Fatima shams dental mat. Lec 7 Hussain aljemaie

This lecture is going to be about dental ceramics. You are going to find extra information from different sources; article and internet just to clarify certain points. However, you need to study from the article. We are sorry , you'll find few seconds from the record where we could not catch some scientific names. But, as we know , our source is the article not the

sheet. Enjooooy reading

Net : Dental porcelain (also known as dental ceramic) is a porcelain used by a dental technician to create biocompatible lifelike dental restorations, such as crowns, bridges, and veneers, for the patient.

The word “ceramic” is derived from the Greek word “keramos” that translates to mean, “burnt earth.” It came from the ancient art of fabricating pottery where mostly clay was fired to form a

hard, brittle object.

The use of ceramics are encouraged by their biocompatibility, aesthetics, durability andeasier customization. The specialty of ceramic teeth is the ability to mimic the natural toothin colour and translucency along with strength. Ceramics have excellent intraoral stabilityand wear resistance adding to their durability.

What are the domestic uses of ceramics?

- Kitchens , bathrooms (mostly found in white color),plates, files … etc.

))nowadays, 95% of crowns are metaloceramics and All ceramics((

History of ceramics and how we came up with idea of using it in dentistry

ceramics ( earthenware or stoneware or tableware) were not familiar to people worldwide back in 1500 , only it was found in china. Until 1570, it became known to people .

- George Washington did not have this new technology ( material ) :( , his teeth ( crowns) were made from hippocampus ( al 3aaj) , and they rot easily , so he had to soak them in red wine at night to be sterilized. George suffered a lot in his life, one of the main reasons were because of his

teeth .

Europe (1570 ) started to make tableware, plates and domestic porcelain. So after that it was familiar world wide. Martho polo described ceramics to people and said the following :

A ceramic so white that it was comparable only to snow,so strong that vessels needed walls only 2–3 mm thickand consequently light could shine through it. So continuouswas the internal structure that a dish, if lightlystruck would ring like a bell.

So people back then were motivated to use ceramics in arts, clay and domestic uses as we said .

Then we started using this material in dentistry :

= French apothecary named Alexis Duchateau constructed teeth made with porcelain for dentures , however he faced difficulties : - teeth did not bind to the beneath material (base ), brittle and produced annoying sounds when the pt worn the denture.

=then Fonzi started to use porcelain for natural teeth.

Fatima shams dental mat. Lec 7 Hussain aljemaie

=(cherzland (was the first person who talked about feldspathic porcelain, during 20 century , using porcelain to make teeth (1905-1950) , because they were brittle they used to fracture a lot . they had to use them to avoid dental attrition .

During that period (1950) , 2nd world war, polymethane methyl acrylate was used in

الطيارة ( قيادة ) windowsقمرة

They discovered that airplane when the fall down , windows which are made of this material break and enter into captain's body and doesn't make any reactions so it is not harmful to the human body. For that reason, this material was used to make polymethane methyl acrylate teeth or acrylate teeth. However acrylic teeth after using them they noticed high discoloration.

Then they started to use composite.

In America (50's), started to use porcelain supported by metal, but there was a problem, coefficient of thermal expansion was different which caused debonding or devariarion

Until Weinstein

came at the end of 50s and corrected the composition of feldspathic porcelain (later we will talk about it more in details). He corrected rough material called lucide

In 50s , Coefficient of thermal expansion of porcelain and metals became close to each other) , so porcelain fused to metal crowns were stable and stayed for long periods for (20, 25, 30 years ) and failure was not because of mechanical factors like the separation of porcelain from metal. It's usually iatrogenic which leads to 2ry carries . so most of PFM crown failure is due to : - 2ry carries - periodontal disease . NOT because of disintegration b/w porcelain and metal (mechanical failure). This step was on the best that developed dentistry.

