Abstract
Statistical analyses were made to work out the frequency of occurrence of unstable conditions (UST) in implant patients, cases, and implants themselves. The subjects and materials were 2,261 implant patients,2,969 cases, and 5,092 implants. UST was observed in 8.3% (185/2,226) of the patients, 8.6% (251/2,923) of the cases, and 7.3% (368/5,023) of the number of implants. About 45% of the patients with UST were found to have circular disease. The number of smokers with UST was larger than that of non-smokers with UST by 1.8%. The occurrence of UST in the implants placed into completely edentulous jaws was 5.0% less than in the implants placed into partially edentulous jaws. UST occurrence was less in removable supported implant prostheses, overdentures, single tooth implant crowns, and implant-implant supported prostheses, than in all the other types of prostheses. UST occurred less in screw and cylindrical type implants than in plate(blade) type implants, and less in HA-coating and TPS implants than in Ti implants. Regarding the length of the implants, UST appeared frequently in implants longer than 15 mm. However, the implant diameter and the presence or absence of GBR (guided bone regeneration) had nothing to do with the occurrence of UST. Implants placed into alveolar bone that was satisfactory in quality and quantity were less unstable. Gender had no bearing on UST whatever. Most of the implants were stable at the time of examination,but many implants developed UST over time as follow-up continued. These findings could be useful for a prospective clinical study taking stock of EBD (evidence-based dentistry).
