easily
made, with less potential for soft
Restorations can be easily
evaluated at recall appointments.
Dental caries, cervical erosion, or
restorations extend sub-gingivally, and a
crown lengthening procedure is not
The proximal contact area extends to the
Additional retention is needed.
The margin of metal ceramic crown is to
be hidden behind the labiogingival crest
It is also used to produce a cervical crown
ferrule on endodontically treated tooth.
Root sensitivity cannot be controlled by
more conservative procedures, such as the
application of dentin bonding agents.
Modification of the axial contour is
Fail to provide
adequate bulk at
margins (to enable
the wax pattern to be
distortion and to give
strength and, when
porcelain is used,
This margin is
used for full
crowns , small
Allows room for
for facial part of
An acute angle is
likely to chip.
margin deep into
It is less
Particularly suitable for
cast metal crowns and
the metal-only portion of
Tilting it away from the
tooth will create an
undercut; angling it towards
the tooth will lead to over-
reduction and loss of
Distinct and easily
identified, provides room
for adequate bulk of
Marginal accuracy depends
upon having high quality
diamond and a true running
Can be placed with
precision, although care
is needed to avoid
leaving a ledge of
Chamfer should never be
prepared wider than half
the tip of the diamond
an unsupported lip of
enamel can result.
Recommended for facial surface
of a metal-ceramic restoration
where a metal collar (as opposed
to a porcelain labial margin) is
Less preferred to
shoulder or sloped-
Removes unsupported enamel
and allows some finishing of the
Allows improved esthetics
because metal margin can be
trimmed down a knife-edge and
hidden in the sulcus without the
need for positioning the margin
closer to the epithelial
A beveled margin, under certain
circumstances, is more suitable
for cast restoration particularly
if a ledge or shoulder already
When access for
limited, there is
little advantage in
The objective in beveling is three
•To allow the cast metal margin to
be bent or burnished against the
prepared tooth structure.
•To minimize the marginal
discrepancy caused by a complete
crown that fails to seat
•To protect the unprepared tooth
structure from chipping (e.g. by
removing unsupported tooth
In cases of gingival
would lead to
extension of the
placement of the
margin on dentin
rather than on
I. Guiding grooves or depth orientation grooves (on
both facial and incisal surfaces).
II. Labial reduction (first gingival third and then incisal
III. Incisal or occlusal reduction (if required).
IV. Proximal reduction (not beyond contacts).
V. Lingual reduction (enhances mechanical retention
and increases surface area for bonding).
VI. Finishing of all prepared surfaces.
with a porcelain