What are crowns?
Throughout life, our teeth take a tremendous amount of wear and tear. Sometimes, the tooth structure can fracture or crack under the stress of a bite. Sometimes, the tooth can also decay over time. To restore the structural integrity, function and appearance of the tooth, we design specialized caps called crowns that also double up and protect the remaining tooth structure.
How are crowns made?
Crowns are made to be extremely specific to the tooth. To do so, we first create an “impression,” or blueprint of the original tooth. This impression is then further adjusted to account for a more precise shape and fitting within the mouth.
Conventionally, impressions are made using sticky impression material that is then used to mold a rigid model, but with significant advancements in dental imaging, at Bloom Holistic Dentistry we now use intraoral scanners to take extremely accurate and precise digital impressions of teeth, allowing us to make any changes to the structure and alignment in real time on the computer.
After a model (either physical or digital) is created, there are two ways to manufacture the crown itself: at a dental lab, or using in-house milling technology. If your model is sent to a dental lab, the crown is created and shipped back to the dental office in about 1-2 weeks. We occasionally use the lab for more specialized structures, but for the majority of crowns, we produce them in-house using a milling unit to carve out the crown structure from the digital impression out of a material block, and then heating them in a specialized oven at temperatures exceeding 1200*F!
Why should you have your crowns produced in-house? Well firstly, we as your dental provider have full control of the shape, fit and material being used giving us a new level of quality control of the items we place in your mouth. Secondly, we dramatically cut down the waiting time that we can deliver a crown. Rather than having a “temporary” protective cap that is usually poor fitting and has high risk of damage and being lost, we can create the crown, prepare the tooth, and fit the crown in your mouth all within a few hours during the same visit!
What materials are crowns made of? Which one should I get?
The purpose crowns serve is two-fold: to ensure a strong surface that can withstand years of biting force, and to look as much like the rest of the teeth. Based on this, different materials have been used to create crowns.
Historically, crowns were using porcelain fused metal. The benefit at the time was being able to use strong substances (metals) while shading the porcelain component to match the rest of the teeth. The big problem as we would come to realize is the amount and types of metals labs would use. Alloys including aluminum, nickel and even arsenic were used to create these crowns and this created significant concerns of releasing metal to the body over the lifespan of the crown as it went through its wear and tear. Today, labs are more sensitive to the types of metals being used for porcelain crowns, however the quantity and composition of the metal alloys vary dramatically between labs.
In order to eliminate any metal substrate being implanted in the body and improve biocompatibility, two newer materials have been used to make crowns: zirconia and ceramic.
Zirconia crowns are made up of the elemental form of zirconium and zirconium oxide. They boast having extremely high tensile strength in a lightweight form, and can be shaded to match the rest of the teeth. Zirconia crowns, due to their high density, reflect light very nicely to give a naturally appearing shape and have the benefit of being highly biocompatible in the body. This material is a great choice for teeth that are under a lot of stress, such as molars.
But for an even more lifelike appearing material, all-ceramic crowns made of lithium disilicate make for an exceptionally strong and highly biocompatible material. Since the material is slightly less dense than zirconia, ceramic crowns allow a very small amount of light to pass through, just like normal teeth. Because of this added aesthetic property, ceramic crowns are an exceptional choice for someone looking for the strength and biocompatibility of zirconia with the added bonus of looking as close to natural teeth. All-ceramic crowns make for a great material that will stand the test of time.
Read more about our same-day crown service in our Restorative Dentistry and Dental Technology services pages.