Bone-derived titanium coating improves in vivo implant osseointegration in an experimental animal model

Coating of orthopaedic or dental Titanium (Ti) implants with extracellular bone matrix components (e.g., Type I collagen or hydroxyapatite) is usually performed to enhance their osseointegration. Aim of the present research is the evaluation of an innovative bone-derived Ti coating, containing bone apatite and Type I bone collagen preserved, in an experimental model. Coated and uncoated titanium implants were inserted into the extra-articular bone of the distal femur of twelve New Zealand White Rabbits. Labelling of bone formation was performed by sequential intraperitoneal administration of three stains. After 45 and 90 days animals were sacrificed. Bone specimens were embedded in a glycol methacrylate resin and sectioned along a plane parallel to the long axis of the implants for histomorphometric, scanning electron microscopy and energy dispersive X-ray analyses. Bone implant contact (BIC), trabecular thickness (Tb.Th) and calcium-phosphorus ratio were measured. Data were subjected to nonparametric Wilcoxon rank-sum test and Student's t test. All implants healed without adverse reactions. After 45 days from implant, significant (p < 0.05) differences in BIC (55.6 ± 17.1% vs. 29.2 ± 20.1%) and Tb.Th (108.7 ± 67.1 µm vs. 66.6 ± 48.6 µm) were observed between coated and uncoated implants. Significant (p < 0.05) differences in BIC (61.3 ± 2.1% vs. 35.7 ± 16.4%) and Tb.Th (211.4 ± 80.8 µm vs. 150.9 ± 61.5 µm) between coated and uncoated implants were also detected after 90 days. No differences were measured in calcium-phosphorous ratio. Our data indicate that Ti integration can be enhanced by the proposed surface coating. This could accelerate stable implant fixation and early or immediate loading of the device.