Crestal remodelling and osseointegration at surface-modified commercially pure titanium and titanium alloy implants in a canine model

Background Ti-6Al-7Nb alloys exhibit enhanced mechanical properties and corrosion resistance and may represent an improvement to present commercially pure (CP) titanium oral implant technology. Objectives To evaluate crestal remodelling and osseointegration at CP titanium compared with Ti-6Al-7Nb alloy oral implants using a canine model. Methods Two threaded anodized CP titanium and two Ti-6Al-7Nb alloy anodized oral implants (phi 4.5 x 6.1 mm) were placed into each jaw quadrant in the edentulated posterior mandible in six adult male Hound Labrador mongrel dogs. Abutments were placed onto the implants, and the mucogingival flaps were adapted and sutured for transmucosal wound healing. Block biopsies were collected for histometric analysis following an 8-week healing interval. Results Healing was uneventful. Bone density outside and within the root of the threads averaged (+/- SE) 49.0 +/- 4.5% and 38.7 +/- 5.1% for CP titanium implants and 43.2 +/- 3.6% and 34.2 +/- 4.8% for Ti-6Al-7Nb alloy implants. Mean osseointegration reached 68.0 +/- 4.4% and 62.8 +/- 2.5% for CP titanium and Ti-6Al-7Nb alloy implants, respectively. Although crestal resorption at lingual sites averaged 0.2 +/- 0.1 mm for both technologies, crestal resorption at buccal sites averaged 0.9 +/- 0.2 and 1.0 +/- 0.6 mm for CP titanium and Ti-6Al-7Nb alloy implants, respectively. There were no statistically significant differences between implant technologies for any parameter assessed. Notably, advanced/advancing buccal crestal resorption exposing the implant threads was observed in 50% of the implants (four of six animals) regardless of implant technology; osteoclastic resorption still observed at 8 weeks following implant placement. Conclusion Within the limitations of study, anodized Ti-6Al-7Nb alloy implants may represent a feasible alternative to benchmark anodized CP titanium implants. Remodelling of the buccal crestal plate resulting in advanced bone loss appears a major impediment to oral implant osseointegration and possibly, in extension, implant maintenance.