Porcelain and its applications

www.indiandentalacademy.com

PORCELAIN ITS APPLICATIONS AND ITS

INNOVATIONS

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com


CONTENTS:

1. introduction2. indications 3. contra indications4. fabrication of porcelain5. conventional method6. internal characterization7. glazing and surface characterization8. different systems and their method of porcelain

build up9. recent advances in porcelain10. conclusion 11. references


Denture teeth &

Dentures -Duchateau 1774Ceramic paintings and Vases


1887 – CH. Land (platinum foil technique)

1962 PFM – Weinstein

1965 McLean and Hughes aluminium core porcelain

1957 Vines and Sommelman – Vaccum firing

1940 with advent of acrylics PJC lost popularity.


1887 – CH. Land gave porcelain jacket crown

1965 - McLean and hughes -aluminous core

porcelain

1980 - In ceram-slip casting, castable ceramics

Latest 1990’s - machinable ceramics(CAD\CAM)

Evolution of all ceramic restorations :


Ceramics in dentistry is a recent phenomenon, the desire for a durable and esthetic material is ancient.

Although metals have many characteristics that make them useful in dentistry they do not look like natural teeth.

In contrast a superb esthetics, translucency, light transmission and biocompatibility result can be achieved with ALL CERAMICS’s.

INTRODUCTION :


The fracture resistance of all-ceramic crown is based on adequate support by the preparation, proper patient selection, strength of crown material and type of luting cement.

Indications include….§ All anterior teeth where esthetics is of prime factor.

Indications :


§ Conservation of tooth structure and maintenance of periodontal health.

§ Lower incisors where space is available.§ Limited use on the premolar teeth where the occlusion

allows some protection for the buccal shearing cusps.


In cases of parafunctional activity of the mandible,e.g. bruxism. Or any deflective malocclusions remaining uncorrected.

Where occlusal clearance after tooth preparation is less than 0.8 mm, e.g. very thin teeth, deep incisal over jets with lingual wear facets.

Insufficient tooth support or where the preparation design causes sudden changes of thickness in the porcelain.

Contra-indications:


Porcelain modeling liquid Paper napkin Glass slab or palette Tissues or gauze squares Two cups of distilled water Glass spatula Serrated instrument Porcelain tweezers or hemostat Ceramist's sable brushes (no. 2,4, and 6) and whipping brush Razor blade or modeling knife Cyanoacrylate resin Colored pencil or felt marker Articulating tape Ceramic-bound stones Flexible thin diamond disk (about 20 mm in diameter)

Armamentarium


Step-by-step Procedure. After the metal sub structure has been oxidized, it must be inspected carefully. An uninterrupted oxide layer should cover the entire surface to be veneered


When selecting the opaque bottle, shake it to mix the powder thoroughly. Then place it on the bench to allow the smaller pigment particles to settle.

Dispense a small amount of powder on a glass slab or palette. Add some modeling liq uid and mix it with the spatula. Metal instru ments should not be used

Moisten the substructure with some of the liquid and pick up a small bead of opaque With the tip. of the brush or spatula. Apply it to the coping, which should be held with the porcelain tweezers.

OPAQUE PORCELAIN


Use light vibration to spread the material thinly and evenly. Excess moisture that comes to the surface can be blotted off with a clean tissue.

Apply a second bead on top of the first and spread it in a similar manner. To minimize the entrapment of air when the two masses met,


Once the veneering surface is covered, add more material to a dry base. Wetting the initial application before adding more porcelain may be necessary.

When the entire veneering surface has been covered, remove any excess material from other surfaces with the side of a slightly moistened brush


After removing any excess porcelain, care fully inspect the inside of the restoration for porcelain particles


Before firing, inspect the opaque application to see that it satisfies the following criteria

1. The entire veneering surface is “evenly covered with a

smooth layer that masks the color of the metal”2. There is “no excess” anywhere on the veneering surface3. There is no “opaque on any external surface” adjacent to

the veneer4. There is no “opaque on the internal aspect” of the

substructure.


If these criteria have been met, the coping is transferred to a sagger tray and placed near the open muffle of the porcelain furnace for several minutes. This allows moisture to evaporate.


