Excellent question! And the answer is……… (Read on to find out). How long a crown lasts is not as simple as a measure of time. Many factors contribute to a crowns longevity such as what the crown is made of, environment in which the crown lives and home care. This article will attempt to shed some light on the life of a crown.
What is a crown?
A crown as defined by the American Dental Association (ADA) is:
“An artificial replacement that restores missing tooth structure by surrounding the remaining coronal tooth structure, or is placed on a dental implant. It is made of metal, ceramic or polymer materials or a combination of such materials. It is retained by luting cement or mechanical means.”
Wow, that’s a bit too technical for most folks. If I were to quote that every time I had to explain a crown I would create more questions than I would answer. Simply put a crown is like a baseball cap that goes over the tooth to protect and restore the tooth underneath. Crowns can be used to restore broken or worn teeth, correct misaligned teeth or change the color of dark teeth. It can be made of porcelain, metal or a combination of both. Crowns on natural teeth are bonded or “glued” to the underlying natural tooth using a dental cement.
What are crowns made of?
Three popular crown materials are porcelain fused to metal (PFM), full gold or all porcelain.
In PFM crowns the crown is made in two parts, a metal covering called a coping onto which porcelain is baked in a high temperature oven. The porcelain forms the final shape and color of the crown to match the adjacent teeth. For many years this has been the most popular and widely used type of crown. Although very strong the porcelain can break away from the metal coping. With time the metal coping can begin to show causing a dark line to show at the edge of the crown.
There are numerous types of all porcelain crowns. What type is used depends on what it is being used for. Zirconium, a form of porcelain, is extremely strong and fracture resistant and has taken over as the most popular type of crown used for restoring back teeth. More esthetic porcelains, although not as strong, may give a much more life-like restoration when used in the front of the mouth.
Full gold is exactly what it says it is, full gold. The entire crown is made of gold or gold colored alloy. As you can imagine this crown is extremely strong and will not break. This makes it ideal for teeth in the extreme back of the mouth. The down side for most patients is the color.
What environment is best for crowns?
Crowns placed in areas of the mouth that undergo extreme amounts of stress and pressure, such as the back of the mouth, will potentially have a shorter life span, but that’s not always the case. By contrast crowns in the front that receive less pressure may last longer. A crown in the mouth of a petite person may last longer than the same crown in the mouth of a powerlifter. Personal habits such as tooth grinding, ice chewing and using your teeth for tools will shorten a crowns life span. Diets high in acid and refined sugar will also shorten a crowns life span.
How do you take care of a crown?
Home care is one of the most important factors in the longevity of a crown. Despite what most patients think a crown can still fail due to decay. Although the crown itself cannot decay the natural tooth underneath can form decay at the junction of where the crown and tooth meet. Regular flossing is key to keeping this area clean because brushing alone cannot reach between teeth where most cavities start. A diet low in sugar and acid is also key. If tooth grinding is a problem, especially at night, a night guard may be necessary to protect teeth and crowns from breaking. Avoiding damaging habits, ice chewing for example, is important to crown longevity.
So, as you can see it’s not as simple as you may think to answer the question “How long will a crown last?” With so many unknown factors involved the most accurate and reliable answer I can give my patients is “I don’t know."