Osseointegration of titanium alloy and HA-coated implants in healthy and ovariectomized animals: a histomorphometric study

Objectives: The objective of the present study is to evaluate the response to dental implants in healthy and osteoporotic bone.
Materials and methods: Ten ovariectomized (OVX) New Zealand rabbits submitted to a hypocalcic diet and 10 sham-aged rabbits were used. All animals were submitted to bone mineral density (BMD) measurements before ovariectomy, and also 4 months afterwards, using dual energy X-ray absorptiometry. The BMD measurements showed a significant loss of bone mass, between the first and second examinations, only in the experimental group ( P <0.05). After the bone mass loss induction period, three different implants were installed in the proximal tibia metaphisis of each animal: a titanium alloy implant (Ti), a plasma-spray hydroxyapatite-coated implant (HA-PS), and another implant coated with hydroxyapatite with the biomimetic process (HA-B).
Results: After 3 months, histomorphometry showed a bone-to-implant contact (BIC) for Ti implants of 73.09±13.74% in healthy and 66.09±30.01% in OVX animals. The BIC for the HA-PS was 64.83±15.65% and 90.17±8.14% for healthy and OVX animals, respectively, and 88.66±5.30% and 87.96±10.71% for the HA-B implants placed in the same conditions. The differences between the implants in healthy and OVX conditions were not statistically significant ( P >0.05). The only significant difference within groups was observed in the healthy animals between HA-B and Ti implants ( P <0.06).
Conclusion: Within the parameters used in this animal model it was not possible to observe BIC differences between osteoporotic and healthy animals.