Crowns

Question 1

Reductions for ACC

Answer 1

• 1-1.5mm shoulder
• 1-2mm axial reduction
• 1.5-2mm occlusal clearance
• Taper 6 degrees
• Contact is broken
• Path of insertion
• Axial wall height is greater than 3mm

Question 2

Reduction for Zirconia and metal

Answer 2

• 1-1.5mm occlusal
  
  • 1mm non-funtional cusp
  • 1.5 mm functional cusp
• Axial red
  
  • 0.5mm at gingival margin (shoulder width)
  • 1mm axial red coronal to shoulder

Question 3

Seating try in

Answer 3

• Eval all aspects of restoration on die (cast) prior to seating
  
  • Check intaglio for nodules
• Decide with pt if anesthetic is needed
• Remove provisional and cement
• Seat restoration
  
  • Follow steps in order CMO
    
    • Check and adjust proximal Contacts
    • Check Margins
    • Check and adjust Occlusion

Question 4

Luting with RMGI

Answer 4

• Follow manufacturers instructions
• Verify surfaces are clean and free of contaminants
• Do not dessicate tooth
• Place luting cement in restoration, covering entire intaglio and seat fully
  
  • Post- have pt bite on cotton roll to hold in place
  • Ant- Hold restoration in place
• Let cement set just until firm (not fully set) and remove excess
• Verify good proximal contacts, margins, occlusion

Question 5

Bonding

Answer 5

• Follow manufacturers instructions
• Verify surfaces are clean
• Prepare intaglio surface of final restoration according to manufacturers instructions
  
  • HF acid etch, silane, bonding resin- for many but not all ACC
  • Metal and zirconia must be treated differently if they are to be bonded
• Prepare tooth surface (etch, primer, and bonding resin
• Place resin cement to cover entire surface to be bonded and verify complete seating
• Remove excess and light cure from all directions
• Verify good proximal contacts, margins, occlusion and removal of excess resin

Question 6

When to lute

Answer 6

Metal and zirconia

It does not adhere to tooth

Luting doesnt give retention bc it doesnt bond, it just fills the space

Retention comes from prep

RMGI, RelyX, ZOE luting cement

Question 7

When to bond

Answer 7

• When there are concerns about retention
  
  • Short axial wall height
  • over tapered prep
• Bond porcelain (leucite or emax/lithium disilicate) bc material isnt as strong and may break
• Bonding provides micro-mechanical retention