Price of gold was more expensive in 70s because king Faisal cut off oil from America and European countries for more than 40 days , and this is why they stopped making porcelain fused to gold .Then, they started using (porcelain fused to other materials like PFM and had more failures.

In 60s-70s porcelain fused to Alumina which increased the strength, but aesthetic properties and appearance was lower not better.

In 80s , instead of making crowns in labs, machine was invented - expensive and not found in Jordan, only in certain countries- that can make crowns in 30 minutes ( in

5th year we are going to be given an overview about it) .

So they tried to remove the metal because as we know it is a ( very rough material) and will not give line structure that we want and for that reason , string was used which was

nice and opaque and we can start with ((.

Fatima shams dental mat. Lec 7 Hussain aljemaie

Michal – French with Moroccan origins- started to talk about Alumina crowns. He got the idea from (al tanoor ovens ) from our countries .

و ( ) يسخنونه و يخلطونهم بنتلفظ هيك اعتقد ما على قش مع طين عن عباره التنور فرنثابت . و ناشف يصير و الطين يظل

So he did the same, brought alumina structure, heated it for 8 hrs , and voids were produced , filled them with glass material , eventually came up with a material that was called Incerams back then. It was nice, however it took hours to produce it, was expensive and not always gave the wanted results.

In 2000, 90% of All ceramics were Zarconia based.

In 2002, Alumina zarconia ceram composite and lithium disilicate ( we will talk about them in details later).

هل ( : سألت نفس in-ceramطالبه ؟ ) alumina crowns ههو

)Dr answered : yes, Alumina based crowns and zarconia based crowns and they have the same technique which is called slip cast and we are going to talk about it later(

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In general, ceramics that we use are either in vigorous form (glassy ceramics) or crystal form (crystal ceramic).

In the crystal form , arrangement of atoms is the same, which allows light to pass through it easily (To understand more, in crystalline matrix, light goes to atoms or into atomic spaces) and no deflection of light happens like what happens in the natural tooth surface. This order of atoms gives more strength but aesthetics becomes lower not like the tooth structure.

In glassy matrix (form), we have different order of atoms similar to tooth structure. Strength is lower because bonding in not 100%. However, this order gives us deflection ( we can get deflection index that can be modified to make it same as our tooth structure and that will increase aesthetics .

So, glassy ceramics are better than crystalline ceramics. Whenever we increase the crystalline phase, aesthetic properties decreases. On the other hand, when glassy phase increases, we are definitely going to get better aesthetic properties closer to natural tooth but it will be weaker.

Net : Ceramics can be very translucent to very opaque. In general, the more glassy the microstructure (i.e. noncrystalline) the more translucent it will appear, and the more

crystalline, the more opaque .

What are the components of dental porcelain?

)1(Vigorous silica : will give glassy matrix. (20-50%))2(Modified mullite coat: prevent silica to get back to crystalline phase.

)3(Feldspar : based on sodium ( in dental porcelain is more than 70% but in demostic porcelain not more than 10%)

Fatima shams dental mat. Lec 7 Hussain aljemaie

)4(Kaolin ( in dental porcelain 0-3%))5(Quartz

)6(Nitphormic oxides (especially Aluminum Oxides): increase strength )7(Other components that give us radio-opacity: to be detected and seen in

radiographs.

Check for % of these materials from the article.

All these precise percentages allow us to get the resultant material and heat it in oven with 900 c.But when we have silica alone we need more than 2000c.

(Dr showed two pictures )which one is quartz and which one is feldspar )feldspar in feldspathic porcelain(?

One of them is translucent .

We do not need to cast or sinter silica but sometimes in titanium we need high tempreture so not easy to cast

Article:

COMPOSITION OFDENTAL PORCELAIN Table 3.4.1 Composition of the earliest dental porcelains were mixtures of kaolin,feldspar and quartz, and were quite different for earthenware,stoneware and domestic porcelain, as indicatedin Figure 3.4.2. It was not until 1838 that EliasWildman produced dental porcelain with the translucencyand shades that reasonably matched those ofthe natural teeth. The compositions for domestic anddental porcelain are shown in Table 3.4.1.