After the first firing, remove the work from the muffle and set it aside to cool to room temperature

When the veneer is removed from the furnace, it will appear yellow; however, when it has cooled, the more representative “matte - white” color is apparent. Fixed opaque should have an eggshell appearance


. After firing. check that the opaque applica tion meets the following criteria:

1. Relatively “smooth even layer” masking the color of the

framework2. Eggshell appearance3. “No excess” any external or internal surface of the

restoration (which would prevent it from seating fully on the die)


The use of several porcelains in one restoration is common. Body porcelains with increased opacity may be used where less translucency is required (e.g., gingival area of the pontic, incisal mamelons) to mimic existing anatomic features of adjacent natural teeth.

Body and Incisal Porcelains


Dispense the neck, body, incisal and other powders on a glass slab or palette.

Mix the powders with the recommended liquid or distilled water. The moisture content for these powders should be the same as for opaque porcelain

Wet the previously fired opaque layer with a small amount of the liquid and place bead of neck powder on the cervical portion of the veneering surface


A tissue is held close for removal of excess surface moisture. During the entire buildup procedure the facial surface should not be blotted with tissue because the smaller pigment particles might be removed.


After placing the neck powered and sculpting it build the veneer to anatomic contour with body porcelain.

Use the adjacent and opposing teeth as a guide. Where contact is anticipated between the wet buildup and stone cast, the cast can be coated with a small amount of Cyanoacrylate resin, immediately blown into a thin layer.

This will seal the surface and prevent the absorption of moisture from the buildup


To compensate for the firing shrinkage that results when the particles fuse, slightly overbuild the porcelain.

A typical metal – ceramic anterior crown will shrink 0.6mm at the incisal edge and 0.5mm midfacially

When the body buildup is completed, assess it for proper mesiodistal, faciolingual and incisogingival contour.

make a cut back for more translucent incisal powder.


Apply the incisal powder in the same manner and overbuild the restoration as described for body porcelain

Mark the opposing teeth on the stone cast with a, red or green felt tip marker. These markings will not be absorbed if the cast first has been coated with Cyanoacrylate resin


Only red or green dyes burn off without leaving a residue, should be used for these markings. Blue or black pigments usually contain metal oxides or carbon, which after firing can discolor the porcelain

Moisten the proximal contact areas immediately before removing the completed buildup from the cast

The internal aspect of the coping should be re-inspected


. Place the restoration on a sagger tray close to the open muffle at the drying

temperature recommended by the manufacturer. A drying time of 6 to 10 minutes is usually sufficient

If restoration is fired prematurely the residual moisture in the buildup may generate steam, and the accompanying Vapour pressure will cause the buildup to explode.

When the bake is completed, the work should cool to room temperature before further handling


cooling rates may lead to residual stresses that will eventually result in porcelain fracture during function

Be especially critical when evaluating the first bake. If the surface is fissured, grind the porcelain before adding any more.

The shape of the restoration should conform to the standards set by dental anatomy and the predetermined occlusal scheme for the patient


Remove all excess material with ceramic bound stones.

A flexible diamond disk is imperative for proper shaping of the embrasure spaces.

To extend its life, the disk should be kept moist When the restoration has been contoured and all necessary

areas reduced, certain portions will probably require a second application of porcelain

Before second corrective bake, clean the restoration ultrasonically to remove any grinding debris


Place the second body and incisal layers correctly on the slightly moistened low bisque bake

However, multiple firing will lead to devitrification of the porcelain, with a loss of translucency and a decrease in the restoration’s fracture resistance


Internal or intrinsic characterization or staining may be accomplished by incorporating colored pigments in the opaque, body, or incisal porcelain powders.

These pigments are ceramic in nature and have physical properties similar to the porcelain powders

If the internal characterization is not achieved properly then the porcelain must be stripped from the substructure

INTERNAL CHARACTERIZATION


The appearance of the finished restoration depends on its color, shade, and characterizing dental porcelain to mimic the appearance of natural teeth

The appearance of restorations can be influenced considerably through the selected use of optical illusion.

