Factors affecting implant mobility at placement and integration of mobile implants at uncovering

THIS STUDY EXAMINED 1) FACTORS that contributed to implant stability at pla cement and 2) the likelihood for an implant that was mobile at placement to osseointegrate. Eighty-one (3.1%) of 2,641 implants placed by the Dental I mplant Clinical Research Group between 1991 and 1995 were found to be mobil e at placement. Seventy-six (93.8%) of the 81 mobile implants were integrat ed at uncovering compared to 97.5% for the 2,560 immobile implants. Variabl es that influenced mobility at placement included patient age, implant desi gn and material, anterior-posterior jaw location, bone density, and use of a bone tap. Hydroxyapatite (HA)-coated implants were slightly more likely t o be mobile at placement (P = 0.324) than non-hydroxypatite (HA)coated impl ants. Of the 54 HA-coated implants that were mobile at placement, ail (100% ) integrated, while only 17 (81.5%) of the 22 mobile non-HA-coated implants integrated (P = 0.003). Mean electronic mobility testing device values (PT Vs) at uncovering for all implants mobile or immobile at placement that int egrated were -2.9 and -3.6 respectively. PTVs for HA-coated implants that w ere mobile (-3.5 PTV) or immobile (-4.0 PTV) at placement differed by 0.5 P TV, whereas non-HA-coated implants exhibited a greater difference of 1.2 PT Vs at uncovering. HA-coated implants, regardless of mobility at placement, integrated more frequently and exhibited greater stability than non HA-coat ed implants.