STONE V PRINTED MODELS

COMPOSITE CROWNS eg Gradia

COMPOSITE CROWNS

5 Year old composite –it deteriorates with time

Composite also wears with the passage of time – this overlay is 12 years old and is nearly worn through on the occlusal surfacee

TEMPORARY CROWNS• Prevent sensitivity• Protect the pulp

• Prevent tissue overgrowth• Maintain the spacial position of the prepared tooth in the arch during

crown fabrication• Diagnostic

• Acrylic v composite• Never use an ultrasonic or apply leverage for removal!

Make the temps before you take the impression

Never use Vaseline as a separating medium

CROWN CEMENTATION

• Check there is no residual cement on the prep• Check the contact points• If not seating ensure you did not leave any sharp edges on the prep• If still not seating try using eg Fit Checker to see if there are any

casting blebs on the fit surfaces and remove• Probably the crown will never fit and it was a distorted or poor

impression

DIFFERENTIAL WEAR

DIFFERENTIAL WEAR HARDER MATERIALS ABRADE SOFTER ONES.

ENAMEL,DENTINE, COMPOSITE, GOLD AND PORCELAIN ALL WEAR AT DIFFERENT RATES. THE RESULTANT UNEVENESS OF THE OCCLUSAL LINE RARELY INTRODUCES PREMATURITIES IN CENTRIC BUT OFTEN INTRODUCES INTERFERENCES IN

ECCENTRIC MANDIBULAR MOVEMENTS

IF THE OCCLUSION OF A CROWN OR BRIDGE IS ADJUSTED ALWAYS ENSURE THAT THE OCCLUSAL SURFACE IS RE-GLAZED OR REPOLISHED TO AVOID WEAR

Crown adjustment

Glazed porcelain Surface texture following adjustment with diamond bur

Porcelain surface after polishing with the Meisinger porcelain polishing kit

e.Max and Zirconia in particular require specialist finishing kits

1 ZIRCONIA FINISHING & POLISHING - CRA SEPT 16

TEMPORARY CROWNS

• Any missing bits of the tooth being treated can be replaced and moulded with red carding wax. If the whole tooth is missing preformed acrylic moulds are manufactured

• For your ‘mould’ you can use alginate, putty or specific products such as ‘Template’

• I suggest using sectional trays – they can be purchased or simply cutting lower acrylic trays

• If using putty you must use a tray – there is too much risk of flexure• For complex cases you can have laboratory fabricated and called blowdowns or

suckdowns. They are either hard or soft• The material of choice is either acrylic or composite• There are lubricants available if you are unsure if the temp will come off easily.

Although materials such as Vaseline or ‘Slaycris’ can be used, beware as they are not water soluble and difficult to remove off the prep – a problem if you are taking impressions after. Water soluble lubricants such as Wink (Pulpdent) or K-Y Jelly

• Trimming – maintain contact points and do not over-trim to ensure there is no gingival overgrowth

• Temporary cements

Temporary crowns

The wax up duplicated in the temporary crowns

YOU MUST HAVE PARALELL PREPS FOR ONE PIECE TEMPS

LUTING CEMENTS

ZINC OXIDE EUGENOL

UNTIL VERY RECENTLY, USING A TEMPORARY CEMENT WHICH HAD ZINC OXIDE EUGENOL AS A COMPONENT WAS NOT ADVISED IF A RESIN CEMENT WAS TO BE USED AS A LUTING AGENT AS THE EUGENOL COMPONENT WOULD INETREFERE WITH THE POLYMERISATION

OF THE RESIN. RECENT STUDIES HAVE SHOWN THAT IF THE TEMPORARY CEMENT HAS BEEN IN PLACE FOR LONGER THAN 2 WEEKS, THE EUGENOL WILL HAVE DE-ACTIVATED. SIMILARLY IF MICROABRASION IS AVAILABLE, THE EUGENOL LAYER IS SUPERFICIAL AND

REMOVED WITH THIS TECHNIQUE OF CLEANING THE PREPARATION PRIOR TO FINAL CEMENTATION

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ZINC PHOSPHATE

POLYCARBOXYLATE

GLASS IONOMER

RESIN MODIFIED GLASS IONOMER

COMPOSITE RESIN LUTING CEMENTS

• Conventional• Self adhesive

• Self etch• Panavia

Conventional

Self adhesive

Self etch

Panavia

CROWN REMOVERS

FINISHING LINES

CHAMFER

SHOULDER

SHOULDER BEVEL

FEATHER

THE ROLE OF GROOVES TO IMPROVE RETENTION OF CROWNS

TO IMPROVE RETENTION IN ANTERIOR TEETH THE GROOVES SHOULD BE PLACED MESIALLY AND DISTALLY - ON POSTERIOR TEETH BUCCALLY AND

LINGUALLY. TO INCREASE RETENTION FURTHER IN THE POSTERIOR SEGMENTS, ADDITIONAL GROOVES CAN BE PLACED MESIALLY AND DISTALLY

PREP DESIGN