Purpose: To evaluate the effects of coarse microcavities added to micron and submicron rough implant surfaces in the implant-bone anchorage in rabbits.

Materials and methods: Confocal interferometry was used to quantify roughness. Electron microscopy and energy-dispersive x-rays characterized the surfaces prior to and after implantation. X-ray photoelectron spectroscopy and contact angle determined the surface chemistry and energy, respectively. Fifteen New Zealand White rabbits received, respectively, one cavity-less (C-) and one cavity-rich (C+) implant per femoral condyle and were allowed to integrate for 2 and 8 weeks. The bone-to-implant contact (BIC), bone volume density (BVD), and removal torque (RTQ) were then analyzed.

Results: The cavities produced on the surfaces were 48.4 ± 16.8 μm in diameter and 37.8 ± 36.5 μm deep (5.9% ± 1.1% surface coverage). C+ did not alter the surface chemistry or energy. In vivo, C+ implants produced more BIC and RTQ at 8 weeks (P = .002 and P = .059, respectively) and more BVD at 2 and 8 weeks postimplantation (P = .031 and P = .078, respectively). Bone tissue was observed inside the cavities of C+ both histologically and by scanning electron microscopy after implant removal.

Conclusion: Unevenly distributed coarse cavities within a micron and submicron rough surface allow bone ingrowth and increase implant stability and bone-surface unions in rabbits. These results encourage the design of implants with multilevel surface topographies to improve implant-based regeneration.