DS3102 L32 Zirconia and Emax Fixed Prosthodontics
How do we bond the zirconia prosthesis?
- ask lab to blast the fitting surface with 25-50 microns aluminum (can use 3M Cojet and ROCatec) - clean the crown with alcohol - after try in, clean it with ivoclean - treat surface with scotchbond universal or use ivoclar monobond - cement with nexus 3 dual cure resin cement
Why must we "clean" the fitting surface of a zirconia crown after the try in? What do we use?
After the try in, the zirconia fitting surface is contaminated with saliva and the associated calcium phosphate ions. The phosphate bonds to zirconia oxide bonding sites on the fitting surface which prevents silane from bonding to the crown and thus the resin from adhering to it. Use ivoclean on zirconia crowns after try in to remove CaPO4 contamination.
Describe the prep of a EMax prep (ant vs post).
Ant: - palatal/labial (1 to 1.5mm) - incisal (1.5-2mm) Posterior: - occlusal (2mm) - everywhere else 1mm)
Describe the prep of a monolithic zirconia prep (ant vs post).
Ant: 0.5 all around (labial mostly 1mm) Post: 0.5 to 1mm all around (ferrule atleast 7mm)
What is scotchbond?
Applied to prep and crown surface - contains silane and allows bonding to crown. It also has acidic monomers that will etch cut enamel on the prep (eliminate need to etch prior to bond). Paint inside of crown then crown prep with it.
When should you adjust the emax crown?
Do not check occlusion or adjust it until crown is cemented (it gets strength from bond to tooth - or else it will snap).
T/F You should etch the crown prep with phosphoric acid prior to placing the zirconia crown
FALSE - scotch bond will etch the surface enough - phosphoric acid will let phosphate ions bond to zirconia oxide (preventing silane bonding).
T/F You can use emax prosthodontics for posterior teeth
False - although they can both handle wear and tear; zirconia provides lasting results. Emax not strong enough to handle occlusal force of teeth further back than second premolar.
T/F Zirconia is so tough that it will always wear the opposing dentition
False - it usually won't effect the opposing dentition unless you've adjusted the surface with a bur (use a fine bur)
How should you adjust a zirconia crown?
Fine grit cuts more efficiently - once adjusted, use a special silicone bur to get high shine. DO NOT make a concavity in the occlusal surface - maintain the convexity of the occlusal aspect.
Why do we silanate things?
It creates a layer that allows the crown to bond to the resin material (better adherence to tooth).
Why do we have to be careful with the ivoclar monobond etch and prime?
It has a strong etch and MUST be washed and dried to prevent pulpitis (if placed on tooth it will damage it).
What is emax made from? Describe its durability.
Lithium disilicate ceramic and have a strength of 380-400 megapascales (MPa)
What is zirconia made from? Describe its durability.
Made using a power with crystalline properties - strength of 800-1200MPa
What is opalite?
Monolithic zirconia (no metal, no layering, etc) and requires less preparation space than traditional crowns. It is far more aesthetic than traditional PFM restoration. Flexural strength of 1100MPa and clinically unbreakable.
How do they make opalite restorations?
The zirconia crowns and bridges are designed digitally and milled from zirconia using CAD/CAM technology before being polished to a smooth finish with a similar lustre to a full gold crown for minimal abrasion.
T/F If your prep has retention, you likely dont need bond (can just use rely x unicem)
True
T/F Scotchbond is better as you should have the crown etched with HF
True - all you have to do it try it in, wash and then dry.
What are the two techniques to EMax bonding?
1: - ask lab to hydrofluoric acid etch the fitting surface of the crown - silinate (apply silate to crown; scotchbond) - apply nexus 3 2: - Ivoclar monobond etch and prime (if you forget to ask the lab to etch the crown) - silinate (scotchbond - can use 3M universal adhesive) - apply nexus 3
How should we adjust the emax crown?
Use ceramaster coarse polisher to finish, polish and super polish porcelain and enamel. Careful blend of diamond particles to great a smooth and glaze like surface
Which is more aesthetic? Emax or zirconia?
Zirconia comes in various shades and looks similar to natural teeth due to slight transparency of its material. EMAX is more TRANSLUCENT and provides the BEST MATCH for pt surrounding natural teeth.