Permanent dental implantation was successful 98 percent of the time in a study at the Mayo Clinic, and doctors called the implants a safe and effective alternative to conventional dentures.

The two-year study involved 70 patients, in whom a total of 358 of the titanium fixtures were implanted.

Implantation of the devices involves drilling four to six holes into the jaw and inserting tubes into the holes. Over the next three to six months, "osseointegration" occurs; that is, the bone grows into the tube's threads, and the fixtures, in essence, become part of the jaw. At this point, permanent dentures can be attached.

The best candidates for the procedure, according to the current Mayo Clinic Proceedings, are:

*people with physical problems making it impossible to wear regular dentures; and

*people who cannot wear dentures for psychological reasons.

Implants are more successful for lower teeth than for upper teeth. Patients also must have enough bone mass to accept the implants, doctors said.

The technique was developed in Sweden in 1965. In 1982, 25 teams of U.S. surgeons were taught how to perform implants, and the Mayo study is the first report of results in this country.

Complications, mostly delayed healing, were described as "minimal and easily resolved." Even in the few cases where an implant didn't take, other implants were used to hold the dentures, the study said.

Implants cost $5,000 to $8,000 per jaw and are covered by most insurance plans except Medicare, the clinic said.