The human eye is capable of discerning difference in height and width, but its depth perception is far less developed:.

The perceived size of a tooth depends on the reflection of its line angles and the relative position and spacing of these reflections

CONTOURING


The surface texture of a metal ceramic rest should resemble that of the adjacent teeth, including selected characterizing irregularities that exist on those teeth. Several rules of light reflection must be remembered when attempting to accomplish this

1. A flat surface will reflect primarily parallel bundles 2. A convex surface will result in divergence fleeted light,

whereas a concave surface will create a convergent light bundle

3. Sharp transitions (e.g., geometric line angles) will result in line reflections, but smooth, gentle flowing curved surfaces will create a reflection pattern with greater surface area.


Care must also be taken not to "overcharacterised” which would draw attention to the restoration and reveal that it is artificial.


Metal ceramic restorations are glazed to create a shiny surface similar to that of natural teeth. The glazing cycle can be performed concurrently with any necessary surface characterization

In autoglazing the contoured bisque is raised to its fusion temperature and maintained for a time before cooling. A pyroplastic surface flow occurs, and a vitreous layer or surface glaze is formed.

GLAZING AND SURFACE CHARACTERIZATION


Characterization & Glazing :


Glazing:

Apply the glaze material in the usual manner using a brush. Make sure not to apply the glaze material either too thick or too thin layers.


Finished FPD:palatal view


By contrast in overglazing a separate mix of powder liquid is applied to the surface of a shaped restoration, and the restoration is subsequently fired. The firing procedure is similar to that for autoglazing,


Surface stains are highly pigmented glazes which can be mixed with glycerin and water

When it turns white and chalky, any excess that may have been accidentally applied to the metal surface is removed, .and the restoration is fired

EXTERNAL CHARACTERIZATION


Staining & characterization:

Before starting the staining procedure, make sure the restoration is free of dirt and grease. A roughened surface is favorable.


Apply the stains as thinly as possible, avoid pooling and too thick layers.


Many patients object to the grayness at the margin associated with metal-ceramic restorations. How ever, hiding the margin subgingivally may not be possible. If esthetics is of prime importance, a collarless metal-ceramic crown should be considered.

PORCELAIN LABIAL MARGINS


The collarless crown's most obvious advantage is the esthetic improvement it offers compared to the conventional metal-ceramic restoration

Plaque removal also is easier when gingival tissues are in contact with vacuum-fired glazed porcelain than when they are contacting highly polished gold.

. Therefore, porcelain would appear to be the material of choice for restorations that will be in contact with gingival tissues

ADVANTAGES AND DISADVANTAGES


Due to careless handling, fracture of the unsupported margin is sometimes a problem during try-in or cementation

In addition, the collarless metal-ceramic restoration is more time consuming and therefore more costly to make


A porcelain labial margin is indicated when a conventional metal-ceramic restoration will not create the desired esthetic result

It is contraindication when an extremely smooth,1 mm-wide shoulder cannot be prepared in the area of the ceramic veneer.

the limitations of the operator and technical auxiliaries should be carefully and objectively assessed before the dentist and patient submit themselves to a fixed prosthesis consisting multiple collarless retainers

INDICATIONS AND CONTRAINDICATIONS


Platinum foil matrix Technique: Step-by-step procedure 1.Wax the metal substructure and cast it in the

conventional manner. 2.To prevent the foil from becoming distorted on removal,

block out undercuts apical to the margin. Modeling compound is suitable for the shoulder of this step.

FRAMEWORK DESIGN for LABIAL MARGIN


3.Burnish a small piece of platinum foil onto the facial portion of the die where the porcelain margin is to be placed, and extend it a few millimeters onto the axial wall of the preparation.

4. After burnishing, trim it so there is a 2-to3-mn “skirt” lying cervical to the margin


Remove the casting from the die, together with the foil, and position the assembly between the electrodes of an orthodontic spot welder.

The foil can now be welded to the framework, which should be done as close as possible to the edge of the metal. Four or five welds are usually adequate to attach the foil to the substructure.