Kaolin is a hydrated aluminium silicate(Al2O.2SiO2.2H2O) and acts as a binder, increasing theability to mould the unfired porcelain. It is opaque,however, and when present, even in very small quantities,it meant that the earliest dental porcelains lacked adequate translucency. Thus, for dental porcelains thekaolin was omitted and could therefore be consideredto be a feldspathic glass with crystalline inclusions ofsilica.

The quartz remains unchanged during the firingprocess and acts as a strengthening agent. It is presentas a fine crystalline dispersion throughout the glassyphase that is produced by the melting of the feldspar.The feldspar fuses when it melts, forming a glass

Fatima shams dental mat. Lec 7 Hussain aljemaie

matrix.

The feldspars are mixtures of potassium aluminosilicate(K2O.Al2O3.6SiO2) and sodium aluminosilicate,also known as albite (Na2O.Al2O3.6SiO2).Feldspars are naturally occurring substances, so theratio between the potash (K2O) and the soda (Na2O)will vary somewhat. This affects the properties of thefeldspar, in that the soda tends to lower the fusiontemperature and the potash increases the viscosity ofthe molten glass.

As we said in ceramics we either have:

1-More glass which is more aesthetic 2-More crystals which is more strong

3-And there is another type between them ( 22:28- 22:30) (means crystal filled with glass).

We will go through them with more details

Whenever we want more aesthetics, then we are talking about lidomeric glass material , ( 22:22-22:32)when we want more strength , then we are talking about polymeric crystal material ( 22:46)this gives us wide spectrum of (22:55) ceramics.

Porcelain laminated material ( porcelain laminate veneers)

which is know as Hollywood smile. We call it like this , because first people who could afford it were Hollywood celebrities-:

External portion (for aesthetic) : feldspathic porcelain which mostly glass or hotpress ceramic( 23:30) like lithium disilicate

Internal portion (for strength ): can be made of lithium disilicate, or (22:38) alumina or ( 22:38) zarconia.

)) porcelain centered zarconia or alumina are Incerams and not used these days, so we are not going to focus on them in this lecture((

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Hussain aljumeai ( 24: 00 )

Things that we can do with feldspathic porcelain: 1 (porcalin laminate veneer.

2 (veneer. (laminate veneer alone and bonded to tooth structure because its weak -so it must reinforced- but has a high easthetic property. We can do acid-etch as we said there are etchable and non-etchable ceramics)

Fatima shams dental mat. Lec 7 Hussain aljemaie

So, the feldspathic porcaline is one of the etchable ceramics and as we make bonding to tooth structure, we strengthen the material.

)the bonding with tooth structure will give us the strength and the porcelain itself will give the asthetic.(

One more thing, when we add the luicide to feldspathic porcelain, it becomes bondable with metal. The best porcelain to be bonded with casting alloys is felspathic porcaline(we will talk about casting alloys in the next 2 lectures)Also we can put the feldspathic pocaline above the zerconia an lithium diselicate.

We can use also particles filled glass (dentistry is not far away from industrial environment)- the same principle as the Pirecs elawane elzogagia ele btt7amal dragat 7ararah 3alia.In dentistry, ceram is glass ceramics that tolerate high temperature by heat treatment slowly for 8 hours. The type of crystals present are either 1) glassy phase. 2)dista phase. 3)lempha phase for silica.

We can change and improve that by vetrification and devetrification (H.W)We can also increase the percentage of crystals by heat treatment or decrease it by rapid cooling.

If we make slow heat treatment for the crystals, this will not affect life properties or asthetic properties, but it will increase the strength!

