What is a Dental Crown Made Of?
Currently there are three main types of crowns made with different materials currently used in dentistry today. Here we’ll explain what those three are and the main differences between them.
The cast gold crown is what many would consider to be the 'oldest' dental crown in use today. These crowns are made out of a noble or high-noble gold alloy (largely gold, platinum, and palladium, with a few other trace elements added to increase the hardness of the crown to make it more durable). Gold crowns have been used in situations where there is very little tooth structure (because the tooth doesn’t need to be reduced as much to allow for an adequate thickness of material) or when the junction where the crown and the tooth meet is below the gum line. Over time, the steadily increasing price of gold along with patient desires for a more esthetically pleasing result have resulted in fewer and fewer cast gold crowns being made.
As the desire for more esthetic treatment results grew, dental crowns changed to accommodate, and the porcelain-fused-to-metal (or PFM) crown became more prevalent. This crown has a cast metal coping (similar to the cast gold crown we described above, though with a lower gold content and a grey/silver color) with porcelain layered over top of the metal coping. Generally, there is a thin (~1-2mm) silver band visible on the side of the crown closest to the tongue/roof of the mouth. While these crowns do look more esthetically pleasing than a cast yellow gold crown (imagine that on one of your front teeth for a minute), they do require the tooth to be more aggressively shaped to allow room for the metal coping, the opaque porcelain used to block out the dark color of the metal, and then the more translucent porcelain to give the tooth a beautiful lifelike appearance. Over time, we’ve also seen these crowns fail at the interface between the porcelain & the metal, especially when these PFM crowns are used on back teeth where chewing forces are the greatest. A third concern is long-term cosmetic problems. Have you ever seen someone smile and notice a dark line or halo at the gumline of a tooth? Perhaps you’ve noticed this on yourself as well! This is due to the metals in the coping of a PFM crown leaching out into the surrounding tooth structure and into the gum tissue, staining it over time. Also, if a person experiences some degree of gum recession or continued eruption of the tooth over time (which does happen even as an adult), the junction where the crown and the tooth meets becomes visible. While this may not be terribly noticeable on a back tooth, it can certainly be a cosmetic issue on a front tooth when you smile.
Over the past couple of decades, dental ceramics have come a long way in terms of strength, the accuracy with which they can be created, and their esthetics. Now, most ‘modern’ crowns are made solely using ceramic. These are generally divided into two categories, zirconia, and glass-ceramics (though I won’t bore you with the details at this point). Both types of crowns are typically fabricated digitally using a computer, milled using a highly accurate mill, and then fired in a porcelain oven (anywhere from 30 minutes to 11 hours depending on the type of ceramic). With these more modern materials, we have the ability to create a beautiful crown that looks life-like, doesn’t stain the surrounding tooth & soft tissue, and yet is durable enough to hold up under extreme chewing forces.
Want to learn more? Come visit our office on the south side of Indianapolis where we use our on-site dental lab with a 3D printer, a 5-axis mill, and more to create beautiful high-quality crowns for our patient’s smiles! While most offices require two weeks to get a crown back from the lab, we are consistently able to have a beautiful and highly accurate crown ready for our patients within 24 hours, sometimes even the same day! Come see what our patients in the Homecroft, Southport, and Greenwood areas are smiling about!