How materials selection can impact restorations

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