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Five Common Questions And Answers About Dental Crowns

Five Common Questions And Answers About Dental Crowns

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Since crowns are one of the more common restorations that people need on their teeth, we are regularly asked the question, “Do I really need a crown?” It is a completely fair question that we encourage you to ask. We strongly feel that with any dental or medical treatment, you should be fully aware of the reasons for treatment, different options, and consequences of proceeding with treatment or not. In this article I will answer some of the more common questions about dental crowns that I frequently hear from patients. I also encourage you to send me an email at info@downtownmontrealdentistry.com or call the office if you have any other questions that are not answered here.

1. Why do I need a crown?

There are a variety of situations that may require a tooth to be restored with a dental crown. The following are the most common:
a. Large filling: When a tooth has a cavity or a fracture that involves half the width of the tooth or more, it may need to be covered with a crown. This is because the remaining tooth around the large filling is so weak that it is prone to fracture.
b. Root canal: Root canal treatment leaves the tooth hollowed out and predisposes the remaining tooth to cracking. So, a tooth that has had a root canal should be restored with a crown immediately to prevent it from fracturing. This is especially important when it is a back tooth.
c. Broken cusps: Sometimes a cusp (the pointy part) of a tooth will fracture due to trauma. These are the parts of the tooth that take on a lot of the chewing stress, and typically simple fillings are not strong enough to replace them for the long term.
d. Undesirable appearance of teeth: Teeth that have an unacceptable appearance due to colour, shape, or spaces between teeth can be made to look very natural and beautiful with crowns. This is a different reason than the previous three since it is more based on esthetics than function, but it can still be a very valid reason depending on the situation.

Figure 1. The procedure for a dental crown

Figure 1. The procedure for a dental crown

2. What are my options?

In some cases, while a crown is one option, there can be others. You might opt for a filling instead. Keep in mind, however, that a filling does not prevent you from needing a crown later on. Also, if a substantial portion of your tooth needs filling it may not give you the same kind of protection as crowns do. If the filling is extremely large, it can cause the tooth to break, making it irreparable.

3. What if I wait or do nothing?

A few different scenarios can occur if you choose to not proceed with treatment:
a. Nothing may happen, the tooth could remain as is for many years
b. The tooth could chip or crack and may require a repair.
c. In more rare cases, it may break in a way that would require a root canal
d. The tooth may fracture in a way that renders it not repairable and it would have to be extracted.

4. Is a root canal needed?

Most teeth that have root canals should have crowns, but not all teeth that need crowns require root canals. The need for a root canal depends on whether the tooth is infected or inflamed and painful, or if a very significant portion of the tooth is missing.

How long does the crown last?

The research on dental crowns indicate that most will last an average of 10 to 15 years. However, there are factors that influence this figure. A person who has a high risk of cavities (someone who has to have a couple of fillings each year for example), or grinds their teeth, or has poor oral hygiene habits may find that their crown lasts less than the average. On the other hand, we have some patients who have had the same crowns for 30+ years. The point is that the average lifespan is just that, an average. It should be taken as a guideline, but cannot be considered a guarantee. The mouth can be a very hard environment for the teeth, with chewing pressure and repetitive stresses from the muscles of the jaw. Add to that some of the negative factors listed above and you have the reasons why some crowns fail early. But with a well designed crown and some effort to improve oral care, we can maximize the lifespan of any restoration.

Dental X-Rays, Do I Really Need Them?

 

Doctor, do I really need to take dental x-rays? This is a question frequently posed by our patients and one that requires thoughtful consideration. The reason why people may question or refuse the need for dental x-rays often relates to the issue of safety. No one wants to expose themselves to radiation needlessly, and on this point everyone can agree. However, we cannot overlook the benefits of dental x-rays: They allow us to detect small problems of the teeth and bone of the jaws before they become big problems. So what is the balance? How often can we safely take x-rays and how often should we?

 

A typical dental x-ray image. Smile!

A typical dental x-ray image. Smile!

Before answering the question, we must understand a bit about x-ray exposure. Radiation is measured in units called millisieverts. This is a metric measurement, so it uses a similar scale to what we use for distance. One millimetre is 1/1000th of a metre. Dental x-rays are measured in microsieverts. So just as a micrometre is 1/1000th of a millimetre, a microsievert is 1/1000th of a millisievert. To put it another way, it is 1000 times less.

The fact is that radiation occurs naturally all around us, to the point where we are naturally exposed to about 4 millisieverts every year. This number increases if we live in a part of the world with longer sun exposure, at higher elevations, if we fly on airplanes, watch television, or smoke cigarettes. A typical digital dental x-ray examination of 4 bitewing x-rays is 0.8 microsieverts. Remember that is 5000 times less than your average natural exposure yearly dose! Dental x-rays are among the lowest sources of diagnostic imaging x-rays used.

 

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The only films we use are digital, which correspond to the 6th row from the top. As described in the chart, 18 to 20 films is 0.0039 mSv, meaning one film is less than 0.0008 mSv.

Now that doesn’t mean that we need excessive amounts of images. For new patients, Dr. Seminara will review your history, examine your mouth and teeth then decide whether you need radiographs and what type. For most patients, this will mean bitewings and selected periapical images. These can give us valuable diagnostic information about the teeth, bone, roots and other structures of the jaws. Once we know your general dental status, a recall schedule can be fixed with regular x-rays as needed.

A Bitewing X-ray

A Bitewing X-ray

A Periapical X-ray

A Periapical X-ray

 

 

 

 

 

 

 

The average patient in our office who is at low risk (someone who get cavities infrequently) would be recommended to have bitewing x-rays done once every 18 to 24 months. A patient at higher risk would be recommended to have them done every 6 to 12 months. More are taken for patients with advanced needs, such as gum disease or root canals. Emergency visits may also require images to help diagnose the cause of the acute problem. We take care to limit exposure by using digital x-ray sensors and specials machines that specifically target the mouth area, reducing exposure to other body parts. In fact, the body is covered by a protective lead apron for this very purpose.

Dr. Seminara’s x-ray recommendations are always based on your specific individual needs and the standard of care as prescribed by the Order of Dentists of Quebec and the Canadian Dental Association. Our goal is to take as few as necessary to keep your teeth and mouth in perfect health!