Tooth Preparation Guidelines for PFM Crowns

What is a PFM Crown?

A PFM crown is a tooth cap that has two parts. It has metal inside and porcelain outside. Dentists put these on teeth that need to be fixed. PFM means Porcelain Fused to Metal.

Why PFM Crowns Need Good Preparation

Good tooth prep helps your PFM crown:

• Stay in your mouth a long time
• Look nice
• Not hurt your gums
• Fit well with other teeth

Core Parts of PFM Crown Prep

Margin Design

The margin is the edge where the crown meets your tooth.

Types of Margins:

• Shoulder margin: Needs 1.2-1.5mm deep cut for porcelain
• Chamfer margin: Works well for metal edges

Where to Put the Margin:

• Above the gum: Good for gum health
• Below the gum: Only when needed for looks

Occlusal Reduction

Occlusal reduction means cutting the biting surface of the tooth.

You need to cut:

• 1.5-2.0mm on back teeth
• More (2.0mm+) if the person grinds teeth

Metal Occlusal Surfaces: If a person grinds their teeth a lot, the metal occlusal surface is best. Studies show metal tops have 30% fewer breaks over 5 years.

Learn about similar PFM Crown Metal Occlusal options at our lab

Axial Reduction

Axial reduction means cutting the sides of the tooth.

Good axial prep needs:

• 6° taper (not too steep, not too flat)
• At least 2mm height all around (called ferrule effect)

Did you know? A tooth with a 5° taper is 3 times stronger than one with a 20° taper.

Step-by-Step Guide to Prep a Tooth for PFM Crown

Step 1: Check the Tooth First

Before you start:

• Check if the tooth is still alive
• Look for old fillings
• Make sure there’s room next to other teeth

Step 2: Make Depth Cuts

• Use diamond burs to cut grooves
• Make them 1.5mm deep
• These help you see how much tooth to take off

Step 3: Cut Between Teeth

• Leave 0.5-1.0mm space from other teeth
• This helps the lab make dies that work well

Our Crown and Bridge Dental Lab can help with perfect fits

Step 4: Make Clean Margins

• Use small tools to make smooth edges
• No sharp angles
• Blend all lines

Step 5: Check Your Work

• Look at all sides
• Use a silicone index or scan to check
• Fix any spots that need more work

Help for Special Cases

People Who Grind Their Teeth

For bruxism (teeth grinding):

• Use metal occlusal surfaces
• Make sure the ferrule is strong
• Take off more tooth if needed

Talking to Your Lab

Tell your lab:

• What kind of margin you made
• If you want metal or porcelain edges
• How the bite works

Big Mistakes to Not Make

1. Too much taper (over 10°) – crown will fall off
2. Not enough height (less than 2mm) – crown will break
3. Bad margins – will hurt gums and get decay

Our PFM Crown and Bridge team can help fix common problems

What to Do After Prep

Make a Temp Crown

• Use good provisional crowns
• Make sure they fit well
• They keep the tooth safe until the real crown comes

Taking Good Impressions

• Use dual-arch trays for best fit
• Keep blood and spit away
• Get all margins clear

Lab Form Tips

• Send photos
• Write down bite info
• Mark all margin spots

PFM Crown Prep Data

Questions People Ask About PFM Prep

See our Front Tooth Porcelain Fused to Metal Crown options

Keys to Success with PFM Preps

1. Be precise – Don’t guess on depths
2. Check your work – Use tools to verify
3. Talk to your lab – They need good info
4. Make good temps – Keep the tooth safe

Why Good Prep Matters

When you prep a tooth well for a PFM crown:

• The crown will stay on for many years
• It will look nice
• It won’t hurt the gums
• The bite will feel good

Studies show that axial taper over 10° or ferrule height under 2.0mm makes crowns 40-50% more likely to fail.

Best Tools for PFM Preps

• Diamond burs: For fast, clean cuts
• Shoulder burs: For perfect porcelain margins
• Depth markers: To know how much to cut
• Silicone indexes: To check your work

Tips for Different Teeth

Front Teeth (Anteriors)

• Need more reduction (2.0mm+) for good looks
• Porcelain margins look best
• Smooth transitions are key

Back Teeth (Posteriors)

• Can use metal margins
• Metal chewing surfaces work well
• Need good ferrule for strength

Check our PFM Crown Posterior options for back teeth

Checklist Before You Finish

Make sure you:

• [ ] Cut at least 1.5mm off the top
• [ ] Have a 6° taper on the sides
• [ ] Left 2mm of tooth above the gum
• [ ] Made clean, smooth margins
• [ ] Have space from other teeth

What Makes PFM Crowns Last

Good PFM crowns can last 15+ years when:

• The prep has the right shape
• The bite is checked well
• The lab does good work
• The patient takes care of their teeth

Why Choose PFM Crowns

PFM crowns are still good because:

• They are strong
• They look nice
• They work well with gums
• They cost less than all-ceramic

Final Tips for Great PFM Preps

1. Take your time
2. Use the right tools
3. Look at all sides
4. Check your work
5. Talk to your lab

Good tooth prep means great PFM crowns that make patients happy!