Increased Fixation of Fluoride-modified Implants in Osteoporotic Rats

Objectives: It was of interest to study if the favorable biological response by fluoride-modified titanium implants as observed on normal bone tissue would show similar improved osseointegration on osteoporotic bone.

Methods: 24 female Wistar rats with an initial weight of 200-250g were included and divided into 2 groups, 12 SHAM and 12 ovariectomized rats. Eight weeks after ovariectomy, threaded titanium implants (TiO2 grit-blasted and TiO2 grit-blasted/HF-treated) were placed in the femoral distal metaphysis (one implant/leg) in SHAM and ovariectomized rats. Titanium screws (3.2mm length / 2.2mm diameter) were used. Two and four weeks after placement the rats were euthanized. Removal torque test was performed with a Lloyds LRX Materials testing machine fitted with a calibrated load-cell of 100 N. Cross-head speed range was set to 1.0 mm/min. Force measuring accuracy was 1%.

Results: Fluoride modified implants performed significantly better in ovariectomized animals than grit-blasted implants after 4 weeks of healing (p=0.03). Although there was a tendency to increased removal torque values from 2 to 4 weeks in all groups, only fluoride modified implants in the ovariectomized group were statistically significant (p=0.001). Moreover, no differences in the removal torque were found with fluoride-modified implants between control and ovariectomized animals at 4 weeks (p=0.41) while with grit-blasted implants the difference was highly significant (p= 0.005).

Conclusion: Implantation of fluoride-modified implants in rats gave similar bone healing/osseointegration in osteoporotic rats as in non-osteoporotic rats. The osseointegration as measured by removal torque test was significantly improved from 2 – 4 weeks healing time when fluoride-modified implants was placed into osteoporotic bone.