)these materials if proper bonding and cementation are done, they will stay up to 15 years.(

At that time, luicide reinforced was introduced. It is the same glass particles but they add to it luicide. The luicides present in the feldspathic porcaline with metal, they increase the percentage of …………. (min28.30). In lucide reinforced the percentage become 45-50%.

Now, we use the luicide reinforced in veneers and luminars.

The disilicate compress ceramics are the most popular material used for aesthetic purposes (we will talk about it later also about crystalline ceramics (zerconia) and mainly about letrium tetragonal poly crystal zerconia)

These are the main categories that we use them in ceramics (how to make ceramics) -:

1 (selitll: powder mixed with water to become (straby),in the lab we made the casting metal then we mix the porcelain and apply it layer by layer then inserted inside the oven. Then the temperature start to increase and water will start to evaporate, and the porcelain will fuse to metal at the fusion temperature because the metal has oxides and the porcelain has oxides so they will unit together.

Fatima shams dental mat. Lec 7 Hussain aljemaie

2 (cerams: a glass material as we said, heat treated for 8 hours (long procedure) or by pressing or ingection molding –we press the material- or by machining by a machine that mix them.

Properties of dental ceramics-:

1 (full ceramic or glaze ceramics, they are very smooth so they do not accumulate plaque and their smoothness is nearly the same as the tooth.

2 (does not cause adverse reactions from the pulp.3 (color stability more than composite.

4(mechanical properties: they are brittle material, they are much stronger in compression than tension so when we design a cavity we donot put porcelain under tension.

5 (strength depend on many factors: layering – self treatment – the underneath structure – machine ceramics.

6 (Fracture toughness: which is a material specific... Zerconia > alumina >lithium disilicate > feldspathic porcelain.

)pic. In slide (A prepared tooth and 2 layers, there are air bubbles in one of the layers because of (46.26) technique. Because of the presence of air bubbles the fracture will be faster.

Crack propagation: whenever present in the area that has load, catastrophic failure will occur.راح شقوق فيها عملنا لو بس تنمزع ماراح وشديناها ورقه نمزع حاولنا لو مثال،بسهوله !! تنمزع

The main failure of ceramics is fracture, why?

1 (because it is brittle material.2 (because the bonds in ceramic are covalent bonds.

)covalent bonds are fixed, so the material is a stiff material. when they are made, voids and cracks happen. Also, water always affect the material so it becomes weak(

)in metal, the bond is ionic bond always in movement not fixed(

How to make ceramic stronger??or how to prevent the fracture??

1 (We make ceramic and underneath it there must be metal or sufficient tooth structure or zerconia.

2 (Adjust the coefficient of thermal expansion so the bonding properties become better.

Which one must be in a high coefficient and which one must be in a low coefficient metal or ceramics??

3 (disphasial strengthening: when changing the way of the crack, the material will become stronger.

Fatima shams dental mat. Lec 7 Hussain aljemaie

راح نمزعها بالنصوحاولنا كبسه حطينا لو بالورقه، شقوق في يكون لما مثال،عن غير ثانيه نقطه من لو تنمزع من اكبر قوة محتاجه تكون بس طريقها

بسهوله مابتنمزع يعني االتجاه، نفس في انمزعت4 (hydroxide alumina or glass infiltration like the ceramic

5) retreatment like in cerams , solidify crystallization.

One thing that causes fear to us about ceramic is the hardness of the material so it may causes abrasion to the opposing tooth structure because it is hard material.

Zerconia is harder than ceramic so they think it may cause more abrasion to tooth structure but it is not true, it causes less abrasion because it is one phase.

As the crystallization phase increase >>>>>> translucency becomes less.As we increase the glassy phase >>>>>>> translucency increase so aesthetic properties become better .

Thank you and sorry for any mistakes

Done by:Fatima shams Hussain aljemaie

Special thanks to Yaqeen Albahadili and Dr. Mohammed Almousa.

Miracle is another name for Hard work

Fatima shams dental mat. Lec 7 Hussain aljemaie