Porous titanium granules promote bone healing and growth in rabbit tibia peri-implant osseous defects

The aim of this study was to investigate the osteoconductive properties and biological performance of porous titanium granules used in osseous defects adjacent to titanium implants.

In this animal experimental study, calibrated defects were prepared in the tibias of 24 New Zealand rabbits. The defects were randomized into two tests and one control group. The test defects were grafted with either metallic or oxidized porous titanium granules (PTG or WPTG, respectively), whereas control defects were left empty (sham). The defects were closed with a submerged coin shaped titanium implant. Defects were left for healing for 4 weeks. After healing, the implants were removed and the new bone tissue formed onto the implant surface was analyzed for run x 2, osteocalcin, collagen-I, tartrate-resistant acid phosphatase, H(+)-ATPase, tumor necrosis factor-alpha, interleukin (IL)-6 and IL-10 gene expression using reverse transcriptase polymerase chain reaction. Wound fluid from the healed defects was analyzed for lactate dehydrogenase and alkaline phosphatase activity. Finally osteoconductivity was analyzed by micro-computed tomography and histology.

Significantly more new bone formed in PTG and WPTG grafted defects compared with sham. The new bone grew both through the porosities of the granules and onto the implant surfaces. The WPTG group showed significantly less expression of key inflammation markers, but with no significant difference in a marker for necrosis. The WPTG also showed a significant increase in collagen-I mRNA expression compared with PTG.

The results suggest that PTG and WPTG are both osteoconductive materials that can be used to promote bone formation in osseous defects adjacent to titanium implants without hampering implant osseointegration.