All Ceramic Restoration I

‫املحاضرة التانية و الثالثة ترم تانى‬

Introduction
PFM composed of 2 layers:
 1 set Layer: metal substructure.
 2 nd Layer: covered by ceramic material for esthetic.
Disadvantage of PFM:
 Unesthetic: ‫التكيبة ىالب اف ام نفس‬ ‫مهما كنت شاطر مش هتعرف تخىل ر‬
‫ن‬
‫البورسلي هتمتص الضوء الواقع عليها‬ ‫اللون السنة المجاورة و دا ألن طبقة الميتال اىل تحت‬
‫ن‬
‫السنتي‬ ‫وتخىل فيه فرق نف الفاليو واضح ن‬
‫بي‬
 Appear of metal collar from gingival margin
 Allergic reaction to Nikal in the metal alloy
All ceramic restorations are considered the most esthetically acceptable prosthetic restorations.
Advancements are made recently to overcome disadvantages of this material.
Traditionally ceramic crowns were referred to as “Porcelain Jacket crowns”.
Disadvantages as it is brittle
Ceramic = Glass
We use Zircon as a core for porcelain in all ceramic restoration instead of metal coping as in PFM
All ceramic
Monolithic (unilayer) Bilayer
‫ودا نوع جديد عباة عن طبقة واحدة فيها كل المكونات عشان‬ - Consist of 2 layers (one for core & other for
bilayer‫نتغلب ع مشاكل ال‬ porcelain veneer) so need more reduction
- May have a problem as detachment occur
bn 2 layers
Another classification
A. Microstructure classification
Glass based -aluminosilicate matrix or Feldspathic porcelain “pure glass
“
-excellent translucent “the highest translucent “
-strength only 70 to 90 Mpa
N.B: Strength is inverse proportioned to translucency
Glass based -to defeat the low strength of glass-based material, we put different
with crystalline types of fillers into material
fillers  Leucite = Empress Ceramic “2nd translucent material after
Feldspathic but still low strength (nearly 109 Mpa) “
 Lithium Disilicate = E-max Ceramic (360 Mpa) “gold stander”
 Zirconia + Lithium Disilicate = Suprininity

 Remember that ceramic has a problem of crack & crack propagation, so we

try to solve it by adding filler
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 Polycrystalline -take appearance of crystals instead of being amorphs pattern
-there were 2 types (alumina & zirconia) but alumina not used today as it was hard
in cutting + high opacity
-Zirconia restoration has a flexural or bending strength values of 900 -1200 Mpa
-another advantage for zirconia is transformation toughness:
▪ At first ceramic has a tetragonal phase particle that transform into
monoclinic phase particle to try to stop the
crack from propagation

Hybrid -mix composite with ceramic to take advantage

ceramics of composite “cushion effect “to defeat brittle
disadvantage of ceramic

B. Processing technique classification

1. Sintering -as we know, ceramic supplied as powder & liquid so we make a mix then apply
mix layer by layer on refractory die (special type of stone that has pores in
between, these pores absorb water so the mix harden) “this stage called split
casting”
-one of the disadvantages is porosity as the mix made manual “chance formation
of air bubbles “that affect esthetic (black spots appear on restoration) & weaken
the ceramic

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 -when feldspathic veneers were introduced, they presented 0.5 mm of thickness
& tapered down to practically nothing at the margins.
-we made over contour during applying of layers as there will be shrinkage after
firing

2. Pressing -here ceramic supplied as ingots “‫”ع شكل اسطوانة صغتة كه‬
(Injection -using lost wax technique “ ‫الب اف ام بس هنا هيتحول كله‬
‫انه فيه واكس باترن عادى زى ى‬
molded) ‫”لسياميك‬
‫ر‬
-we put these ingots inside heated investment material then apply pressure to
soften not melt ceramic
-pressed ceramic requires at least 0.75 mm or more of reduction
-another issue with pressed ceramic was their tendency to appear less
transparent & less esthetically pleasing than traditional feldspathic veneers but
better strength
-these new pressed materials tended to appear opaquer & more monochromatic &
required the addition of extra veneering porcelain to match the natural dentition.
-here we can use glass base fillers type

3. Infiltrated -historical, was made by veta company

ceramics -so called Veta in ceram (alumina or zirconia types)
-Zirconia type was better as it has 34% zirconia
- related to hybrid type of ceramic (composite + ceramic)
-same method of sintering but after firing of die with ceramic in ferns, we will add
composite at the outer surface of ceramic (outer surface has micropores after

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 split cast & firing so easily attached to ceramic), now we have both advantage of 2
materials

‫“دلوقب ر‬machine
4. Machined - ‫الشكات وفرت قوالب للكاد كام من كل األنواع اىل اخدناه فوق‬ ‫ر‬ form “
ceramics -depend on CAD/CAM (Computer Aided Designing Computer Aided
Manufacturing)
- first step “scanning”: we do scan by intraoral camera instead of tradition
impression
- -2nd step “designing”: we make the design on computer
-3rd step “milling”: ‫الديزاين بيتم تشكيله ف الجهاز بواسطة حاجات شبه البتات‬
-4th step “hands on experience”: try in on the cast (there some types need
sintering & others don’t need)

