Dental Implants an Option for Replacing Missing Teeth

Unless you're in primary school, losing a tooth is an unwelcome event. As the name implies, permanent teeth don't spawn new teeth, so the options after losing a tooth to disease, decay or trauma are to leave the gaping space as is, or have a bridge or denture made - or go one step further and have a dental implant.

"Implants are really the gold standard when compared with bridges or dentures," says Mary Lou (Ma'Lou) C. Sabino, DDS, Assistant Professor of Oral and Maxillofacial Surgery, part of the Medical College of Wisconsin Department of Surgery. "They support and encourage bone retention under the gum, which neither bridges nor dentures can do."

Dental implants are titanium metal posts surgically placed in the bone under the gums. Over a healing period of several months, bone grows around the implant. The jawbone fuses to the implant and serves as a base for individual replacement of teeth, bridges or a denture. Once this foundation is in place, a crown to replace the original tooth is attached to the post. Like an ordinary crown placed over a fragment of a tooth whose root is still intact, the implant restoration feels and acts like a natural tooth.

The procedure of fusing bone to metal implants, called osseointegration, was developed approximately 50 years ago by a Swedish orthopedic surgeon, Per-Ingvar Branemark. The first dental implant was done in Europe in the mid-1960s, Dr. Sabino says, noting that the procedure was not introduced in the United States until some years later.

A Three-Step Procedure
Today, patients are having implants on a single tooth, multiple teeth or the entire mouth. Dental implants require three steps that typically call for about four appointments and take up to eight months, Dr. Sabino says.

"It's a three-step team approach. Typically, a patient's general dentist discusses options such as fixed or removable bridge, or an implant. If the patient chooses an implant, the dentist refers that patient to an oral surgeon or periodontist (a dentist specializing in surrounding structures and tissues of the gum) for evaluation. We analyze the patient's dentition, or tooth qualities, and determine if the patient has enough good bone structure, and is healthy enough to go through the implant procedure successfully."

Bone structure is critical, she says, because it must be wide enough and deep enough to accept the implant. Implants come in a variety of lengths and widths. What's most important is that the implant fits the space and can be placed deeply enough.

Step 1 involves placing a titanium post - the actual implant - into the bone under the gum. "It's a little like Woodworking 101," says Dr. Sabino. "You drill a hole in the bone, then screw the implant into the hole." Implants with screwlike threads are an advancement over the original implants, which were tapped into the bone, much like a hammer and nail, she says.

This stage includes a four-to-six-month waiting period to give the bone time to grow around the implant fixture. "Patient compliance is critical during this waiting period," Dr. Sabino says. According to the JADA patient guide: "Patients who want to have implants must commit to a meticulous oral hygiene routine, including flossing, brushing and regular dental visits to help protect the supporting tissues from any disease." The area is X-rayed to ensure that the implant is "hibernating" as it should. During this time, patients often wear a temporary tooth for cosmetic reasons, but it's not a tooth that can be used for biting or chewing.

Step 2 consists of the oral surgeon making an incision in the gum and inserting a small metal ball or temporary tooth to train the tissue to grow to the shape of a natural gum. This step usually requires a healing period of one or two weeks, Dr. Sabino says. In some instances, this can be done at the same time as Step 1.

Step 3 is placing the crown (the part of the tooth that's visible above the gum line). As with an ordinary dental crown, this crown is well-anchored by the implanted post that is firmly surrounded by bone, much the way a natural tooth's root stabilizes the tooth. A family dentist typically performs this step, Dr. Sabino says.

Highly Successful for Many Patients
In carefully selected patients, implants are successful 95% of the time, she says. But not every patient is a candidate for the dental implants. The JADA patient guide says: "Successful fusion of the bone to the implant requires good periodontal health. People at risk of experiencing gum disease - such as those with diabetes or those who smoke - might not be as good candidates."

"Patients must have a good healing process," Dr. Sabino says. "The nicotine smokers inhale often results in vasoconstriction, or reduced blood flow, and good blood flow is essential to healing." In addition to diabetics and smokers, patients who have undergone radiation therapy might also have reduced success rates with implants because their salivary glands don't function fully. Saliva has an antimicrobial action, she says.

Refinements and Adjunct Procedures
"I love implants," enthuses Dr. Sabino, who has placed many of them, primarily with patients at the Clement J. Zablocki VA Medical Center. "I love what they do for the patient, including patients with dentures." Patients who wear dentures find that the upper plate functions well, but the lower plate can slide out of place. "We can put two implants in the lower jaw and fix dentures in place so they don't move around."

Since implants were introduced, the technique has been continually refined over the years, including the widespread use of titanium as the preferred metal for the implant. "The body accepts titanium well," Dr. Sabino notes, "and it is very rigid."

In patients whose jawbone structure is inadequate in height or width for an implant, bone grafting can be done to build it up before the implant is placed. Some newer techniques are designed to shorten the time for the entire procedure, she says. But one step - the healing period after the implant is placed and before the crown is attached - shouldn't be shortened. "Healing takes time," she says, adding that younger patients tend to heal more quickly than their elders. "That's just biology."

Barbara Abel
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.