Factors related to Periotest values in endosseal implants: a 9-year follow-up

Periotest values (PTV) of successful endosseal implants of 2 one-stage implant systems. TPS and ITI, were followed from 3 months to 9 years in order to determine the factors that contribute to the values. 128 TPS screw implants were inserted in the lower jaw of 34 subjects, (mean age 55 years), for retaining overdentures. 108 ITI implants were inserted in the upper and lower jaws in 50 subjects (mean age 42 years), for retaining overdentures, crowns and bridges. PTVs were first measured after the osseointegration period and thereafter annually. First of all there was a difference between the 2 implant systems. Mean PTVs of TPS bicortical screws were significantly lower (P < 0.05) than those of ITI implants (screws, hollow-screws, hollow-cylinders). Factors which significantly contributed to PTVs of ITI implants were jaw (upper/lower), implant length and region of the jaw in which the implant was inserted. PTVs of ITI implants in the lower jaw were lower than in the upper jaw (P < 0.05). The length of implant had no effect on PTVs in the lower jaw, but in the upper jaw, PTVs of ITI 8-10-mm implants were lower than 12-mm implants (P < 0.05). PTVs of implants inserted in the anterior region of the upper jaw were higher than those in the posterior region (P < 0.05). In conclusion, bone quality and implant length had a statistically significant effect on implant mobility in long-term follow-up. PTVs of various implant systems, however, differ, a fact that must be taken into account in evaluating the success of implants.