Margin Integrity
Sub gingival margins
can be assessed by
radiograph
Marginal integrity can be assessed
by moving a sharp explorer from
the restoration to the tooth and
from the tooth to the restoration
(open margin= 50 µm the tip of
sharp explorer can be inserted
between the restoration and the
tooth).
Microscopic Examination
Casting beyond
finish line
(over extended)
due to
Over
waxed/flash of
wax during wax
build up
Types of Marginal Defects
A.
B.
C.
D.
Over extended vertically
Short margin(under extended)
Over extended horizontally(over contoured)
Open margin
Types of Marginal Defects and their causes
1. Open margin
– Casting not completely seated
– Improper impression
2. Shoulder or ledge(under extended horizontally)
– Overpolished casting
– Improperly trimmed die
3. Casting beyond finish line (over extended)
– Overwaxed/flash
– Improperly trimmed die-over trimmed
4. Short margin
– Improper impression
– Over trimmed die
– Over carving of wax pattern
– Over polishing of casting
Types of Marginal Defects
Open Margin:
• Missing margin
– Incomplete impression
– Improperly trimmed
die
– Incomplete casting
• Error in waxing
• Error in casting
– Over polishing the
casting
Marginal discrepancy caused by an overextended margin;
can be corrected?????
a) Marginal discrepancy
caused
by an overextended lingual
margin;
b) Reduce the overextension
from
the axial surface not from
underneath;
c) If overextended margin
removed incorrectly, this
results in a deficient margin
Burnishing of slightly open gold rest.
Margins using burnisher
Failures result from incorrect margin
•
•
•
•
Looseness of
crown
Cervical caries
Injury to the
gingival tissue
Poor esthetics
All Ceramic crown
All metal crown