Crowns

Crowns are an ideal restoration for teeth which have been broken, or have been weakened by decay or a very large filling. The crown fits right over the remaining part of the tooth, making it strong and giving it the shape and contour of a natural tooth. The crown, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line. Crowns are indicated for a variety of reasons such as:

• To protect a weak tooth (for instance, from decay) from breaking or to hold together parts of a cracked tooth
• To restore an already broken tooth or a tooth that has been severely worn down.
• To replace an existing restoration that covers more than half of the tooth.
• A crown is indicated after root canal therapy to "reinforce" the tooth.
• To cover and support a tooth with a large filling when there isn’t enough remaining tooth structure.
• To hold a dental bridge in place
• To cover misshaped or severely discolored teeth
• To cover (restore) a dental implant

There are three types of materials including: metal, all-porcelain, or a mixture of metal and porcelain.

Metal crowns are an excellent option. Compared with other crown types, less tooth structure needs to be removed with metal crowns, and tooth wear to opposing teeth is kept to a minimum. Metal crowns withstand biting and chewing forces well and probably last the longest in terms of break down. Also, they rarely chip or break. The metallic color is the main drawback. Metal crowns are a good choice for out-of-sight molars and for patients who clench or grind their teeth.

Porcelain-fused-to-metal dental crowns can be color matched to your adjacent teeth (unlike the metallic crowns). However, more wearing to the opposing teeth occurs with this crown type compared with metal crowns. The crowns porcelain portion can also chip or break off. Next to all-ceramic crowns, porcelain-fused-to-metal crowns look most like normal teeth. However, sometimes the metal underlying the crown's porcelain can show through as a dark line, especially at the gum line and even more so if your gums recede. These crowns can be a good choice for front or back teeth.

All-ceramic or all-porcelain dental crowns provide the best natural color match than any other crown type and may be more suitable for people with metal allergies. However, they are not as strong as porcelain-fused-to-metal crowns and they wear down opposing teeth a little more than metal crowns. All-ceramic crowns are the most esthetic choice for front teeth.

To fabricate a dental crown takes two appointments. At the first appointment, the dentist will prepare the tooth to the ideal shape for the crown. This will involve removing 1-2 millimeters of the outer surface and leaving a strong inner 'core.' The amount of the tooth removed will be the same as the thickness of the crown to be fitted. Once the tooth is shaped, the dentist will take an impression of the prepared tooth, one of the opposite jaw and another to mark the way you bite together. The impressions will be given to the technician, along with any other information needed to make the crown. At this first appointment, a temporary crown made of plastic will be temporarily cemented. In two weeks, the new crown will be fitted and cemented over your prepared tooth.

Occasionally, if the tooth is severely damaged from decay or a broken filling, a root canal treatment may be indicated (see root canal therapy).