If you are on this page, chances are that you have realized that quality matters in dentistry! Dental crowns are not all created equal. Most of the dental crown failures that occur are due to technical dentist errors. Our doctors believe that continued education and research on the best products for our patients leads to treatments that almost always surpass the lifespan of the average dental crown.
Causes of Crown Failure
Crown failure happens for many reasons, but product failure is almost never the true cause. For the most part crowns fail because of two technical errors. The first technical error relates to the fit, cementation and bonding of the post, buildup, or crown itself. The second technical error is caused by the wrong type of crown selected for the patient’s occlusion or bite. The proper selection of a crown is imperative because biting forces can exceed the properties of some kinds of crowns. Also, tooth preparation that subjects the crown to over excessive biting forces can in turn cause the need for a root canal on that tooth. Different types of crowns and locations require different preparation, bonding and cementation techniques. This is why Dr. Koeppel has a vast array of cementation and bonding agents, to fit each case specifically.
Sometimes crowns become loose or fall off due to the bonding process, materials used, fit of the crown, or using expired materials. Matching the proper cement to the bonding agent is critical, and keeping the area clean from saliva, blood, and water during the bonding process is imperative. Over-preparation or under-preparation may also be the culprit. If this is the problem, re-cementing the crown will not fix the problem.
Crowns that have been on for long periods of time can become loose due to decay growing underneath the crown. If a little decay is mistakenly left under the crown during preparation or an ill-fitting crown leaks, bacteria can continue to grow or work itself underneath the crown. Some of the older cements wash out, causing a space between the crown and tooth where bacteria and decay could migrate. The bacteria byproducts cause the decay and discoloration around and under the existing crowns.
Discoloration can be described as unsightly black lines surrounding the top margins of the crown. Many crowns become discolored because of metallic defects. Newer crowns become discolored because of leaking margins. The use of porcelain, emax, or lava crowns with tight margins can overcome this problem, as well as handling the preparation on the tooth correctly.
When a new crown is placed, and immediate sensitivity to hot or cold foods is felt, this could be the cause of inadequate boding procedures allowing for the food or liquid to get inside of the crown. If the bite is not adjusted properly it can also cause tooth sensitivity. Being meticulous in adjusting the bite is important.
Pain associated with biting down or chewing may mean that the preparation of the tooth was done inadequately. The crown may have too much height, and may not have been mounted on an articulator during the fabrication process. Stone models are poured and mounted on articulators (jaw simulators) to enable occlusal experts to gather the data needed for an optimal fitting crown. Because Dr. Koeppel and his master ceramists use articulators, this common error is always avoided.
Replacement of Failed Crowns
Replacement of a failed crown is a fairly easy and straightforward process. The old crown is removed and decay is excavated (removed). A crown buildup (repair of the tooth structure) is usually utilized to stabilize the tooth. A new impression is taken, and a new crown made for optimal fit is placed. During the interim the patient wears an esthetically correct temporary crown that maintains the space and gum tissue levels. If other complications exist, more treatment may be necessary.