The restoration is then fabricated in a conventional manner,


7. When the coronal portion has been shaped to a satisfactory contour, burnish the foil and fill in the ditched portion with cervical porcelain.

8. When the desired contour has been obtained after firing, time the platinum skirt.

9. Leave the platinum that covers the shoulder portion of the preparation and seat the crown on the original die for final cervical contouring


10. When satisfied with characterization, staining, and glazing, remove the foil and cement the restoration after verifying the fit one more time.


Because this technique is less time consuming and easier to perform then the platinum foil technique, it is more widely used.

The substructure is fabricated in the same manner, but the die is coated with a layer of Cyanoacrylate resin, and the porcelain is condensed directly onto it Separation is achieved with a porcelain release agent

DIRECT LIFT (CYANOACRYLATE) TECHNIQUE: -


The principal difficulty associated with the Cyanoacrylate technique occurs during the staining and glazing firing.

because the porcelain is not supported as in the platinum foil technique , the margin tends to round off slightly; therefore ,special shoulder powders are needed.


Step-by-step procedure: 1.Apply Cyanoacrylate resin to the labial margin area of the

die. This acts as a sealant of the porous stone. Compressed air should be used to minimize the thickness of the film.

2. Apply porcelain release agent to the shoulder of the prepared die.

3.Seat the opaqued casting on the die.


4. Mix shoulder porcelain and apply it directly to die and the opaque porcelain.

5. After the first firing of the shoulder porcelain ,reseat the crown on the die.

At this time, the restoration should examined for margin discrepancies.


6. Reduplicate the die, reseat the crown, and apply a thinner mix of shoulder powder to the margin

7. When the firing is completed, use a water-soluble marking agent to detect premature contacts.

The marking agent is applied to the shoulder, and the restoration is then gently tried on the die.

The markings will be visible on the porcelain and the inner aspect of the casting.


8. Adjust any areas of contact of the restoration and proceed with the conventional buildup of body and incisal porcelains, followed by glazing of the final restoration.


Step-by step procedure:

1. After coating the substructure with opaque porcelain, lubricate the die with a porcelain release agent.

2. Apply the porcelain- wax mixture to the cervical shoulder . use an electric waxing instrument to flow it into the proper areas.

3. with a conventional wax-carving instrument, shape the material and blend it into the opaque

PORCELAIN WAX TECHNIQUE:


4.A second application will be needed. Using the electric waxing instrument, keep the mixture liquid long enough so that capillary action can draw it into the marginal discrepancies

The restoration is completed in the conventional manner.


The high strength ceramic core was first introduced to dentistry by Mclean and Hughes in 1965. they advocated using aluminous porcelain, which is composed of aluminum oxide (alumina) crystals dispersed in a glassy matrix

The technique devised by Mclean used an opaque inner core containing 50% by weight alumina for high strength

ALUMINOUS CORE CERAMICS:


High strength core frameworks for all ceramic restorations can be produced with a slip casting procedure such as the In-cream.

Slip casting is a traditional technique in the ceramic industry and is used to make sanitary ware

The starting media in slip-casting is a slip that is an aqueous suspension of fine alumina in water with dispersing agents.

The slip is applied on to a porous refractory die, which absorbs the water from the slip and leads to the condensation of the slip on the die. The piece is then fired at high temperature(11500 C).

SLIP CAST CERAMICS


Weigh out exactly 38 g of VITA In-Ceram alumina powder.


Start to apply the slip in the area of the pontic.

Build up to half of the height of the pontic. Then coat the abutment dies fully and

connect them to the pontic.


! Proceed rapidly when building up the remaining slip.

! Do not interrupt this process, so that drying out of layers that have already been built up is prevented (onion-skin effect).


Carefully expose the preparation margin with a scalpel until the marking can be seen.


