Dental implants; the latest in false teeth

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After the dentist tells you the state of things in your mouth means the teeth you call your own will not be with you for long, wouldn't it be nice if he or she could just screw in replacements? There'd be no need for dentures-- no worrying about those tiny seeds the TV pitchman says are bound to become trapped behind a dental plate. No need to know about the holding power of dental adhesives or the special washes for false teeth that soak away all those stains the ads assure you are inevitable.

And there are millions of Americans who do endure the hassles of dentures. A 1985-1986 survey by the National Institute for Dental Research found that Americans 65 and older had lost an average of 10 teeth, and those 35 to 64 had an average of nine teeth missing. Four out of 10 (42 percent) of Americans 65 and older have lost all their teeth, as have 4 percent of those 35 to 65 years of age.

Ordinary dentures, generally made of plastic, are custom-fitted to match and adhere to the upper or lower jaw or made to clamp on to remaining teeth with metal supports or bridges.

But today there are dental implants, which add a method of attaching the denture with metal anchors directly and permanently to the jaw bone with no need to ever be removed by the wearer.

Dental scientists have discovered materials that will bond with bone and withstand the pressure created by biting and chewing. The bonding process is called "endosseous [within the bone] integration." Refined surgical techniques and follow-up have reduced the likelihood of the implant loosening, breaking, or being rejected by the body.

As many as 100,000 Americans will undergo surgery to be fitted with dental implants by 1992, according to a report of a June 1988 National Institutes of Health consensus development conference on dental implants. That compares with an estimated 24,500 implants done before 1985.

At least 10,000 dentists implant dental prostheses today, compared to 1,000 or so five years ago, the conference report stated. Dental implants are now being done at a rate of about 6,000 to 7,500 a year, adds Paul J. Mentag, a dentist and assistant professor of prosthodontics at the University of Detroit.

"We have the ability to functionally and aesthetically rehabilitate the oral invalid to a state of excellent dental health," says Paul H.J. Krogh, a Washington, D.C., oral and maxillofacial (jaw) surgeon and president of the Academy of Osseointegration, which represents 1,150 oral surgeons, other dental professionals, assistants, technicians, physicians and scientists.

"Not every patient is a candidate for implants," cautions the American Dental Association (ADA), headquartered in Chicago, which represents 146,000 dental professionals and students.

ADA points out there is no substitute for natural teeth, that implants will never function as well as the real thing. And the association's position is that implants are not suggested for cosmetic purposes alone.

"The best implant is a natural tooth," echoes Albert Guckes, a prosthodontic consultant at the dental clinic of the National Institute of Dental Research, Bethesda, Md. "With today's technology we can salvage badly damaged teeth, and that's the way to go," he says.

ADA says an individual's decision whether or not to have a dental implant should be made only after a careful examination and consultation with the person's dentist. A second professional opinion can add perspective.

If you are thinking of having dental implants, consider the following:

•  Determine if it is possible to save your own teeth.
•  Will you be able to keep the schedule required for implant surgery and follow-up? Some implants require many visits and a second stage of surgery. It may take as long as four to six months or more before the implant is completed.
•  Know what to expect in the way of pain, soreness, and possible long-term restrictions to your diet. You also may have to wear temporary devices.
•  Will you be able to follow special oral hygiene instructions and maintain a schedule of regular dental checkups that may go on for years?
•  Your body might reject the implant after a few months or a few years. Are you prepared to accept that possibility?
•  Medical risks are inherent in implant surgery, just as in any surgical procedure. In implant surgery, risks include sinus perforation, local and systemic infection, and paresthesias (abnormal or impaired skin sensation).

Dental implants are expensive. The cost of surgery, prosthesis, and associated professional services for a single implanted tooth is approximately $1,000 in Augusta, Ga., according to Ralph McKinney Jr., chairman of the department of oral pathology of the Medical College of Georgia in Augusta. In Washington, D.C., patients can expect to pay from $4,000 to $6,000 for a permanent lower bridge and up to $10,000 to $12,000 for a full fixed upper denture bridge or $18,000 to $24,000 for both upper and lower implants. Elsewhere, dentists and surgeons doing dental implants report that charges range up to $30,000.

