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ALL CERAMIC RESTORATION
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All ceramic restorations:-
-All ceramic inlays
-all ceramic onlays-porcelain laminate veneers
-all ceramic crowns
Fabrication process:1-sintered
2-heat pressed
3-cast
4-slip cast5-computer generated
6-metal reinforced
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1-Sintering steps:
-mixing slurry powder +liquid -condensation
-vacuum firing -staining and glazing.
Examples
I Aluminous porcelain jacket crowns
-Either1- Use platinum foil (0.5)
-We choose platinum because it is a noble metal doesnt form oxide so no fusion
will occur.
-The foil will cover the stone
-.N.B.porcelain can't be applied on stone die.
-Then build the porcelain core (40-50% alumina) over the foil.-the final contour (restoration) either formed by:
1-porcelain layering technique.
We add porcelain layers using feldespathic porcelain
2-surface characterization, build the core to its maximum contour from the
beginningadd colors to the surface.
-In all-ceramic we dont need opaque coz the color is matched.
2-Refractory die (vitadur-N and Hi-ceramic)
special material smoother than stone die to apply porcelain directly.
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II optec HSP (High Strength Porcelain)
-refractory die (with matching thermal
expansion)-firing at 1038C
III foil crown>>1st system (vita)
>>pt foil(0.09-0.159mm burnished on die)
>>feldspathic porcelain
IV Mirage
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2-Heat-PressedSteps:
-wax pattern
-investment
-burnout at 850C-pressed at 1150C
Injection molding (ingots are softened not melted)
-surface staining or layer technique.
Examples:
I IPS empress 1(ivoclar po rcelain s ystem )-leucite based-inlays,onlays,veneers,crowns
II IPS emp ress 2-Lithium silicate based
-crowns,FPDs
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3-Slip-casting
-Slip: suspension of fine particles in a liquid
-Liquid=alumina powder, water, additive
Steps:
1-duplicate the stone die after coating it with spacer.2-use special die plaster as duplicating material this plaster
-Porousso can absorb water.
-Shrink upon heating.
3-after duplication coat the special die with the slip.4-upn drying water will be absorbed by the porous plaster from
slip (condensation), so layer of slip will be participated.
5-Sintering 10 hours at 1120C (shrinkage of the die)so it will
be separated from the slip shell.
6-Mix of glass powder and water applied on coplings.
7-infiltration 4-6 hours at 1100C (glass infiltration)molten glass
is drawn into the porous by capillary action to reinforce and
strengthens the shell.
8-excess glass removed-finish with air abrasion.
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Examples:
I in-ceram spinell
-Magnesium spinell (MgAl2O4)
I I in-ceram zir conia
-Zirconide (ZrO2)More strong
N.B.-empress and in Ceram are the most usable techniques
-Shoulder finish line is used because it provides both marginal fit
and resist breakage.
-Shoulder with bevel finish line should be avoided because forceswill be directed to the bevel causing fracture.
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4-Cast Glass-ceramics-Gass-ceramics
Steps:
1-Wax pattern
2-Investment
3-Burnout
4-melt the porcelain then cast the glass ceramic with motor driven casting machine (like
metal)
5-glassceramics surface staining or layer technique
*This technique not used any more.
Examples:
I Dicor
-Tetra silicate fluomica
I I Dicor plus
-Dicor core and aluminous porcelain
III Dicor MGC (Mica Glass Ceram ic)
-Higher percent crystallinity-Cerec process
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5-Computer-generated systemsI CAD-CAM
I I CEREC Process
-Laser imaging camera (optical impression) scanning the preparation after coating itwith opaque powder.
-Operator programs the design of inlays/onlays
-Computer directs the milling machine
-Dicor MGC, Vita MarkII
I I I celay process
-Direct resin pattern (tooth-die)fabricated on the prepared tooth or on master die.-Copy milling
I V Procera All-Ceram system-Industrial CAD/CAM process
-Die scanning, contact scanner by touching the dieenlarge it a little so it
will compensate for porcelain shrinkage later during firing.
-Milling machine
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6-METAL REINFORCED SYSTEMS-Thin metal coping on which the ceramic is fired
-It is metal ceramic as opposed to all-ceramic
-provide best marginal accuracy.
I Captek SystemSteps:
1-duplicate working die in the special refractory material.
2 -2 metal impregnated wax sheetsadapted to a die and firedformin
gold-platinum-palladium coping layer
3--Porcelain application in a manner similar to that for a conventional metal
ceramic crown
I I ElectroformedSteps:
1-the working die with the polyurethane material.
2-coat the die silver spacerdry
3-insert the die into the plating equipment.
4-Pure gold coping (controlled thickness)
5 -Noble metal paste primer
6-Porcelain application
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I ndications of al l-ceramics1-High esthetic requirements
2-Favorable distribution of occlusal load (due to the weakness of therestoration).
3-Considerable proximal caries
4-Incisal edge reasonable intact (no attrition)
5-used with endodontic teeth if used with cement mask the metallic color.
Contraindications1-Conservative restoration can be used2-High caries index
3-Insufficient tooth structure
4-thin teeth facial-lingual
5-Unfavorable distribution of occlusal load (patient with Para functional habit)6-endodontic teeth with post and core because: Translu cency o f porcelain
cannot m ask out cast metal or p refabr icated post s ystem.
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Advantages:
1-superior esthetic.2-excellent transulecency(similar to that of natural
tooth)
3-good tissue response.
Disadvantages
1-low strength
2-abrasive
3-marginal accuracy
4technique difficulties
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In-Ceram Impress
Incisally 1.5mm 2mm
All around 1.2-1.5 1mm
Step by step procedure 1-Incisal (occlusal reduction)
The completed reduction of the incisal edge should provide 1.5 to
2 mm of clearance.
2-Facial reduction
orientation grooves placed :one in the middle of the facial wall
,one in the mesiofacial, and one in the distofacial line angles.
1-1.5mm reduction is performed with a cervical component
parallel to the proposed path of withdrawal and an incisalcomponent to the original contour of the tooth.
3-Lingual reduction
1-1.5mm clearance in all mandibular excursive movements has
been obtained4-Shoule finish line is on all surfacesshould be 1-1.2 mm wide.
If the margins are subgingivally the finish line should be deep chamfer.
5-Finishing
amount of reduction
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*Hight of clinical crown for all ceramic crowns5mm before tooth preparation.
For porcelain fused to metal 3.5 mm
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**Problem with fixed bridge all ceramicweak at
connectorthe connector should be at least 4
mmtoo bulkyimpinge on IDPtissue irritation
(contraindication from periodontal view)
***FPD span length:
Anterior to canine not more than 11mm
Distal to canine not more than 9mm
BESTOFLUCK
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