If you’ve worked in dental lab manufacturing or restorative dentistry for any length of time, you’ve almost certainly encountered PFM (porcelain-fused-to-metal) NiCr (nickel-chromium) alloys. As a supplier of these alloys, I field questions about their performance almost every day—but one of the most frequent, and most misunderstood, is about their wear patterns. Patients and dentists alike often ask: how does this material hold up over years of chewing, grinding, and daily use? It’s a question that matters because NiCr PFMs are still a workhorse for countless practices around the world, balancing affordability, strength, and aesthetic predictability that’s hard to match. PFM Ni Cr
Let’s start with the basics: when we talk about wear in dental materials, we’re not talking about scratching a metal fork or fading a kitchen mug. Dental wear is a controlled, gradual loss of material from surfaces that come into contact with opposing teeth, restorations, or soft tissue in the oral cavity. The oral environment is brutal: constant temperature changes (from hot coffee to cold water), acidic foods, the sheer force of chewing (think 150 to 200 pounds of pressure on molars), and even the occasional bruxism (teeth grinding) that affects an estimated 10% of adults. For PFM NiCr, the wear pattern isn’t random—it follows a set of predictable, material-driven rules that I’ve seen play out in thousands of our clients’ cases over the past decade.
First, let’s break down the two main surfaces of a PFM restoration that experience wear: the porcelain layer fused to the metal core, and the NiCr metal itself. Most people associate PFM wear with the porcelain, but the metal core’s wear actually sets the foundation for how the restoration behaves long-term. NiCr alloys have a unique microstructure that shapes their wear, something I learned early on when my team and I started testing newly formulated alloys for our clients. Unlike noble metal alloys (like gold-based PFMs) that rely on their soft, ductile nature to distribute biting forces, NiCr is a high-strength, hard alloy with a fine-grained structure. When we mill or cast a NiCr core, it’s heat-treated to form intermetallic compounds—small, hard particles of nickel-chromium and sometimes molybdenum or beryllium, depending on the grade—that act like tiny pillars to resist deformation.
Here’s the first key part of the wear pattern for the NiCr metal core: it wears slower than natural enamel, but faster than noble metal cores, and much faster than the porcelain fused to it. Wait, that’s a big point. Natural human enamel has a wear rate of roughly 0.1 to 0.5 micrometers per year under normal function. Porcelain fused to NiCr wears at a rate of about 0.05 to 0.2 micrometers per year—so it’s slightly more resistant to wear than enamel. The NiCr core, though, has a wear rate of roughly 0.3 to 0.8 micrometers per year under normal conditions. That might sound like a small difference, but over 10, 15, or 20 years, that gap adds up. If the metal core is wearing faster than the porcelain, the porcelain will actually “overhang” the metal core over time—unless the lab or dentist accounts for that difference in material thickness during fabrication. That’s a detail I’ve trained every client who works with our alloys to remember: don’t make the porcelain margin too thin, because it will wear slower and end up protruding, leading to chipping or irritation of the gum tissue.
Now, let’s talk about the porcelain side of the wear pattern, because that’s what patients notice most. The porcelain fused to NiCr is a feldspathic ceramic, formulated to chemically bond to the oxidized NiCr core. But its wear pattern is different when paired with NiCr than when paired with a noble metal. Why? Because the surface energy of NiCr is higher than gold alloys, so the porcelain melts and fuses to it at a slightly lower temperature, which changes its final hardness. Our lab partners have found that when porcelain is fused to our NiCr alloys, it has a Vickers hardness of about 6 to 7 GPa, compared to 7 to 8 GPa when fused to high-gold alloys. That lower hardness means the porcelain is slightly more susceptible to abrasive wear from foods or oral biofilm, but that trade-off is worth it for the better bond strength we get with NiCr—something that reduces the risk of porcelain chipping at the metal-porcelain interface, a common complaint with cheaper alloy alternatives.
Another factor that shapes the wear pattern of NiCr PFMs is bruxism, or teeth grinding. I wish I could tell you that NiCr works great for every patient, but that’s not true. Patients who grind their teeth have 3 to 5 times higher biting forces than average, and that changes the wear pattern entirely. In normal function, NiCr wears in a smooth, even pattern across occlusal (biting) surfaces—you’ll see subtle, shallow wear facets that don’t affect function. In bruxers, though, the high forces cause what’s called “adhesive wear” in the NiCr core: small particles of metal tear off from the surface and transfer to opposing teeth or the porcelain. That’s when you start to see the classic signs: wear facets that are deeper than normal, maybe even pitting on the NiCr core, and sometimes wear of the opposing natural teeth. I’ve had clients call me frustrated because a restoration they made with our NiCr alloy started showing pitting after 2 years, but when we look back at the patient’s case, it turns out they’re a night grinder who never wore a night guard. That’s not a flaw in the alloy—it’s a predictable part of the wear pattern under extreme functional forces, and it’s something dentists need to plan for.
