June 20, 1997 By Connie Daughtry
GAINESVILLE, Fla.---Denture wearers who fear their new false teeth will slip and slide may have reason to smile.
A five-year study of a dental implant material developed at the University of Florida shows it successfully prevents bone loss after tooth extraction.
Jaw bone deterioration can alter facial structure, enabling some denture wearers to touch their nose with their tongue and giving them the appearance of cartoon characters Andy Gump or Popeye. Dentures also can dislodge. The problem forces many to have their dentures repeatedly relined or even replaced.
Bone loss is most rapid in the first six to 24 months after tooth extraction. In the first five years, the typical person will lose almost three-eighths of an inch from each jaw.
But when a slender, translucent cone-shaped implant made of Bioglass is implanted in the jaw, bone loss is slowed or prevented, said Harold Stanley, professor emeritus of oral and maxillofacial pathology and oncology at UF's College of Dentistry and head of the Bioglass implant study.
"Of the more than 20 million people in the United States who wear complete dentures, 70 percent say they are dissatisfied with them, especially the lower denture," Stanley said. "Bioglass could be the substance that could make them happier. It is cheaper than alternative materials, stays in place long-term and contains natural body products."
Bioglass was invented 28 years ago by former UF materials engineer Professor Larry Hench. The implants, smaller than a dime, range from 4 to 12 mm in length and are inserted into newly emptied tooth sockets. Bioglass implants bond to living bone through a reaction between a chemical substance on their surface and body fluids. Currently, the material appears to have the capacity for the fastest rate of bone and soft tissue bonding of known bioactive materials.
More than 20 years ago, UF researchers first used Bioglass in baboons. Their initial strategy was to replace the whole tooth with Bioglass, but the tooth crowns immediately broke off. The Bioglass implant roots, however, remained in place, and bone began reforming on their surfaces. This discovery led to using Bioglass as root replacements in humans in 1983.
Researchers were able to track 20 of 29 original patients for more than five years. The total number of implants: 168. To date, only 14.3 percent of the implants have come out of the socket and 7.7 percent required grinding down of the implant as they rose to the surface of the gum. Only 1 percent requiring grinding down, came out. The Bioglass retention rate is 86 percent after five years.
Other implant studies using materials such as acrylic resin and calcium phosphate have not proven as successful. Implant losses have been reported between 8 to 55 percent with only 30 months of follow-up. "The overall clinical outcome of UF's Bioglass implant study, with an average of more than 85 percent of the implants being retained long-term, is significantly more favorable than results of previous investigations of other implant materials intended for the same type application," said Jack E. Lemons, director of laboratory surgical research and professor of biomaterials and surgery at the University of Alabama at Birmingham.
Bioglass appears to have potential widespread use in dental research.
"The bottom line for this research is to improve the quality of life for people who have lost their teeth," said co-researcher A.E. Buddy Clark, professor of prothosdontics and associate dean of the UF dental college. "When using Bioglass, future denture wearers can avoid many dental problems."
The UF study can be found in the February issue of International Journal of Oral and Maxillofacial Implants.
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