anterior full coverage crowns Flashcards
What are contraindications?
Other more conservative options
Poor oral hygiene
Uncontrolled caries
Unstable and active perio
Structurally compromised affecting retention
Lead to loss of pulp vitality
Ceramic can cause TSL of opposing teeth (crowns have a greater coefficient of friction)
What are types?
Metal-ceramic
Porcelain fused to metal (PFM)
High strength ceramic (Zirconia)
-monolithic
-veneered w feldespathic veneer
Dentine bonded porcelain (feldespathic or lithium disilicate)
Acrylic
Resin based composite
What are indications?
Aesthetics
Broken down
TSL
Trauma
Atypical shape and hypoplastic
Milled crowns and attachments for RPDs
Retainers for cantilever bridge
Alter occlusion
How are the crowns fabricated?
Metal-ceramics and PFM- cast metal and sintered overlay of porcelain
Monolithic- CADCAM milled in green state and sintered
Veneered (Zirconia core)- same as monolithic then sintered overlay of porcelain
Dentine bonded porcelain- sintered or CADCAM milled
Acrylic and resin based composite- manual layering or CADCAM milled
Additional techniques- pressing and casting
What is a metal-ceramic or PFM?
Metal core and ceramic veneer
Deep labial reduction (1.5mm)
Shallow palatal prep (0.7mm)
Compromised aesthetics due to metal substructure (can look dull)
Option for exposed palatal metal surface (can reduce coefficient of friction)
What are dentine bonded crowns?
Thin layer of glass ceramics relying on bonding to dentine for strength
Shallow reduction w chamfer margin conservative prep (0.7mm)
Ideal for minimally restored teeth needing crowns for aesthetics
What is an all ceramic crown (pressed)?
Designed in wax and transferred into mould (die) where molten glass is pressed
Results in strong core or full contour crown
Eg. Empress I, II (Ivoclar vivadent)
What is an all ceramic crown (glass infiltrated ceramic core system)?
Alumina core formed using slip casting
Core is porous and then infiltrated w glass
Resulting in dense core
Eg. In ceram spinel, in ceram zirconia
What is an all ceramic crown (high strength core system)?
Pure alumina or zirconia
What is an all ceramic crown (CADCAM milled)?
Computer made design is fed to milling machine
Crown is milled form ingot
Eg. Cerec
Reduced human error
Can use more uniform materials
Can use more complicated materials eg. zirconia, titanium
Compatible w digital intra oral scanners
Which crown should you use and when?
Dentine bonded porcelain- minimally restored teeth, for aesthetics, no major occlusal interferences/loads
High strength ceramic- structurally compromised teeth, for aesthetics, greater occlusal loading
Metal-ceramic (PFM)- structurally compromised teeth, greater occlusal loading, combine w RPD, lower coefficient of friction