Sintering firing:


1965 Mc lean and Hughes

40 t0 50 wt% of Al2O3

Flexural strength 131 Mpa

Platinum foil technique

ALUMINOUS CORE PORCELAIN

Finished CoresMaster model with

diesPlatinum foil adapted to

die

(Hi-Ceram)


Unsintered CrownsDentin Ceramic additions

Finished Crowns on dies

Post-Cementation


Al2O3 slip Glass infiltration

Vita Inceramat3

Giordono 1995 : Al2O3 Core glass infiltrated Ceramic > Strength than Hi-Ceram, Di-Cor & Feldspathic Porcelain

Vaccumat 4000 Premium


Duplication In-Ceram

refractory dies

In-Ceram application

Al2O3 slip vita inceramat

Working model

Glass infiltration 4hrs

11000C

Shrinkage of dies


Application of body and incisal porcelain

Postoperative veiw of In-Ceram

crowns

Finished In-Ceram copings (Air abraded)

Finished crowns

Preoperative veiw

Probster et al : Strength of In-Ceram > IPS Empress < PFM


Fabrication Procedure : 1. Duplicate the working die with an elastomeric

impression material and pour it with the special refractory die material

2. Mix the appropriate shade of alumina slip with ultrasonic agitation, place the mixture under a vacuum,

brush apply it to the-plaster die and shape it with a blade, trimming back to the margins carefully


3. The slip is fired in a special furnace initially through a prolonged drying cycle to 120°. C (248° F) that dries the die material, which shrinks away from the core.

Then the alumina is fired at 1120° C (2048° F) the resulting core is porous and weak at this stage but can be carefully transferred to the master die after the die spacer is removed.

The relatively low sintering shrinkage (about 0.3%) is compensated for by an expansion of the refractory material.


4. Paint a thick coat of the appropriate shade of glass mixture on to the surface of the core and fire at 1100°C (2012°F) As the glass melts.

5. Remove excess glass from the core by grinding and airborne particle abrasion.

Body and incisal porcelain is applied to the core in manner similar to that for metal ceramic crowns.

6. After moistening the core, mix the powder with modeling liquid and apply increments with a brush.


7. Remove moisture with a paper tissue held against lingual surface. The capillary action will condense the porcelain particles slight vibration brings further moisture to the surface before the next increment is added. To prevent voids from forming between increments always add to a moist surface.

8. When the crown has the correct shape cut it back to allow room for incisal porcelain


9. Apply incisal porcelain, overbuilding the incisal edge by 1 to 1.5 mm to allow for firing shrinkage.

10. Lightly condense the buildup with a large whipping brush. Absorb excess moisture with a tissue.

11. Remove the crown from the working cast and add material inter approximately to allow for shrinkage.

12. Dry the crown and fire it.


Leucite based: Hot pressed ceramics are becoming increasingly popular in

dentistry. The restorations are waxed, invested, and pressed in

Most hot pressed materials contain leucite as major crystalline phase, dispersed in a glassy matrix

HOT PRESSED CERAMICS:


Empress 2 ingots


The ingot support and the aluminum oxide plunger is placed in the cold furnace.


Pressing:


After selecting the exact press parameters, Place the investment ring with the ingot, in the press furnace and start the process by closing the head.


The press cycle runs automatically. A beep sound indicates the end of the press cycle.


Mark the length of the plunger on the cooled investment ring.


Separate the investment ring using a separating disc. This predetermined breaking point enables reliable separation of the ingot and the ceramic material.


Break the investment ring at the predetermined breaking point using a plaster knife.


For fine divestment, only 2 bar (30 psi) pressure is applied.


LEUCITE REINFORCED IPS EMPRESS

Pre cerammed Ingots

Processing :


Wax pattern

Ceramic ingot & Al plunger

Investing

Pressing under vaccum 11500C

Sprue removal

Burn out 8500 C

26 min hold


The crystal size varies from 3 to 10 nm and the leucite content varies from about 50% by volume depending on the material

Ceramic ingots are pressed at high temperature from 9000 C to 11650 C [16500 F to 21300 F] depending on the material into a refractor mold made by the lost-wax technique.


Two finishing techniques can be used: a characterization technique (surface stain only) and a layering technique, involving the application of a veneering porcelain

the currently available leucite-containing materials for pressing are IPS Empress, optimal Pressable ceramic and two lower fusing materials, Cerpress and Finesse.


