How materials selection can impact restorations
Jan 08, 2019| 
While you can trust your lab to choose the right materials for your restorations, it’s important to understand material limitations because each case is unique and many situations call for tradeoffs. Here are some advantages and disadvantages of some of the most common types of lab materials.
Porcelain fused to metal (PFM)
PFM crowns have a long and tested track record; their ability to provide predictable, lasting results has made it a popular material selection for dentists over the years.
Advantages
Been around for a long time and proven to work
High flexural strength for large bridges
Great adaptation to margins
Blocks out a dark Dentin
Disadvantages
Can show gray line at margin over time
Not indicated for limited occlusal surface or limited lingual buccal space
Can cause allergic reaction in individuals with metal allergies
Requires a minimum of 2.0 mm occlusal reduction to build optimal esthetics
Cases with a lot of occlusal reduction require building up the tooth with alloy for porcelain support, which increases the cost
IPS e.max
IPS e.max provides very esthetic restorations, but it’s not a one-solution-fits-all product.
Advantages
All ceramic with world-class esthetics
Track record of successful cases
Can be hand waxed for better margin adaptation
Suitable for crowns and veneers, ideal on multi-unit cases requiring both
Great for inlays/onlays
Cut-back technique allows technicians to custom shade crowns and add custom internal characterizations
Very strong, 400 megapascals
Disadvantages
Challenging to block out a dark Dentin; may require chairside block out cement
Requires bonding
Not indicated for bridges
Zirconia
Zirconia is becoming one of the most popular materials for dental crowns, but it still has limitations dentists should be aware of.
Advantages
Inert material
All-ceramic crown
Blocks out a dark Dentin
Indicated for multi-unit bridges
No alloy cost means a fixed price
Very strong for posteriors, 765-1,100 megapascals
Cementable
Can be layered for esthetics
Disadvantages
Can’t cut and solder a bridge once it’s fabricated to salvage it
Rigid, not ideal for large span bridges
High translucency zirconia can’t block out a dark Dentin as well as PFM
Can be hard to adjust or cut off, requires special burs