Department of Prosthodontics TSMU Replacement of defects of teeth and dentition by cast and metal-ceramics prostheses. Indication. Technological characteristics and clinical use

METAL CERAMIC CROWNS

METAL-CERAMIC RESTORATION ALSO CALLED PORCELAIN FUSED TO METAL RESTORATION (PFM). CONSIST OF A CERAMIC LAYER BONDED TO A THIN CAST METAL COPING THAT FITS OVER THE TOOTH PREPARATION.

METAL CERAMIC RESTORATION COMBINES THE STRENGTH AND ACCURATE FIT OF A CAST RESTORATION WITH THE COSMETIC EFFECT OF A CERAMIC CROWN.

METAL-CERMIC RESTORATION WITH THE METAL UNDERSTRUCTURE, METAL-CERAMIC RESTORATIONS HAVE GREATER STRENGTH THAN RESTORATIONS MADE OF CERAMIC ALONE.

METAL-CERMIC RESTORATION CAN BE USED IN A WIDE VARIETY OF SITUATIONS INCLUDING THE REPLACEMENT OF MISSING TEETH WITH FPD’S.

METAL-CERMIC RESTORATION IS A COMBINATION OF METAL AND CERAMIC, THE TOOTH PREPARATION IS ALSO COMBINATION OF DEEP REDUCTION FACIALLY AND SHALLOWER REDUCTION LINGUALLY. THERE MAY BE A WING ON EACH PROXIMAL SURFACE WHERE THE DEEP REDUCTION ENDS AND THE SHALLOWER PROXIMAL REDUCTION BEGINS.

METAL-CERMIC RESTORATION ADEQUATE REDUCTION IS ESSENTIAL FOR ACHIEVING A GOOD ESTHETIC RESULT.

METAL-CERMIC RESTORATION Inadequate space for a sufficient thickness of ceramic material- 1. Poorly contoured restoration affecting both esthetic and health of the surrounding gingiva.

METAL-CERMIC RESTORATION 2.The shade and translucency of the restoration will not match the adjacent natural teeth.

ANTERIOR METAL-CERAMIC CROWNS A UNIFORM REDUCTION OF APPROXIMATELY 1.2MM IS NEEDED OVER THE ENTIRE FACIAL SURFACE.

ANTERIOR METAL-CERAMIC CROWNS TO ACHIEVE ADEQUATE REDUCTION WITHOUT ENCROACHING UPON THE PULP – FACIAL SURFACE PREPARED IN TWO PLANES THAT CORRESPOND ROUGHLY TO THE TWO GEOMETRIC PLANES PRESENT ON THE FACIALSURFACE OF AN UNCUT TOOTH

ANTERIOR METAL-CERAMIC CROWNS FACIAL SURFACE IS PREPARED IN A SINGLE PLANE THAT IS AN EXTENSION OF THE GINGIVAL PLANE – INCISAL EDGE WILL PROTRUDE RESULTING IN BAD SHADE MATCH OR OVERCONTOURED “BLOCK”.

ANTERIOR METAL-CERAMIC CROWNS FACIAL SURFACE PREPARED IN ONE PLANE THAT HAS ADEQUATE FACIAL REDUCTION IN THE INCISAL ASPECT- FACIAL SURFACE OVERTAPERED AND TOO CLOSE TO THE PULP.

ARMAMENTARIUM 1.LAB KNIFE WITH NO:25 BLADE 2.SILICONE PUTTY 3.ROUND – END TAPERED DIAMOND 4.SMALL WHEEL DAIMOND 5.LONG NEEDLE DAIMOND 6.RADIAL FISSURE BUR (ROUNDED SHOULDER) 7.MODIFIED BINANGLE CHISEL

ANTERIOR METAL-CERAMIC CROWNS SILICONE INDEX MADE BEFORE TOOTH PREPARATION TOOTH BADLY BROKEN DOWN, INDEX MADE ON WAXED UP DIAGNOSTIC CAST.

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO : 1 PLACEMENT OF DEPTH ORIENTATION GROOVES - ( 1.2MM ) THE LABIAL GROOVES CUT IN TWO SETS 1.ONE SET PARALLEL WITH THE GINGIVAL HALF OF LABIAL SURFACE 2.ONE SET PARALLEL WITH THE INCISAL HALF OF LABIAL SURFACE

ANTERIOR METAL-CERAMIC CROWN PREPARATION

STEP NO : 2 INCISAL REDUCTION- (2MM) ROUND –END TAPERED DAIMOND.

ANTERIOR METAL-CERAMIC CROWN PREPARATION Inadequate incisal reduction results in poor incisal translucency

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO : 3 LABIAL REDUCTION (INCISAL HALF) ROUND- END TAPERED DAIMOND.

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO :4 LABIAL REDUCTION (GINGIVAL HALF) ROUND-END TAPERED DAIMOND

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO : 5 LINGUAL REDUCTION (0.7 -1MM ) SMALL WHEEL DAIMOND.

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO :6 INITIAL PROXIMAL REDUCTION LONG NEEDLE DAIMOND

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO : 7 LINGUAL AXIAL REDUCTION ROUND - END TAPERED DAIMOND.

ANTERIOR METAL-CERAMIC CROWN PREPARATION STEP NO : 8 SMOOTHENING THE SHARP ANGLES

ANTERIOR METAL-CERAMIC CROWN PREPARATION

FACIAL MARGIN 1.DEEP CHAMFER 2.SHOULDER WITH BEVEL 3.SHOULDER 4.RADIAL SHOULDER

ANTERIOR METAL-CERAMIC CROWN PREPARATION DEEP (HEAVY ) CHAMFER PROVIDE 90-DEGREE CAVOSURFACE ANGLE WITH A LARGE –RADIUS ROUNDED INTERNAL ANGLE.