Lithium Silicate based. IPS Empress 2 is recently introduced hot-pressed ceramic. The major crysta1line phase of the core material is a

lithium disilicate. The material is pressed at 9200 C (1690 F) and layered with a glass containing some dispersed apatite crystals.

application for anterior three unit fixed partial dentures.


1. Wax the restoration to final contour, sprue, and. 2. Heat the investment to 8000 C to burn out the wax

pattern. 3. Insert a ceramic ingot of the approximate shade and

alumina plunger in the special pressing furnace. 4. After heating to 11500 C, the softened ceramic is slowly

pressed into the mold under vacuum


5. After pressing recover the restoration from the investment by airborne particle abrasion, remove the Sprue , and refit it to the die.

Esthetics can be enhanced by applying an enamel layer of matching porcelain or by adding surface characterization. The procedure for an FPD is similar.


The evolution of CAD /CAM systems for the production of

machined inlays, onlays, veeners crowns led to the development of a new generation of ceramics that are machinable.

MACHINED CERAMICS


CEREC SYSTEMS PROCERA SYSTEMCELAY SYSTEM


CEREC SYSTEMS

Materials involved :

Vita mart II, Dicor MGC and Pro Cad

Sanidine KAlSi3O8

Mica crystals 70%

Leucite containing ceramic

CERamic REConstruction,

Optical scanning


Optical impression:


The compact, mobile unit consists of three components: a small camera, a computer screen and a three – axis – of – rotation milling machine.


The cad/cam cerec system has evolved from the: cerec-1,which fabricated only marginally fitting single and dual surface ceramic inlays.

Cerec-2,which showed advances in computing, upgraded software and expanded form of grinding technique.


Cerec-3 that can design well-fitting inlays, onlays, crowns, veneers etc., in a single visit.


3D cerec

Scanning and designing

3 dimensional viewing Milling


CEREC In-LAB:


The Alumina Blanks:


The Zirconia Blanks: referred to as “ceramic steel”.


The Spinell Blanks:


Parallel milling with two tools:


High speed milling of copings and bridge frame work.


Completed bridge framework


Cerec system. The cerec system has been marketed for several years with the improved cerec 2 system introduced in the mid- 1990s.


Fabrication procedure: 1.Tooth preparation follows typical all ceramic guidelines. 2.Coat the preparation with opaque powder 3. Image the preparation with the optical scanner, aligning

the camera with the path of insertion of the restoration When the best view is obtained,

it is stored in the computer. 4. Identify and mark the margins and contours on the

computer screen. computer software assists with this step


5. Insert the appropriate shade of ceramic block in the milling machine. The fabrication time for a crown is about 20 minutes . Additional characterization is achieved with stains.

6. Try the restoration back in the mouth, etch, and, lute it to place as described.


The Celay system uses a “copy milling” technique to manufacture ceramic inlays or onlays.

This material is similar to Vita Mark ll. ceramic, used with the Cerec 2 system. Alternatively, blanks of the InCeram Alumina or InCeram Spinell materials can be used. Marginal accuracy seems to be good, a little better than the Cerec 2 system.

Celay System :


CELAY SYSTEM

Uses copy milling technique

Resin pattern fabricated directly on master die and pattern is used for milling porcelain restorations

Jacot et al 1998 : in ceram blanks in celay system.

Inlay pattern mounted (copy side)

Copy milling pattern out of ceramic material

(milling side)


The Pro cera AllCeram system involves an industrial CAD/ CAM processes.

The die is mechanically scanned by the technician, and the data are sent to a work station where an enlarged die is milled using a computer-controlled milling machine.

This enlarge ment is necessary to compensate for the sintering shrinkage

Procera AllCraeam System :


PROCERA SYSTEM

Dies are enlarged to compensate for sintering shrinkage.

