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1
FULL VENEER CROWN PREPARATION
“That which is finished today has little inherent value, only over time will it become invaluable as a work of art.”
FULL METAL CROWN OCCLUSAL REDUCTION
Planar reduction is started using a medium coarse tapered round ended diamond (6856-016)
Objective is to achieve reduction of the occlusal contours producing planar surfaces
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FULL METAL CROWN OCCLUSAL REDUCTION
Make depth orientation grooves on each triangular ridge and each primary developmental groove on facial and lingual
inclines
FULL METAL CROWN OCCLUSAL REDUCTION
Reduction of lingual cusps to 0.8 mm (non-functional cusp)
Depth orientation grooves on facial cusps are initially placed at 1.2 mm (functional cusp)
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FULL METAL CROWN OCCLUSAL REDUCTION
Comparing the depth groove to the measured
diameter of the diamond bur as a
gauge
Also a 1.0 mm or 1.5 mm enamel chisel can be used to judge depth of depth orientation grooves
FULL METAL CROWN OCCLUSAL REDUCTION
Final refinement of occlusal reduction will be done with
final finish
Occlusal reduction generally establishes the planes while initiating reduction
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FULL METAL CROWN OCCLUSAL REDUCTION
Check occlusal clearance with strip of red rope wax and compare translucency of imprints of cusps-look for areas that are too thin - the handle helps orient wax bite
facial
FULL METAL CROWN FUNCTIONAL CUSP BEVEL
Placed with medium coarse round ended tapered diamond (6856-016)
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FULL METAL CROWN FUNCTIONAL CUSP BEVEL
Place depth reduction grooves at 1.2 mm on functional cusp, tapering gingivally to no reduction at the junction of the upper 1/3 of facial cusp
FULL METAL CROWN FUNCTIONAL CUSP BEVEL
Chisel can help to determine if the amount of reduction is close to 1.2 mm paralleling the angle of the opposing occlusal cusp incline
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FULL METAL CROWN FACIAL & LINGUAL AXIAL REDUCTION
Use medium coarse tapered torpedo-ended diamond (6877K-014) bur
Produces a distinct crisp chamfer finish line
FULL METAL CROWN AXIAL REDUCTION
Facial reduction maintained vertical without over-tapering
Lingual reduction the bur is kept vertical without over- tapering and still creating a definite chamfer
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FULL METAL CROWN AXIAL REDUCTION
Facial and lingual reductions are carried into the proximal with out damaging adjacent teeth to create an island of tooth structure between each adjacent tooth
FULL METAL CROWN PROXIMAL REDUCTION
Initial prep is started with with medium coarse needle diamond (852-012)
Second part with medium coarse flame diamond (862-010) and fine flame diamond (8862-010)
Last with medium coarse tapered torpedo-ended diamond (6877K-014)
Needle Flame Chamfer
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FULL METAL CROWN PROXIMAL REDUCTION
Initial prep with medium coarse needle diamond (852-012) moved in up and down sawing motion until the contact is opened
Objective is to open the mesial and distal enough to be able move to the medium coarse flame diamond (862-010)
FULL METAL CROWN PROXIMAL REDUCTION
Initial preparation with medium coarse needle diamond (852-012) will partially open the contact, but not allow the medium coarse round ended diamond (6877K-014) to fit
Second step is to open space with tapered medium coarse flame diamond (862-010) and fine flame diamond (8862-010) to begin to form the chamfer line
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FULL METAL CROWN PROXIMAL REDUCTION
Lastly use the medium coarse tapered round ended diamond (6877K-014) to refine the finish line
The chamfer finish line is refined at 0.5 mm above the gingival crest in the proximal on mesial and distal surfaces
FULL METAL CROWN PROXIMAL REDUCTIONS
Common error made is to produce a “scallop” at each line angle where the diamond is not brought completely through at the same level
Using a periodontal probe check the draw path between facial and lingual axial reductions
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FULL METAL CROWN Final Finishing
Use fine round ended tapered diamond (8856-016) to go over the occlusal surfaces
Remember when finish lines that are cut with medium or coarse grit diamonds always need smoothing with fine grit diamond
They retain enough microscopic roughness to help to retain the restoration, yet appear smooth visually
FULL METAL CROWN Final Finishing
Use fine tapered round ended diamond (8856-016) to go over the occlusal surfaces to refine planar shape
Final depth of reduction should be defined at this point to 1.0 mm on lingual non-functional cusp and 1.5 mm on facial functional cusp
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FULL METAL CROWN Final Finishing
Use fine tapered round ended diamond (8856-016) to go over the functional cusp to smooth and finalize reduction of incline to 1.5 mm at the cusp tip
FULL METAL CROWN Final Finishing
Use fine tapered torpedo-ended diamond (8877K-014) to smooth and define final chamfer finish line on facial
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FULL METAL CROWN Final Finishing
Use fine tapered torpedo-ended diamond (8877K-014) to smooth and refine final chamfer finish line in the proximal surfaces
Use fine tapered torpedo-ended diamond (8877K-014) to smooth and refine final chamfer finish line on lingual
FULL METAL CROWN Final Axial Reductions
Final chamfer finish line is adjusted to the height of gingiva at 0.5 mm from the gingival crest
Final preparation axial reductions should be about 6-8 degrees of total occlusal convergence to allow for proper path of draw of restoration
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FULL METAL CROWN SEATING GROOVE
The initial seating groove is placed using the 169L as a guide
Place groove to full diameter of 169L carbide bur checking the draw against the mesial and distal surfaces
FULL METAL CROWN SEATING GROOVE
Also can check vertical alignment of seating groove using a periodontal probe placed into groove compared to mesial and distal taper
Hold 169L carbide bur against the mesial and distal taper before placing the groove
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FULL METAL CROWN SEATING GROOVE
After 169L, groove is enlarged/adjusted following the overall draw to the full depth of 171 carbide bur
Groove should extend to 0.5 mm above chamfer finish line and a definite gingival seat created
FULL METAL CROWN The Final Preparation
All line and point angles should be blunted
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FULL METAL CROWN Features & Functions
Functional cusp bevel
Seating groove
Planar occlusal reduction
Axial Reduction
Structural durability Structural durability
Retention and resistance
Retention and resistance
FULL METAL CROWN Clinical Mandibular Full Veneer Crown