PFM crowns (porcelain-fused-to-metal): when they are still a sensible choice

A PFM (porcelain-fused-to-metal) crown is a cap with a thin metal inner shell covered by tooth-coloured porcelain. It is still a sensible choice in many situations: back teeth, bridges, teeth next to existing PFM work, or teeth that will support a partial denture. Its main drawbacks are possible chipping of the porcelain and a grey line at the gum.

How a PFM crown is built

PFM crowns, also called metal-ceramic crowns, have been used for decades. Each one is made in a dental laboratory from an impression (a precise mould) of your prepared tooth; our guide to the main types of dental crowns and when you need one gives the background. The crown is built in layers:

1. The coping: a thin metal shell that fits the tooth closely and carries most of the chewing load.
2. The opaque layer: a thin coat of porcelain that hides the grey colour of the metal.
3. The outer porcelain: layers baked in a furnace to recreate the shape and colour of a natural tooth.

Margin design

The margin is the edge of the crown, close to the gum. Traditionally, a narrow metal collar runs around it. In a porcelain-margin (collarless) design, porcelain reaches the edge on the visible side, which lowers the risk of a grey line but needs very precise laboratory work.

Which metals are used in PFM crowns?

Dental alloys, meaning mixtures of metals, are usually grouped into three families:

• High-noble alloys: mostly gold, with platinum or palladium. They resist corrosion and are very well tolerated by the gum.
• Noble alloys: a smaller share of precious metals, often palladium or silver.
• Base-metal alloys: such as nickel-chromium or cobalt-chromium. They are very rigid and widely used.

A true allergy is uncommon, and nickel is the metal most often involved. If you react to cheap jewellery or a watch buckle, mention it at your consultation so that a nickel-free alloy or a metal-free crown can be considered.

When a PFM crown is still a sensible choice

Metal-free crowns such as zirconia and E.max are now the first choice for many teeth, yet PFM remains useful in several situations:

• Back teeth that hardly show when you smile or talk, where its long track record is reassuring.
• Bridges, especially longer ones, where a metal framework allows strong yet slim joints between the teeth.
• Teeth next to existing PFM crowns or bridges, so that colour and surface stay consistent.
• Teeth that will hold a partial denture, because rests for the clasps can be built precisely into the crown (see acrylic, metal-framework and flexible partial dentures).
• Very little space between upper and lower teeth: a metal biting surface with porcelain only on the visible side keeps the crown thin and tough.

Your dentist weighs the position of the tooth, your smile line (how much tooth and gum you show when you smile), your bite and your preferences.

When another material may suit you better

PFM is usually not the first option in these situations:

• A front tooth in a smile that shows a lot of gum, especially if the gum is thin.
• A confirmed allergy to a component of the alloy.
• Heavy grinding (bruxism) with porcelain on the biting surface. Monolithic zirconia is often preferred, as described in our article on zirconia crowns and the treatment step by step.
• A single front tooth that needs the most lifelike translucency, where E.max is often chosen.

For a point-by-point table of both materials, see our comparison of zirconia and porcelain-fused-to-metal crowns.

The grey line at the gum: causes and solutions

A dark or grey line at the gum is the most common complaint about older PFM crowns. The usual causes are:

• Gum recession over the years, which exposes the metal collar.
• Thin gum, through which the metal shows as a bluish-grey shadow.
• A darkened root under the crown, for example after old root canal treatment.

It is mainly an aesthetic issue, but a dark edge can also signal decay or a gap under the crown, so have it examined. If the crown is sound and on a back tooth, many people keep it; on a visible tooth, it can be replaced with a metal-free crown or a PFM crown with a porcelain margin.

Getting a PFM crown: what is different

The usual crown sequence applies (preparation, impression, temporary crown, fitting), generally over two visits. Specific to PFM:

• Slightly more tooth reduction than for monolithic zirconia, because room is needed for both metal and porcelain.
• For bridges, the metal framework is sometimes tried in before the porcelain is added, which can mean an extra short visit.
• Careful shade matching, since the porcelain must hide the metal.

The preparation is done under local anaesthesia, so you feel pressure rather than pain. Mild sensitivity or a tender gum for a few days is common and usually settles with simple painkillers.

Care, lifespan and what affects the cost

A well-made PFM crown commonly lasts many years, often well beyond ten. It is rarely the metal that fails: decay at the margin, gum disease, grinding or a chip in the porcelain are the usual reasons, as explained in our guide to how long crowns and bridges last.

• Brush along the gum line twice a day and clean between your teeth daily.
• Wear a custom night guard if you grind your teeth.
• Avoid biting ice, hard sweets or packaging.
• Keep regular check-ups: metal blocks X-rays, so decay under a PFM crown is harder to see on a radiograph, and the dentist also checks the edges directly.

There is no single price. The cost depends on the alloy, whether it is a single crown or a bridge, the position of the tooth, any treatment needed first such as a build-up, root canal treatment or gum care, and the laboratory work. A consultation gives you a clear, personalised plan.

PFM crowns at Ajam Dental Clinic in Tripoli

Ajam Dental Clinic offers PFM crowns alongside zirconia and E.max ceramic crowns, so the material can be matched to each tooth. Dr. Abdel Rahman Ajam holds a DDS and an MSc in Aesthetic and Prosthetic Dentistry, and his focus includes crowns, bridges and dentures. Patients come to our clinic on Fouad Chehab Boulevard from across Tripoli — Al-Qobbeh, Bab al-Tabbaneh, Jabal Mohsen and Dam wa Farez — as well as from Beddawi, Minieh and the rest of North Lebanon.

Read more about our crowns, bridges and other prosthodontic treatments. To have a tooth or an old PFM crown assessed, contact us on WhatsApp to book a consultation.

This article provides general information for patients. It does not replace an examination by a dentist, who can advise you on your own situation.