What Exactly is a Crown?

Most people have heard of the terms “crown” and “cap” in regard to dentistry (they are interchangeable, and dentists prefer the term crown), but few actually understand what a crown is.  This blog will explain this, along with why they are necessary, what types of crowns are available in modern dentistry, and what to expect if you are in need of one.

What is a crown?

There are actually two meanings of the word “crown” in dentistry, which can sometimes make things confusing.  We will define both here, and the rest of the blog will pertain only to the second definition.

1. Crown – the portion of a tooth exposed to the mouth, which excludes the roots (even any root structure that is visible through gum recession). This definition describes an anatomical portion of a tooth.  The crown is covered in enamel.  Under this definition, every tooth has a crown.
2. Crown – a dental restoration of a tooth in which all of the enamel has been removed and replaced with a new material. Crowns can be made out of metals, ceramics, or temporary materials.  A crown should completely cover the entire exposed portion of the tooth, and the edge (margin) of the crown typically rests near the gum line of the tooth.

Why do certain teeth need crowns?

• Very large cavities – In some cases, the integrity of the tooth is undermined by a very large cavity. Once all of the decay has been removed from the tooth, there must be an adequate amount of solid, healthy tooth structure to support a filling.  If there is not enough tooth structure remaining to hold a filling, then the entire tooth must be covered by a crown in order to restore it to its proper shape for chewing.  In this situation, if a filling were placed instead of a crown, it could only be considered a short-term solution at best.
• Fracture – The enamel covering a tooth is one solid, continuous layer. A visible fracture or crack means that the enamel is no longer able to do its job of protecting the tooth from bacteria, food, and chewing forces.  Interestingly, cracked teeth do not always cause pain.  A crown’s role in “fixing” a cracked tooth is the total replacement of the enamel layer with a new solid, continuous material, which splints the underlying tooth structure together.
• Lack of adequate coronal tooth structure – Just as a very large cavity can deprive a tooth of the necessary amount of tooth structure, a large filling or even missing tooth structure can do the same. The crown restores the tooth to its original shape, size and strength to provide proper function.
• Root Canal Treatment – When a tooth has had a root canal, the nerves and blood vessels have been removed from the inner, hollow chamber of the tooth. They are replaced with a filling material called gutta percha.  Because the tooth no longer has a blood supply, it no longer has a source of hydration and becomes dried out and brittle.  This brittleness makes the tooth high risk for cracking.  A crown is placed over a tooth that has had a root canal in order to prevent such cracking so that you can keep the tooth for a long time.  A root canal is a significant investment in the life of a tooth.  If the tooth is not properly covered and protected with a crown, that investment could be wasted.

What are the different types of crowns?

There are many different materials available for crowns today.  Each material has pros and cons, listed below.  What is most important is that your dentist select the proper material for each individual tooth.  At Timberlake Dental, we prioritize each patient as an individual with distinct and specific needs.  You will never get a “one size fits all” recommendation.  Our doctors take all of the pros and cons of each material into consideration when selecting the right crown for your particular needs.

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What can I expect at my dental appointment for a crown?

• Traditional lab fabricated – If your crown is being made in a dental lab by a professional, certified dental lab technician, you will experience a two-appointment process. At the first appointment, the tooth is prepared for the crown under local anesthetic.  You should be numb and experience no discomfort during the preparation process.  Once the doctor has achieved the proper preparation for your tooth based on the crown selected, either an impression or a 3D scan is taken.  Both of these serve to communicate the exact shape of the prepared tooth from the doctor to the lab.  The lab uses this to fabricate the prescribed crown.  The process typically takes 2-3 weeks.  During that time, you will wear a provisional or temporary crown to replace the enamel and cover the tooth.  The temporary crown and your bite should feel comfortable after the initial post-operative sensitivity has worn off (on average, a few days).
  You will return for your second appointment after we have received your crown from the dental lab.  At this visit, the temporary crown is removed, the underlying tooth structure cleaned, and the new crown fitted to your tooth.  An x-ray is taken to confirm that the crown fits properly and allows no leaking of saliva or bacteria under the crown.  The bite is adjusted, if necessary, and then the crown is cemented onto the tooth.  You need to have a little caution when eating and cleaning the new crown for the first 24 hours.  Afterward, you return to business as usual, eating and cleaning it like you would a natural tooth.
• Same-day in-house crowns – A new trend in dentistry is same-day crowns. This technology eliminates the need for two appointments, the 3 week waiting period, and a temporary crown.  The same-day crowns are made with a CAD/CAM milling machine that works with 3D technology to create a physical crown out of digital information.  One limitation to same-day crowns is that they can only be made out of one material, so they are unable to make crowns that contain two types of materials like the porcelain-fused-to-metal crowns.  They are also limited in the customization allowed to create the perfect match to your natural teeth.  For this reason, they may not be selected as the right type of crown for front teeth.
  The tooth is prepared by the dentist in the same way, and instead of having a provisional crown made, you simply wait in the office while the crown is being milled by the CAD/CAM machine.  Once it is completed, the crown is fitted to your tooth in the same process as noted above, and the same instructions apply.

Do You Need a Crown?

Call our office at 940-382-1750 to set up a consultation with Dr. Chowning.  He will discuss the reasons your specific tooth needs a crown and go over the available types of crowns with you.  Together, you will select the crown that will best fits your needs.