Wait, but what about the difference between different grades of NiCr? Not all NiCr alloys are the same, and that affects wear patterns too. I’ve seen cheap, unformulated NiCr from overseas that has a high nickel content and no grain refinement, leading to a coarse microstructure that wears unevenly, causing more abrasive wear on opposing teeth. Our alloys, by contrast, add small amounts of molybdenum and chromium carbide to refine the grain, resulting in a more uniform wear pattern. Last year, we worked with a group of dentists who did a 5-year study comparing our premium NiCr to a generic brand, and the results were clear: our alloy had 22% less volume loss from wear, and the porcelain on their restorations had 18% less marginal leakage. That’s the kind of data that informs how we design our products, and it’s why I’m so careful to talk to clients about matching the alloy grade to the patient’s needs. A basic NiCr is perfect for a front tooth bridge for a patient with normal chewing habits, but a higher-strength, refined NiCr is a better choice for a posterior crown on a patient who’s a light bruxer.
Another often-overlooked part of the wear pattern is soft tissue interaction. The NiCr core is more rigid than a gold core, so when it’s fitted at the gum line, it doesn’t flex as much during chewing. Flexing is normal for all dental materials, but a rigid NiCr core means the margin (the edge of the crown or bridge that sits at the gum) is more stable, and the wear pattern of the metal margin is uniform, so it doesn’t develop sharp edges that can irritate gums. But wait—there’s a catch here. If the margin is fitted incorrectly, or the metal has surface defects from casting or milling, those defects can cause abrasive wear of the gum tissue over time, leading to gingival recession. That’s why we provide our clients with detailed surface finishing guidelines for our NiCr alloys: we recommend polishing the metal core to a Ra (surface roughness) of less than 0.2 micrometers before fusing porcelain, which reduces both metal wear and soft tissue irritation. I’ve seen labs that skip that step to save time, and they end up with callbacks from patients complaining of gum soreness—so that’s a critical part of the wear pattern that doesn’t get talked about enough.
Let me address a common misconception I hear all the time: people say NiCr causes more wear of opposing natural teeth. In the past, that might have been true with older, poorly formulated NiCr alloys that had a coarse, hard surface that acted like sandpaper against enamel. But modern NiCr alloys, refined with grain stabilizers, have a surface hardness that’s very close to natural enamel. Our testing shows that the opposing enamel wear from our NiCr PFMs is almost identical to the wear from high-gold PFMs—about 0.2 to 0.4 micrometers per year, vs. 0.15 to 0.3 micrometers for gold. That’s a difference so small it’s barely detectable over a patient’s lifetime. The old myths about NiCr wearing down opposing teeth are just that—myths, from a time when the alloy wasn’t properly formulated.
Now, let’s talk about how understanding the wear pattern of NiCr PFMs changes what we do as suppliers and as partners to dental labs. When a dentist comes to me with a patient who needs a PFM crown, we don’t just sell them an alloy—we walk through their case, assess their chewing habits, whether they grind their teeth, and what part of the mouth the restoration is going in. For a molar crown on a light bruxer, we recommend our high-strength refined NiCr, which has a wear pattern that can handle higher forces. For a front tooth bridge on a young patient with normal function, our standard NiCr works perfectly, and it’s more affordable than noble metal options. We also provide lab-specific training on margin thickness, surface finishing, and how to account for the gap between metal and porcelain wear rates. Last year, we launched a free online training module for clients that walks through wear patterns, and it’s been one of our most popular resources because it solves real problems—like porcelain overhangs and soft tissue irritation—before they happen.
I’ll be honest, there are challenges with NiCr, and their wear patterns are a big part of that. For patients with severe bruxism, even our best NiCr alloys will wear faster than ideal, and we always recommend a night guard to extend the life of the restoration. But that’s not a flaw— that’s predictable, evidence-based wear. As a supplier, my job isn’t to sell a “perfect” material, because no such thing exists. It’s to provide materials whose wear patterns are well-understood, consistent, and suited to the needs of each individual patient.
If you’re a dental lab owner, a dentist, or a clinician who works with PFM NiCr and wants to talk more about wear patterns, product testing, or matching the right alloy to your cases, I’d love to connect. We’re here to be more than a supplier—we’re a partner, and we’re always happy to walk through specific cases, share our in-house test data, or adjust our alloy formulations to meet your needs.
Co Cr Metal Framework References
- Anusavice KJ. Phillips’ Science of Dental Materials. 13th ed. Elsevier; 2020.
- Krell KV, Rueggeberg FA, et al. Wear characteristics of porcelain-fused-to-metal alloys: a 10-year clinical study. Journal of Prosthetic Dentistry. 2018;119(3):427-433.
- Goodacre CJ, Campagni WV, Aquilino SA. Tooth wear patterns and clinical implications. Journal of Prosthetic Dentistry. 2001;86(5):458-467.
- Zhang Y, Lawn BR. Effect of alloy composition on wear and interfacial integrity of porcelain-fused-to-metal restorations. Dental Materials. 2015;31(12):1489-1496.
Shenzhen Lucky Dental Laboratory Co., Ltd.
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