A biphasic calcium phosphate coating for potential drug delivery affects early osseointegration of titanium implants

BACKGROUND: Calcium phosphate (CaP) surface coatings may accelerate osseointegration and serve as a drug delivery system for mineral-binding biomolecules. In a pilot study, the impact of a commercially available, thin CaP coating on early osseous bone remodeling was compared with a modern, subtractive-treated rough surface (SLA-like) in an animal trial. METHODS: In 16 rabbits, 32 endosseous implants (CaP; n = 16, SLA-like; n = 16) were bilaterally inserted in the proximal tibia after randomization. After 2 and 4 weeks, bone-implant contact (BIC;%) in the cortical (cBIC) and the trabecular bone (sBIC) as well as volume of bone within the screw thread with the highest amount of new-formed bone (area;%) were analyzed. RESULTS: After 2 weeks, cBIC was significantly higher for CaP when compared with SLA-like (58 ± 7% versus 40.4 ± 18%; P = 0.021). sBIC for CaP was 14.7 ± 8% and for SLA-like 7.2 ± 7.8% (P = 0.081). For area, the mean volumes were 82.8 ± 10.8% for CaP and 73.6 ± 22% for SLA-like (P = 0.311). After 4 weeks, cBIC was 42.9 ± 13% for the CaP and 46.5 ± 29.1% for the SLA-like group (P = 0.775). An sBIC of 6.9 ± 9.3% was calculated for CaP and of 12.3 ± 4.8% for SLA-like (P = 0.202). The values for area were 62.3 ± 24.1% for CaP and 50.1 ± 25.9% for SLA-like (P = 0.379). CONCLUSIONS: The CaP coating has putative additional advantages in the early osseoconduction phases. It seems suitable for a feasible and clinical applicable bioactivation.