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- Anesthetize area if indicated.
- Take preliminary impression.
- Select gingival, body and incisal shades of teeth to be restored
(NOTE: Best accomplished after old amalgam is removed).
- If near pulp exposure, place small amount of calcium hydroxide
in deepest area of preparation.
- Prepare teeth as follows:
- On posterior teeth, except where esthetic results are important,
a metal gingival collar is suggested. This is more hygienic
and also kinder to the periodontal membrane by creating a smoother
transition from tooth to crown. Margins can also be burnished
closed in the event a minor discrepancy should occur.
- Ensure crown preparation has sufficient reduction (suggested
minimum 1.5 - 2.0 mm) for a strong and beautiful porcelain occlusal
surface.
- Ensure a minimum labial reduction of 1.5 mm (insufficient
labial reduction can cause poor translucency, bucked centrals
and angry patients).
- For a porcelain to margin finish, prepare a chamfered shoulder
.5 mm sub-gingivally on the labial aspect of the tooth. Tissue
must be retracted during impression so that the resultant die
is a complete reflection of the prepared shoulder.
- For superior esthetics, you may wish to select a PORCELAIN
BUTT MARGIN (combines strength of PFM crown with esthetics of
complete porcelain labial margin). Eliminates shadow effect
due to underlying metal substructure showing through thin, friable
soft tissue at gingival margin or exposure of metal collar due
to gingival recession. End lingual metal collar midproximally
(particular case situations may dictate other locations), labial
metal is cast only to axiogingival line angle. Porcelain margin
should be finished with either a 90-degree or sloped shoulder
while lingual metal margin should be prepared with a chamfer
or shoulder bevel.
- Ensure there is an adequate path of insertion.
- Take final impression with Panasil vinyl polysiloxane impression
material.
- Secure and trim an adequate interocclusal record (Regisil or
similar material).
- Cement temporary restoration.
- Prepare detailed lab prescription with details re: opposing
teeth, age and sex of the patient, amount of occlusal staining
required, and individual characterization needed.
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| Facial,
lingual and proximal surfaces may be reduced a minimum of 1.0-1.5
mm. Incisal or occlusal reduction should allow for no less than
2 mm porcelain in final restoration. |
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