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Crowns

Before Placing an Implant
Placing the Implants
Complications From Surgery
Implant Failure

When you get implants, more than one dental professional may treat you. An oral surgeon or a periodontist will place the implants in your jawbone. A prosthodontist or general dentist will make your crowns, bridges or dentures, which will look like natural teeth. The dental specialist who places your implants will coordinate your treatment with your general dentist or prosthodontist. He or she will decide what implants to use, how many you need and where they should be placed.

There are different types and manufacturers of implant devices. Therefore, the approach your dentists use may differ from the description presented here. The following describes the steps that a dentist typically takes when placing an implant.

Before Placing an Implant

Most people are good candidates to get dental implants. You must have enough bone in your jaw to allow an implant to be placed in the jawbone. You should be free of periodontal disease. Implants are not recommended for:

Smokers
People who have autoimmune diseases or take medicines used for these conditions
People who have had radiation therapy to the head and neck
People with uncontrolled diabetes

A dental professional will examine you and determine if you are suitable to get implants.

Some people want implants to replace teeth that have been missing for years. Others may need implants to replace teeth that were extracted recently because of severe decay, periodontal (gum) disease, infection or injury. In some cases, the teeth can be extracted and the implant placed at the same time. However, if you have a severe infection in a tooth root or your gums, your dentist may wait a few months after removing the teeth to allow the area to heal.

If you do not have enough bone to support an implant, you may be able to have the bone in the area built up. This is a common procedure called bone grafting or augmentation. If a bone graft is done, you will need 4 to 12 months to heal before having the implants placed in your jawbone. You can wear dentures or a bridge during this time, so you won't be without teeth.

Placing the Implants

Most implants are placed using a two-step process, although some newer implants can be placed in one step. What follows, is a description of how the two-step process works.

First surgery
You may be given antibiotics and pain medicine to take before the surgery. Your dentist will use local anesthesia for the procedure and will offer you sedation if you want it. You can be sedated by taking medicine by mouth, or through an intravenous line. This is a needle attached to a small tube placed in a vein in your arm.

See illustrations

Preparing the Tooth

After a Crown

A crown is a tooth-shaped cover placed over a tooth that is badly damaged or decayed. A crown is made to look like your tooth. Many people call it a cap.

Crowns may be placed for several reasons. Usually the tooth has been broken or damaged a great deal by decay. As a result, a filling can't replace enough of the tooth or make the tooth strong enough. A crown may hold together parts of a cracked tooth. It also can be used to hold a bridge in place. Crowns can be used to improve appearance as well. They may be placed to cover misshapen or badly discolored teeth.

Crowns can be made ahead of time (prefabricated) or made to order in a laboratory. Prefabricated crowns are made of plastic or stainless steel. They can be used on a temporary basis until a permanent crown is made.

Crowns can be all metal, porcelain fused to metal (PFM), or all ceramic. Metals include gold alloy, other alloys (palladium) or a base-metal alloy (nickel or chromium). The all-metal or PFM crowns are stronger and are better choices for back teeth than ceramic crowns. PFM and all-ceramic crowns are the same color as your natural teeth. They look just like normal teeth.

Crowns usually last at least seven years. In many cases they last much longer, up to 40 years or so.

Preparing the Tooth
If you need a crown, you may also need endodontic or root canal treatment on the tooth. Such treatment may be recommended if you have a lot of decay in the tooth or a risk of infection or injury to the tooth's pulp. Not everyone who needs a crown will also need a root canal.

Before placing a crown, your dentist may need to build up a foundation to support it. A foundation is needed if large areas of the tooth are decayed, damaged or missing. If you are receiving the crown after root canal treatment, your dentist may insert a post-and-core foundation.

To place a crown, your dentist will file down the tooth to make room for the crown. If you are receiving an all-metal crown, less of the tooth needs to be removed because these crowns can be made thinner than PFM or ceramic ones.

After filing down the tooth, your dentist will use a piece of thread or cord to push down the gum around the tooth. Then the dentist will make an impression (copy) of the tooth with a rubber-like material. The impression material sets in about five minutes. Then it is removed. Your dentist will also take an impression of the teeth above or below the tooth that will receive the crown. The purpose is to make sure the crown will fit into your normal bite.

The impressions are sent to the lab, where the crown is made. During that time, you will have a temporary crown placed. These crowns are usually made of plastic. They are made in advance by the laboratory or made by the dentist during your preparation visit. Then the dentist fits the temporary crown to your tooth.

These crowns are not meant to last for a long time. In some cases, however, a temporary crown can stay in place for a year or longer. If it needs to last longer, a lab-made plastic crown is best. It is stronger and will last longer than a temporary plastic crown that is made by the dentist.

Temporary cement is used to keep the crown in place. It is special cement that is designed to be weak. This allows your dentist to easily remove the temporary crown at each visit as your permanent crown is fitted.

At a second visit, your dentist will remove the temporary crown and test the permanent one. Sometimes crowns need additional polishing or glazing or some other adjustment before they are placed. Once the crown is ready, it's cemented to your tooth.

After a Crown
You shouldn't feel any discomfort or sensitivity after a crown is placed. However, if your tooth has not had a root canal it will still contain the nerve. You may therefore have some temporary sensitivity to heat and cold. If you notice pain or sensitivity when you bite down, contact your dentist. Usually this means that the crown is too high. This can be adjusted easily.

You may notice a thin, dark line next to the gumline on your crowned tooth if you look very closely in the mirror, particularly if you have a PFM crown. This dark line is the metal of the crown showing through and is normal.

A crowned tooth is protected from decay, except for the gum line. Your dentist may prescribe a high-fluoride gel for you to use every night to protect against decay. A crown does not protect against gum disease. You should continue practicing good oral hygiene.

Crowns, especially all-porcelain ones, can chip. This can sometimes be repaired in the mouth. Your dentist will etch the porcelain with acid and bond a composite resin to it to fix the chip. Porcelain repairs often don't last long. If there's a lot of chipping, you may need a replacement crown.

It's also possible that the cement could wash out from under the crown, but the crown does not fall out. Under these conditions, bacteria can leak in and cause decay. If your crown seems loose when you chew, or if you have an unusual odor around the tooth, discuss this with your dentist. Your dentist will check your crowns at your regular visits.

Crowns sometimes fall out. This can be caused by a lack of cement or an improper fit. If this happens, place the crown in a secure, zip-top plastic bag. Then bring it to your dentist to have it cemented back in place. If you are in no discomfort and your appearance is not affected, don't try to put the crown back in place yourself.

If you do need to put it back in your mouth, clean it well on the inside. Use a toothpick to loosen and remove any cement or debris that is stuck to the crown. A wet cotton swab can finish the cleaning. You can replace the crown temporarily using denture adhesive or temporary cement. This is sold in many pharmacies. Contact your dental office immediately and try to schedule a visit for the next day.

If you are away from home, seek a dentist in the area who can evaluate the problem. You may need a new crown or it may be possible to cement the old one back on the tooth.

11/25/2008