The Effect of Various Finish Line Configurations on the Marginal Seal and Occlusal Discrepancy of Cast Full Crowns After Cementation - An In-vitro Study
Background: The marginal fit of crowns is of clinical importance. It is found that marginal and occlusal discrepancies are commonly increased following cementation. The resistance of cementing materials is a factor that prevents cast restorations from being correctly seated. Different finish lin...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
JCDR Research and Publications Private Limited
2015-08-01
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| Series: | Journal of Clinical and Diagnostic Research |
| Subjects: | |
| Online Access: | https://jcdr.net/articles/PDF/6283/12574_CE[Ra1]_F(AK)_PF1(PAK)_PFA(AK)_PF2(PAG).pdf |
| Summary: | Background: The marginal fit of crowns is of clinical importance.
It is found that marginal and occlusal discrepancies are commonly
increased following cementation. The resistance of cementing
materials is a factor that prevents cast restorations from being
correctly seated. Different finish lines behave differently in
facilitating the escape of the cement. When the escape path of
the cement decreases, the crown fails to seat further.
Materials and Methods: This study was planned with an aim
to evaluate the effect of various finish lines on the marginal
seal and occlusal seat of full crown preparations. Six stainless
steel metal dies were machined to simulate molar crown
preparations. The diameter was 10 mm and height was 6mm.
The occlusal surface was kept flat and a small circular dimple
was machined for reorientation of the wax pattern and metal
copings, margins of various designs were machined accurately.
The margins prepared were Group A- 900
C shoulder, Group BRounded shoulder, Group C- 45 degree sloped shoulder, Group
D- Chamfer, Group E- Long chamfer, Group F- Feather edge.
Full cast metal crowns of base metal alloy were fabricated over
the metal dies. Zinc phosphate luting cement was used for the
cementation. After twenty four hours, the cemented crown and
die assembly were embedded in clear acrylic resin so as to hold
the assembly together while sectioning. Twenty four hours later,
all the samples were sectioned sagitally.
The sectioned halves were focused under a stereomicroscope
and the cement spaces were measured to the nearest micron.
The cement thickness was measured at two points on the
occlusal surface and one at each margin.
Results: Significant differences were observed in the occlusal
seat and marginal seal of all the finish line configurations.
The rounded shoulder had the best occlusal seat, followed by
900
C shoulder. The occlusal seat and marginal seal afforded by
the shoulder finish lines were similar whereas there was a vast
difference in the seating and sealing of long chamfer and feather
edged preparations. They showed the worst occlusal seat.
Conclusion: It was found that the finish lines like shoulder
preparations which exhibit poor sealing prior to complete
cementation allow good seating whereas margins which seal
earlier do not allow escape of cement and hence do not seat
completely. |
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| ISSN: | 2249-782X 0973-709X |