PFM crowns are a popular choice in dentistry because they combine the toughness of metal with the natural appearance of porcelain. As a dentist, it’s important to have expertise in PFM crown installation and removal.

Here are some tips, techniques and common challenges that will help you perfect your PFM crown installation and removal procedures.

Close up photo of a porcelain-fused-to-metal (pfm) crown against a black background.

PFM Crown Preparation

Here are some pivotal points to ensure your tooth preparation is on point:

Use diamond burr for smooth finish
Keep reduction even for proper crown thickness
Avoid undercuts that could cause fitting issues

Taking Impressions

It’s not just about the materials you choose but also about your impression-taking technique:

Choose high-quality impression material
Time the setting process carefully
Use retraction cord to get clear margin impressions

Why Temporaries are More Than Just a Placeholder

Temporal crowns play a critical role in PFM crown installation, serving not just as a stop-gap but as a blueprint for the final crown. They offer a sneak peek into how the final restoration might look and perform, making their precise fabrication and fit paramount.

What Is The Best Cement To Use For PFM Crowns?

Cementation is the final—but far from the least—critical step in PFM crown procedures. Each choice made here can significantly impact the longevity and success of the restoration.

Pick biocompatible cement to avoid allergic reactions
Choose cement based on patient needs and crown type
Try fitting without cement first

Several factors should be considered when selecting the best cement to use for PFM crowns:

Strength and Durability:
- High Strength: PFM crowns require a cement with high compressive and shear bond strength to withstand the forces of biting and chewing.
- Durability: The cement should resist wear and tear over time, preventing microleakage (the seepage of bacteria and fluids between the crown and the tooth) which can lead to secondary caries (decay) and sensitivity.
Biocompatibility:
- Minimal Irritation: The cement should not irritate the pulp (the living tissue within the tooth) or cause any adverse reactions in the surrounding tissues.
Aesthetics:
- Translucency: Some cements are more translucent than others, which can be important for maintaining the natural appearance of the tooth, especially in anterior (front) teeth.
- Color Matching: The cement’s color may need to be chosen to blend seamlessly with the underlying tooth structure.
Ease of Use:
- Application: The cement should be easy to mix, apply, and remove any excess.
- Working Time: The cement should have an adequate working time to allow for proper seating and removal of excess before it sets.
Type of PFM Crown:
- Metal Content: The amount of metal in the PFM crown can influence cement selection.
- Margin Design: The type of margin (e.g., chamfer, shoulder) may also affect the choice of cement.

Common Cement Types for PFM Crowns:

Resin-Modified Glass Ionomer: Offers a good balance of strength, biocompatibility, and fluoride release (which helps prevent secondary caries).
Resin Cements: Provide excellent bond strength and aesthetics, but may require careful isolation and etching procedures.
Conventional Glass Ionomer: Primarily used for temporary cementation.

When and How to Remove a PFM Crown

The removal of a PFM crown, whether for adjustments or replacement, requires a strategic approach to prevent damage to the underlying tooth structure.

Cut carefully to protect the tooth
Use ultrasonic tools to loosen cement
Keep patient informed to reduce anxiety

When PFM Crowns May Need Removal

Failure of the Crown:
- Fracture: The porcelain can chip or fracture, exposing the underlying metal.
- Decay: Decay can occur under the crown if the margin wasn’t sealed properly.
- Loose Crown: The crown may become loose due to wear and tear, or if the underlying tooth structure deteriorates.
Aesthetic Concerns:
- Discoloration: The metal substructure can cause a dark line at the gumline.
- Wear and Tear: The crown may show signs of wear and tear, such as chipping or cracking.
- Outdated Appearance: The crown may no longer match the patient’s current cosmetic goals.
Dental Issues:
- Tooth Decay: Decay may occur on the tooth structure adjacent to the crown.
- Gum Disease: Periodontal disease can affect the tissues around the crown.
- Bite Problems: The crown may interfere with the bite, causing discomfort or wear on other teeth.
Medical Necessity:
- Metal Allergies: Some patients may develop allergies to the metals in the PFM crown.
- Interference with Medical Procedures: The metal in the crown can interfere with certain medical imaging procedures.

How PFM Crowns are Removed

Isolation: The tooth and surrounding area are isolated with a dental dam to keep the area clean and dry.
Removal of Cement:
- Mechanical Removal: Special dental tools are used to carefully remove the cement that holds the crown in place.
- Ultrasonic Scalers: In some cases, ultrasonic scalers may be used to help loosen the cement bond.
Crown Removal: Once the cement is removed, the crown is carefully lifted off the tooth.

Why PFM Crowns May Need to be Removed

To Address Underlying Issues: Removal allows the dentist to assess the health of the underlying tooth and address any problems like decay or gum disease.
To Replace with a More Modern Restoration: PFM crowns can be replaced with more modern options like all-ceramic crowns, which offer improved aesthetics and biocompatibility.
To Improve Oral Health: Removing a failing crown can prevent further complications and improve the overall oral health of the patient.

Incorporating these insider secrets into your practice can elevate the level of care you provide, ensuring that each patient leaves your clinic with a smile that’s not only beautiful but enduring. As dental professionals, our mission is to blend artistry with precision, and knowledge with empathy, to create restorations that are not just functional, but truly transformative.

“The true mastery in dental restoration lies not just in the technical skill but in the attention to the finer details that personalize and perfect the patient’s experience.”

Porcelain-Fused-to-Metal (PFM) Crowns: What Dentists Need to Know