Implant-supported overdentures, a prevention of bone loss in edentulous mandibles? A 5-year follow-up study

The purposes of this study were to analyse 1) the changes in the bone miner al content (BMC) in mandibles with implant-supported overdentures when comp ared with the physiologic age-related mandibular BMC loss, 2) whether the B MC changes were different in groups without or with a bar connecting the im plants and 3) whether the presence of mandibular osteoporosis affects the l oss of bone height around the implants. The material consisted of 22 long-t erm edentulous healthy persons, 18 women and 4 men from 54 to 78 years of a ge with 1 Astra Tech Dental Implant in both canine regions, connected by a bar in half of the patients. BMC measurements were performed in vivo by dua l-photon scanner at baseline, just after attachment insertion, at 2-year an d 5-year visits. Mandibular osteoporosis was estimated by comparing baselin e BMC values with normal mandibular BMC values for young adults of same gen der. Loss of bone height around implants was measured on periodically ident ical intraoral radiographs. The fixed parts of the implant-system were stab le during the trial in all patients. In conclusion: I)the increased functio n after this treatment seems to cause a load-related bone formation which m inimizes the physiologic age-related mandibular BMC loss, 2) this effect se ems to be independent of attachment system and 3) mandibular osteoporosis p rior to implant treatment may be a risk factor for bone loss around implant s. However, this treatment can be recommended also in osteoporotic persons.