Scanning

Milling machine

Shape on computer screen

Contact scanner


Processing method

Procera restorations


Step by step procedure : 1. Tooth preparation follows all ceramic guidelines. 2. The cast is made in the conventional way but the die is

ditched to make the margin easier to identify during scanning

3. The die is mapped using a contact scanner 4. The shape of the prepared tooth is transferred to the

computer screen


5. The design of the restoration is transferred to the manufacturer via computer line

6. The production process starts with milling an enlarged die to compensate for the sintering shrinkage

7. An enlarged high-alumina coping is milled that shrinks to the desired shape after sintering

8. The coping is returned to the laboratory and body and incisal porcelains are applied in the conventional manner


In the captek system the coping is produced from two metal-impregnated wax sheets that are adapted to a die and fried. The first sheet forms a porous gold platinum palladium layer that is impregnated with 97% gold.

Advantages of the system include excellent esthetics and marginal adaptation.

METAL REINFORCED SYSTEMS


Fabrication Procedure 1. Duplicate the working die in the special refractory

material. 2. Cut a piece of the gold platinum palladium impregnated

wax sheet 3. Adapt the foil to the die. Then it is fired to 107C (1965 F)

forming a porous metal coping. 4. Adapt the second gold impregnated wax and refire,

Capillary action draws the gold into the porous gold platinum palladium structure to form the finished coping


Build up the opaque body and incisal porcelains in manner similar to that for a conventional metal ceramic crown.

Glaze the completed restoration and polish the metal foil at the margin. The procedure has been adapted for FPD’s.


Electroformed : The Helioform HF 600 system uses an electroforming

technique to produce a thin Pure gold coping. .


(HELIO FORM HF 600 SYSTEM)

Equipment Polyurethane dies

Completed restorations

ELECTRO FORMED


Step by step procedure 1. Duplicate the working die with the poly urethane

material 2. Drill the polyurethane and glue the electrode into the die 3. Apply an even coat of the silver spacer to the

preparation and allow it to dry 4. Insert the dies into the plating equipment. A magnetic

stirrer ensures circulation of the cyanide free gold sulfite solution


5. Turn on the electrical current, and gold will be deposited on the die at an appropriate rate of 0.02mm per hour.

6. Remove the plated copings by heating the dies and remove the silver spacer with nitric acid or air abrasion.

7. Trim flash from the margin with an abrasive silicone wheel and seat the coping on the die

8. Air-abrade the surface and apply the special bonding paste before porcelain application


Porcelain labial veneers can be fabricated using a refractory die technique as well as on a platinum matrix

PORCELAIN LABIAL VENEER


Ceramic veneer F P D

Ceramic inlay\ metal reinforced F P D

Ceramic veneer / Composite substructure F P D


Step-by-step Procedure : 1. Modify the working die by blocking" out tooth undercuts

with modeling plastic 2. Adapt the platinum foil (0.025 mm). Careful adaptation is

essential for good fit, especially at the proximal incisal margin, where the tinner's joint is made.


3. Remove, clean, and degas the foil. Air borne particle abrasion can be used for this step. Porcelain labial veneers can also be made with hot pressed ceramics and the machinable systems.

4. Build up and fire the veneers. This is generally done in two or three layers, particularly if the veneer is required to mask tetracycline staining and a more opaque initial layer is applied.


5. Contour and glaze the facings..

6. Remove the foil before try-in


1. Pour an elastomeric impression of the prepared teeth in Type IV or V stone;

then repour it or duplicate it in ceramic refractory, 2. Trim the refractory cast as far as possible to minimize the

quantity of ammonia released during decontamination. 3. Mark the margins lightly with a special pencil . Decontaminate the cast by firing according to the

manufacturer's instructions

INLAYS AND ONLAYS


5. Allow the cast to. cool and then soak it in soaking liquid or distilled water for 5 minutes. This will seal the die and prevent moisture from being drawn out of the porcelain buildup:

6. Apply an initial layer of porcelain to the die and fire


7. Build up the restorations onto moist dies; for inlays, leave short of the margins.

8. Make a relieving cut through the central fossa and fire the porcelain

9. Fill in the central fossa area and build up to the margins and

10 Contour and refine occlusion and proximal contacts. Glaze according to the.

11. Remove the investment. Transfer the restorations to the master dies on the mounted cast


The performance of all ceramics restoration has been enhanced by the use of resin bonding. This technique was first devised for the porcelain laminate veneer technique and has been applied to other ceramic restorations.

