A porcelain fused to metal crown, commonly called a PFM crown, is a dental cap made with a metal shell on the inside and a tooth-colored porcelain layer on the outside. It combines the strength of metal with the appearance of natural tooth material, and for decades it has been considered the gold standard for restoring damaged teeth. PFM crowns typically cost between $800 and $1,400 per tooth and have one of the highest survival rates of any crown type.
How a PFM Crown Is Built
A PFM crown has two distinct layers. The inner layer is a thin shell, called a coping, cast from a metal alloy. This coping fits snugly over what remains of your natural tooth and provides the crown’s structural backbone. The outer layer is dental porcelain, shaped and shaded to match your surrounding teeth.
In the dental lab, a technician first creates a wax model of the metal coping, then casts it in a special alloy designed to bond with porcelain. The alloy has a higher melting point and different expansion rate than standard gold alloys, which prevents the porcelain from cracking as temperatures change. After the metal framework is finished and polished, the technician layers porcelain onto it and fires the crown in an oven at roughly 960°C (1,760°F). The porcelain fuses directly to the metal surface in much the same way enamel is bonded to household cookware. The result is a single, solid restoration.
Strength and Durability
PFM crowns are strong. In lab testing, PFM crowns on molars withstand an average force of about 1,940 newtons before fracturing, and on premolars about 1,241 newtons. For context, normal chewing force on back teeth ranges from roughly 400 to 700 newtons, so a PFM crown provides a comfortable margin of safety for everyday use.
That said, newer zirconia (all-ceramic) crowns have surpassed PFM in raw fracture resistance. Zirconia premolar crowns averaged about 2,831 newtons in the same testing, and zirconia molars averaged about 2,517 newtons. This doesn’t mean PFM crowns are fragile. They’ve been used successfully for decades and remain more than strong enough for most situations. But for teeth that are severely damaged or bear unusually heavy bite forces, zirconia may offer an edge.
How Long PFM Crowns Last
PFM crowns have an impressive track record. A systematic review of clinical studies found that PFM crowns had approximately a 99.5% survival rate after five years. All-ceramic crowns, by comparison, showed about a 92% survival rate over the same period. With proper oral hygiene, many PFM crowns last 15 years or longer. The metal coping resists breakage well over time, and the porcelain surface holds up to normal wear, though it can chip if you habitually grind your teeth or bite hard objects.
The Dark Line at the Gumline
The most recognized drawback of PFM crowns is a grayish line that can appear where the crown meets your gum tissue. This happens for two reasons. First, the metal coping blocks light from passing through the crown the way it would through a natural tooth. Healthy gums get some of their pink color from light scattering through tooth structure underneath. When an opaque metal shell sits there instead, the gum tissue above the root can look gray or purplish, sometimes called the “umbrella effect.”
Second, metal particles from the alloy can slowly release into the surrounding soft tissue over years, contributing to discoloration. Crowns with a higher content of non-precious metals tend to cause more of this darkening. On back teeth, this is rarely noticeable. On front teeth, especially if your gumline is visible when you smile, it can be a cosmetic concern. All-ceramic crowns avoid this problem entirely because they transmit light similarly to natural tooth structure, keeping the gums a healthy pink.
How Much Tooth Is Removed
Getting a PFM crown requires your dentist to reshape the tooth to make room for both the metal and porcelain layers. On the front-facing surface, about 1.5 millimeters of tooth structure is removed: roughly 0.5 mm for the metal coping and 0.7 mm for the porcelain veneer, plus a small margin. On the biting edge or top of the tooth, about 2 mm is taken down to prevent the crown from looking bulky or unnaturally long.
This is slightly more reduction than some all-ceramic systems require, because the PFM design needs space for two separate materials rather than one. The process typically takes two appointments. At the first visit, the tooth is reshaped and a temporary crown (usually stainless steel) is placed. At the second visit, a few weeks later, the temporary is removed and the finished PFM crown is cemented permanently.
PFM vs. All-Ceramic Crowns
The choice between a PFM crown and an all-ceramic crown often comes down to location in the mouth, cosmetic priorities, and budget.
- Aesthetics: All-ceramic crowns look more natural, especially on front teeth. They transmit light like real enamel. PFM crowns need an opaque layer to hide the metal underneath, which can make them appear slightly less lifelike and may cause gum darkening over time.
- Strength: Both types are strong enough for normal function. Zirconia ceramics now match or exceed PFM in fracture resistance, though PFM remains highly reliable on back teeth.
- Longevity: PFM crowns currently have better long-term survival data, largely because they’ve been in clinical use longer. The 99.5% five-year survival rate is hard to beat.
- Cost: PFM crowns run $800 to $1,400, while all-porcelain and zirconia crowns can range from $800 to $3,000. PFM tends to sit at the lower end of that spectrum, making it a cost-effective option.
- Metal sensitivity: A small number of people have allergies to nickel or other base metals used in some PFM alloys. If you have known metal sensitivities, an all-ceramic crown avoids that risk entirely.
Where PFM Crowns Work Best
PFM crowns remain a solid choice for back teeth, particularly molars and premolars, where strength matters more than appearance. They’re also commonly used for dental bridges, where the metal framework provides the rigidity needed to span a gap between teeth. For front teeth or anywhere aesthetics are the top priority, all-ceramic options generally produce a more natural result. Your dentist will factor in the tooth’s location, how much healthy structure remains, your bite forces, and your budget when recommending one type over another.