The Case for Crowns

I frequently have discussions with my patient’s about the appropriate time to place a crown on a tooth. Many times this relates to teeth that have large existing fillings in them. We know from clinical trials that fillings are only successful long term when a certain portion of healthy tooth structure remains around the filling. As I frequently comment, fillings do exactly what they say they do. They fill space. They do not absorb any of the impact of function of chewing. Therefore a tooth with a large filling can exist in a weakened state. The tooth in the photo below has a moderately sized amalgam filling with cracks that run in between the teeth in the front and back.

Many people have existing amalgam (silver) fillings from their teenage years that fit this criteria. In some cases, these amalgam fillings have been replaced with a large resin composite filling. No matter the material, we know the tooth is suspect to breaking. It just becomes a matter of time before that tooth will break. We want to try and strengthen these teeth before they break because we can never be sure where they will break. In some cases, they can break deep into the nerve necessitating a root canal. In other cases, they can break deep under the gums necessitating a gum surgery to repair. In a worst case scenario, a tooth can break to a point at which is unrepairable which leads us to extraction and replacement.

Here is a photo of a tooth that we treated here in our office last week. This tooth has a large amalgam filling. One of the functional cusps of the tooth fractured. When the cusp fractured, it broke deep into the nerve and underneath the gums. This tooth was not restorable and required extraction. We are now examining replacing the tooth with an implant after the area has healed. This tooth could have been saved with a crown had it been placed prior to the fracture.

This photo demonstrates a phenomenon often seen in these situations. If you notice, the part of the tooth that fractured was natural tooth structure and the amalgam filling still remains. This is what we usually see in these situations. That part that fractures is rarely the filling, but the weakened area of natural tooth structure.

Patients often ask me when they should have their teeth with large fillings crowned. This is a complex question that can vary from patient to patient. Certainly, there are times in which we can predict that a tooth is more subject to fracturing than another, but this is a very inexact science. Most of the time we have no clue when a tooth with a large filling will fracture. It could happen tomorrow or ten years from tomorrow. The bottom line is that we would like to crown the tooth before it breaks. I generally recommend to patients that we proceed with crowning a tooth when the proverbial stars align. When a patient has the time to undergo the crown procedure, one of the stars has aligned. When a patient’s insurance benefits (if applicable) are adequate, another star has aligned. Finally, when a patient is able to make financial arrangements for their part of the fee, the third star has aligned. When all of these things come together, it is time to proceed with crowning a tooth with a large filling.

Sometimes, a tooth just can’t wait until all the stars align and pain or sensitivity begins. This can often be attributed to cracked tooth syndrome. These teeth with large fillings and fracture lines can sometimes become sensitive to cold, bite or both. In these instances, we should proceed with crowning the tooth immediately. If treatment is delayed, the likelihood of a catastrophic breakage is increased. If you notice this phenomenon, call our office ASAP to set up an emergency evaluation!