Don't expect financial help from health or dental insurance plans. Since the implant devices are considered experimental by insurance companies, they will probably not be covered until they are proven effective, according to the Health Insurance Association of America.

Who are the people most skilled in doing this relatively new form of dental surgery? According to Phillip Worthington, M.D., professor of oral and maxillofacial surgery at the University of Washington in Seattle, 90 percent of American oral surgeons and approximately 40 percent of periodontists (specialists in gum disease) have done implants. The number of general practitioners and prosthodontists (specialists in bridges and dentures) who have done the procedure could not be determined.

Twenty thousand dentists have trained for implant work in the United States, Worthington's research determined. The scope of their training varies from having viewed instructional videotapes to having invested years in apprenticeship to others experienced in the procedure. The procedure is not regulated, and there are no accepted criteria for skill or experience that must be met to perform the procedure. ADA has not formally recognized implant surgery as a specialty.

D. Gregory Singleton, D.D.S., of FDA's Center for Devices and Radiological Health, in Silver Spring, Md., suggests talking with others who have had implants when making a decision about going to a particular dentist or oral surgeon.

Four general designs of devices are in use in implant dentistry today. The two most frequently used, according to Barry E. Sands, biomedical engineer at the Center for Devices and Radiological Health, are:

•  One-and two-stage cylindrical implants. These are inserted directly into holes drilled into the jawbone as sockets for screws to anchor a single false tooth, groups of false teeth, or entire rows of replacements. In two-stage implants, the cylinder is fitted into the bone and the gum is sutured closed over the device until the area heals and the device bonds to the bone around it. Then the surgical site is reopened to allow abutments to be placed in the cylinders, and the prosthesis is attached.
•  Blade types. Shaped to fit channels cut lengthwise into the jaw bone, blades have openings to accept bone regrowth through their framework. Tiered vanes above the gum line allow attachment of the prosthesis, which is generally done at the same time as the surgery.

The other types of devices--pin- and tooth-shaped--are less frequently implanted today and are generally used only for replacing individual teeth.

Most implant hardware in use today is made from titanium alloys. Coatings of calcium phosphates, carbon compounds, and titanium are sometimes added to promote successful bonding of the implant to bone. However, the coatings have not been shown to improve the bonding of the implant to bone, according to Sands.

Due to the routine presence of bacteria in the mouth, there is a risk of infection of the tissue or bone surrounding the implant. There also is some risk that the additional stress of the implant on bones in the jaw will speed up bone resorption and lead to implant failure and possibly a toothless future. Persistent pain or discomfort, speech problems, nerve injury, and damage to adjacent teeth are rare but possible complications of implants.

Conditions that can rule out dental implants include hypertension, heavy smoking, alcohol and drug abuse, chronic illnesses such as diabetes, bone deterioration, and bruxism (habitual tooth grinding), according to the University of Detroit's Dr. Mentag.

Endosseous implants are medical devices, regulated by FDA to ensure their safety and effectiveness. They are Class III devices, a category that covers life-supporting, life-sustaining, and implanted items. Under the 1976 Medical Device Amendments, FDA will require manufacturers of dental implants to submit data from controlled clinical studies to demonstrate the safety and effectiveness of their products or stop marketing them as early as 1990, according to FDA's Singleton.

FDA wants to know of problems consumers have with dental implants. "All the consumer needs to do is call the nearest FDA office and explain the nature of the problem. A report will get back to us. But we can't do anything until we hear about it," Sands says. Post-marketing surveillance is a way to detect and correct problems or remove a harmful or ineffective device from use as quickly as possible. (See "Looking for Trouble in Medical Devices," in the September 1987 issue of FDA Consumer.)

Dental implants have arrived. They may not be the solution for every case of tooth loss, but for those who are candidates, implants promise an alternative to dentures.