All Ceramic Restoration II

‫املحاضرة التالتة ترم تانى‬
Advantage of ceramic
1. Excellent esthetics: Superior esthetics and excellent translucency.
2. Excellent biocompatibility: good tissue response even with subgingival margins (No irritation, no
inflammation, no accumulation of food) ‫اىل باألحمر ده من السنة اىل فاتت‬
3. Slightly more conservative reduction of the facial margins than PFM “need more preparation to
accommodate metal & ceramic “but least conservative at all”.
4. Restore function and give maximum retention "Especially recent types we can use in posterior
restoration including multiple bridges".
5. High color stability and low conductivity.
Disadvantage of ceramic
1. Brittle in nature
2. Poor tensile strength “so week in tension”
3. Difficult in repair
4. Among the least conservative preparations as general “need thickness to give strength as ceramic
has low tensile strength “.
5. Proper preparation design is critical to ensure mechanical success " need thickness minimally 1mm
in ideal finish line & thickness may reduce in non-stress area but this needs skill from dentist &
technician "

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6. Reduced strength compared to ceramo-metal crowns “we overcome it recently by zircon "
7. Wear has been noticed on the functional surfaces of natural teeth that oppose porcelain
restorations " hard than tooth structure "
8. When used as FPD the connector size must be large (4x4) buccolingually & occlusogingivally not to give
space enough to accommodate papillae which might lead to impinging on the interdentally papilla
causing inflammations as ceramic has low tensile strength need thickness if bridge is all ceramic
Guidelines in ceramic restoration
I. Guidelines for ceramic material selection
1- Strength
as we know
✓ Feldspathic porcelain: 70 to 90 Mpa
✓ Empress type: 109 Mpa
✓ E-max: 360 Mpa
✓ Zirconia lithium disilicate reinforced: 480 Mpa
✓ Zircon: 900: 1200 Mpa
Inspite of high number of fracture strength, never use all ceramic
bridge in long saddle “weak in tension”
In 3-unit bridges, we prefer zirconia rather than glass ceramic
Monolithic type is more strength than bilayer type as bilayer has 2
layers (one for hard ceramic & other one veneer of low strength porcelain that easy to be fractured
“week restoration at all”)
2- Bonding ability
❖ Glass ceramic is better in
bonding than Zirconia as
zirconia is crystal & not have
amorphous phase so acid can’t
attack crystals during etching
“poo
❖ Protocol for bonding of glass
ceramic:

❖ In cases of over tapering or short

clinical crown, we use glass ceramic
to take advantage of good bonding
ability ‫دا جدول توضيحى للبروتوكول‬
‫متذكرش ف المحاضرة بس موجود اهو للى‬
........‫مهتم‬

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 3. Translucency
‫ن‬
➢ Translucency ‫ فبالتاىل النوع األقوى "الزركونيا " هو األقل ف‬,‫ تقل‬Translucency ‫زى ما‬
‫عرفنا ان كل اما القوة تزيد كل‬
➢ Glass ceramics is high esthetic than zirconia “poor esthetics “
➢ Bilayer type is better than monolithic in translucency & esthetic
4. hybrid space
❖ Hybrid ceramic is best in conservative preparation (.3 mm) then
glass ceramic then zirconia monolithic & the least conservative
one is Zirconia bilayer

II. Guidelines for patient selection

➢ Don’t use ceramic restoration with patient has harmful habits
such: nail biting, finger or pencils & bruxism or edge to edge
teeth or deep bite as all of them exert harmful stress & tensile stress on
restoration
➢ Tooth with intact (sufficient tooth structure to support the restoration)
particularly in incisal area
➢ Not to exceed a maximum porcelain thickness of 2 mm; otherwise,
failure of brittle material will occur

III. Guidelines for tooth preparation

‫قبل ما نكمل هنتكلم عن اختيار انى نوع مناسب للبريدج‬
▪ Zirconia is the best type acc. To strength but not esthetic so if we will use it posteriorly, use zirconia
monolithic type but if used anteriorly we use bilayer type
The 7 golden rules
▪ Rule 1
o Understand the tooth reduction requirements for each
crown material in order o maximize esthetics & strength
of your restoration
o Ex; for PFM crowns optimal reduction is 1.5 mm allow for:
 0.3 mm space for metal substructure
 0.2 mm for opaque porcelain
 1mm for porcelain for good strength & esthetics
o For feldspathic or lithium disilicate crown, conservative
preparation can be made to maintain proper anatomic
contour
o For monolithic zirconia crowns (0.5 – 1 mm)
preparation can be made to maintain proper anatomic contour
o For bilayered zirconia crowns; most CAD/CAM systems recommend that the minimum axial wall
reduction for anterior anterior crowns can be 1mm to 1.5 mm & 1mm to 2mm for post. Crowns
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▪ Rule 2 “finish line”
 For all ceramic crowns, the finish line is recommended to be a rounded internal
shoulder (use special bur with flat end & has round margin)
 To prevent unfavorable distribution of stresses & minimizes the risk of the
crown fracturing
 Scanners can read shoulder margins with round ends more accurately
▪ Rule 3 “controlled reduction “
By depth cutting bur

▪ Rule 4 “triple angulation for labial surface “

 Make reduction in 3 planes during
preparation of Ant. Teeth in labial
surface
 The reduction should be multi planar
so that uniform reduction is made &
the resulting all ceramic crown gives
natural reflection as light passes
through the facial surface
▪ Rule 5 “roundation & no sharp angles “
 The smoother the surface, the lower the
stresses placed on the porcelain crown which in
turn decrease the potential for fracture
▪ Rule 6 “no undercuts “
 The prep shouldn’t have any undercuts, parallel
walls not a 90-degree shoulder margin
 Should be to 8 degree of tapering “good during scanning “
▪ Rule 7 “respect occlusion “
 Check centric anterior lingual contact
 The occlusal load should be favorable distributed
 In general; centric contact must be in an area where the porcelain is
supported by tooth structure (in the middle third of lingual/palatal
wall)
 If you make restoration out of the contact, over eruption
of opposing will interfere occlusion & fracture the
restoration

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