The technique uses hydrofluoric acid or a less toxic substitute to etch the ceramic and a silane coupling agent to bond a resin Luting agent to the ceramic.

The Luting agent is bonded to enamel later etching with phosphoric acid as with resin retained FPDs and bonded to dentine with a dentine bonding agent

RESIN BONDED CERAMICS


All ceramic Resin bonded fixed partial dentures

Introduced 1986-1988 Ibsen et al and Garber et al

Matthias kern 2005 :Cantilever all-ceramic resin bonded FPD


1. Support the restoration in soft wax with the fitting surface uppermost.

2. Apply a 1-mm coat of the etching gel to the fitting surface only.

3. The etching time will depend on the ceramic material. Feldspathic porcelain is typically etched for 5 minutes.

4. Very carefully rinse away the gel under running water. 5. Continue to rinse until all the gel color has been

removed.

ETCHING AND SILANATING THE RESTORATION


6. Dry the ceramic with oil-free air 7. Apply the silane according to the manufacturer's

recommendations. and care must be taken to clean the fitting face thoroughly with alcohol before cementation,


RECENT ADVANCEMENTS


1993 Luthy et al – Post made of TZP-ZrO2

High flexural strength 1400 Mpa

1994 Sandhaus – Zirconia post with composite core

1995 Akagawa et al - Castable ceramic attached to zirconia post

1997 Ivoclar – introduced Ceramic core directly pressed onto Zirconia post

Direct methodIndirect method


RECENT APPLICATIONS OF CERAMICS IN SURGERY

Recently, the world of surgery is amazed with a sensation : Atraumatic scalpels made of ceramics.

The cutting edge cannot be made thinner than 0.7 microns when metal is used.

Ceramics made up of zirconium dioxide nano-powder with admixtures of aluminum and yttrium in water, can serve to form such a material which can be used to produce the cutting edge thickness of 0.1 - 0.2 microns.

The post operative wound heals up 2 -3 times quicker if the ceramic scalpel is used, as the blades had dissected the tissue without traumatizing it.

(Mendeleev University of Chemical Technology, Moscow, 14/03/2003)


Ceramics in Orthodontics Most recent application of ceramics in orthodontics

is in fabrication of orthodontic brackets. The development and demand for these items has

been driven solely by esthetics. Polycrystalline alumina is the material of choice in

this application. Advantages:: A profitable alternative to metal brackets. Bonds and debonds like metal. Excellent control of tooth movement. Less friction for better treatment times. Lowest profile in an all-ceramic bracket. Maximum patient comfort.


Implants and ceramics: Entering the New

Millennium. The demand for optimal single tooth implant esthetics

has lead to perhaps the most exciting development in implant abutment design, the ceramic abutment.

Three different designs are currently available: CerAdapt. CeraOne. CeraBase.

(The Intl Journal of Oral & Maxillofacial Implants 2000; vol 15; Pg 76-94)


CONCLUSION Improved materials and the bonded ceramic

technique have renewed interest in all ceramic restorations.

The highest strength materials may be suitable for high stress applications including FPDs

However they are relatively new and still lack the support of long-term clinical experience and research


Each system has its own merits, but may also have shortcomings.

Combinations of materials and techniques are beginning to emerge which aim to exploit the best features of each.

Glass-ceramic and glass-infiltrated alumina blocks for CAD-CAM restoration production are examples of these and it is anticipated that this trend is likely to continue….


One who works with his hands is a labourer


One who works with his hands & mind is a craftsman


One who works with his hands , mind & heart is an artist


Bibliography: Kennth.J.Anusavice. Science of dental materials;

10th edition, Kennth.J.Anusavice. Tylmans theory and practice of fixed

prosthodontics. Fundamentals of fixed prosthodontics: third edition,

Prof Herbert T Shillinburg. Restorative dental materials, 10th edition; Craig CG. Applied dental materials; 8th edition, John F McCabe

and Angus W G Walls. Stephen F Rosenstiel; Contemporary Fixed

Prosthodontics Herbert T Shillinburg; Fundamentals of Tooth

Preparations


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Porcelain and its applications

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