The Wonderful World of Crowns in Dentistry

January 2007

By: Dr. Scott R. Harden

Invariably, while at social gatherings, someone will often approach me and ask a question about their dental needs. Before long, the conversation will draw the attention of other people. This recently happened again during Super Bowl XLI. At the tail end of laughter over a clever Budweiser commercial, I was approached and the question came, “can I ask you a question about my teeth? I was told by my dentist that I needed a crown for my tooth and I was wondering if you thought this would be a good idea or not”. In the modern world of dentistry, intra-oral cameras, digital x-rays, and multimedia including animated graphics that clearly demonstrate dental procedures all offer tremendous mediums for patient education, and it is surprising any patient can leave a dental office today without all of their questions answered.

“My tooth has a large filling and it has a fracture on the side of it”, she explained. Her next question was one of the most sincere questions I am ever asked — “can’t he just patch up the tooth with a filling?” My focused response to her question was to define the potential need for a crown based upon her diagnosis.

There are (6) indications for crowns in dentistry (“caps”).

1. LARGE FILLINGS. Composite fillings (“white fillings”) rival tooth structure in their physical properties and offer great restorative solutions for many dental related problems. However, I have seen many composite restorations fail because they were inappropriately placed into the tooth when there was not sufficient tooth structure remaining to support the filling. Large fillings can easily pull away from the tooth when biting pressure is placed upon it which leads to accelerated decay under the filling and can lead to tooth loss. Fractures can also develop in weakened areas of the tooth and can often lead to tooth loss as well. The rule of thumb is fillings less than 50% of the volume of the tooth are adequately supported, and fillings greater than 50% of the tooth require full coverage crowns.

2. CRACKS WITH SYMPTOMS. Other indications for placement of a crown (“cap”) include a condition known as “CRACKED TOOTH SYNDROME” or CTS for short. According to the International Association for the Study of Pain, CTS is a “brief, sharp pain in a tooth, often not understood until a piece fractures off the tooth.” It is an elusive problem and difficult to diagnose because fractures do not show up on x-rays and will often be deeper in the tooth and not observable clinically. The diagnosis must be based upon symptoms such as pain upon chewing or biting lasting a few seconds’ duration and noticed especially when pressure on the tooth is released. The most important factor in adequately responding to patients’ symptoms is dentists’ awareness that cracks in teeth can occur. Early detection is important because of the likely progression of the crack and the possibility of a secondary bacterial infection. Permanent stabilization of the crack with a full crown is the best course of treatment, and serves the tooth like a cast on a broken bone – only it does not come off. If the crack is too severe, root canal therapy or extraction of the tooth may be the only possible therapy.

3. CRACKS WITHOUT SYMPTOMS. Not all fractures cause pain in the tooth. However, they can still be just very serious and require careful diagnosis. Fractures can be horizontal, vertical or diagonal in nature. Dentists can sometimes observe fractures by use of light shined on the tooth or through the tooth (“transillumination”). Dentists may observe fractures inside the tooth upon removal of an old filling. The location of cracks and their severity relate directly to the need for crowning.

4. TEETH TREATED BY ROOT CANAL THERAPY. Teeth treated by root canal therapy and have minimal endodontic access openings or no previously placed restoration and do not have any cracks present can serve well with only a composite (“white”) filling. More typically, a root canal treated tooth will have a large filling and/or cracks present, and require a crown.

5. TEETH WITH COMPROMISED BONE SUPPORT. When teeth are missing and require replacement by a partial denture (metal framework with plastic teeth), it is often necessary to crown teeth and use specific anchors to support the denture. If the supporting bone and gum tissue has receded on an anchor tooth, sometimes splinting two teeth together for support is done to add stability to the anchor teeth.

6. SMILE MAKEOVER. Esthetic upgrading is one of the most common reasons that crowns are placed today. Most patients want to have their teeth look “normal” in color and shape. Frequently, crown or veneer placement is the only way to achieve that goal. The improvement is both esthetic appearance and function provided by properly placed all-ceramic or porcelain-fused-to-metal crowns. This process should be discussed with alternative treatment options including bleaching, orthodontics, and direct resin bonding.

Crowns are one of the most common dental therapies. There are several biological reasons to place crowns as discussed in this article. As a patient, it is important for you to be educated as to why crowns are the preferable treatment. The real challenge of dentistry is to combine function and esthetics and simultaneously create a long-lasting result for the patient.