ANTERIOR METAL-CERAMIC CROWN PREPARATION RADIAL SHOULDER MODIFIED FORM OF SHOULDER SMALL RADIUS INTERNAL ANGLE WITH 90-DEGREE CAVOSURFACE

ANTERIOR METAL-CERAMIC CROWN PREPARATION SHOULDER WITH BEVEL THIS DESIGN CAN BE USED- GINGIVAL ESTHETICS ARE NOT CRICTICAL

ANTERIOR METAL-CERAMIC CROWN PREPARATION IMPROVED ESTHETICS ALL CERAMIC LABIAL MARGIN THIS ELIMINATES THE METAL COLLAR AT THE FACIOGINGIVAL MARGIN OF THE FINISHED METAL- CERAMIC RESTORATION

Type of burs for preparing

ANTERIOR METAL-CERAMIC CROWN PREPARATION IMPROVED ESTHETICS ALL CERAMIC LABIAL MARGIN THIS ELIMINATES THE METAL COLLAR AT THE FACIOGINGIVAL MARGIN OF THE FINISHED METAL- CERAMIC RESTORATION

ANTERIOR METAL-CERAMIC CROWN PREPARATION

READY METAL-CERAMIC CROWN CONSTRUCTION

POSTERIOR METAL-CERAMIC CROWNS

STEP NO : 1 OCCLUSAL REDUCTION FOLLOWED BY FUNCTIONAL CUSP BEVEL

POSTERIOR METAL-CERAMIC CROWNS STEP NO : 2 DEPTH ORIENTATION GROOVES

POSTERIOR METAL-CERAMIC CROWNS STEP NO :3 FACIAL REDUCTION- OCCLUSAL HALF

POSTERIOR METAL-CERAMIC CROWN STEP NO :4 FACIAL REDUCTION GINGIVAL HALF

POSTERIOR METAL-CERAMIC CROWN STEP NO: 5 PROXIMAL AXIAL REDUCTION

POSTERIOR METAL-CERAMIC CROWN STEP NO :6 LINGUAL AXIAL REDUCTION

POSTERIOR METAL-CERAMIC CROWN STEP NO : 7 AXIAL FINISHING

POSTERIOR METAL-CERAMIC CROWN STEP NO :8 GINGIVAL BEVEL

POSTERIOR METAL-CERAMIC CROWN

CAD/CAM system

What is CAD/CAM? Computer Aided Design(CAD) involves the use of computer hardware and graphics software to generate design drawings.

What is CAD/CAM? Computer Aided Manufacturing(CAM) is a system of automatically producing finished products by using computer controlled production machines.

What is CAD/CAM? CAD and CAM work together in that the digital model generated in CAD is inputted to the CAM software package. The CAM software needs to know the physical shape of the product(CAD model) before it can compose a proper set of fabrication instructions to a production machine.

CAD/CAM in Dentistry In dentistry CAD/CAM technology is used to produce a range of dental restoration

Crowns

Veneers

Inlays/Onlays

Implant Restorations

Bridges

Preparation 1. First and foremost requirement is a smooth preparation. Remember, ceramic crowns are a type of glass and any sharp angles or corners create stress points that can lead to fractures.

Preparation 2. Uniform reduction is necessary for optimal strength and esthetics. Thin areas compromise strength and esthetics.

Remember Uniform reduction results in optimum ceramic strength Adequate reduction leads to better esthetics Smooth edges result in lower stress Lower stress decreases potential for fracture Ceramic restorations require a passive fit Scanners read smooth preparations more accurately

Guidelines Uniform, circumferential, tooth reduction of mm Circumferential chamfer margin Occlusal reduction of mm Rounded line angles Reduce linguals of anteriors with football diamond to create concave lingual

Anterior Crown Preparation

Posterior Crown Preparation

Bridge Preparation

Preparation Tips

A feather edge is not recommended as it does not provide adequate reduction for the porcelain build- up. Do not utilize the through (or gutter) shoulder or 90° shoulder because the outer most edge may not be detected when scanned.

Impression There are many different systems of impression taking.

Impression Traditional methods involve using of tray and silicate or polyether material. When impression is taken the cast is scanned and data is send to the CAM centre.

Impression One of the method uses a red light laser to reflect off the tooth structure and requires the use of powder. The application of powder to the tooth is quick and simple, taking only seconds, and the powder is easily removed afterwards with air and water.

Impression Modern methods take many different approaches: use a continuous video stream of the teeth or use a camera that takes several views (stills), and use a strobe effect, as well as a small probe, that touche the tooth to give an optimal focal length. Those systems do not require the use of powder.

Impression

Design CAD/CAM operator uses a software tools to design restorations. His main concern is to achieve proper anatomy, margin, color, contact and occlusion requirements.

Design

Manufacturing (CAM) Once the final restoration is designed, the crown, inlay, onlay, veneer or bridge is milled from a single block of ceramic material in a milling chamber.

Manufacturing (CAM)

Staining&Glazing After the restoration is milled, it can be customized with stains and glazes to create a more natural look, before being fired in an oven (similar to ceramics and pottery), and then finished and polished.

Staining&Glazing

Cementation Cements can be classified based on the type of their matrix: -Phosphate (zinc phosphate, silico phosphate) -Polycarboxylate (zinc polycarboxylate, glass ionomer) -Phenolate (Zinc oxide–eugenol and EBA) -Resin (polymeric)

Cementation

Pros and Cons of CAD/CAM Pros: Easy to design and more time efficient than by hand (especially 3D images) Easy to make changes Increased accuracy

Pros and Cons of CAD/CAM Cons: Expensive software If machines break then it is time and money consuming Often difficult to use, the operator has to be highly trained

Thank you!!!