Bone regeneration into side openings and hollow inner channel of a dental implant

The current study examined whether bone can regenerate into an open space fabricated inside the metal implant and maintain its quantity and quality at the early post-implantation healing periods. 12 conventional one piece screw type titanium dental implants (control group) and 12 hybrid dental implants with spiral side openings (0.58 mm wide) connected to hollow inner channel (experimental group) were bilaterally placed in each quadrant at the P3, P4 and M1 positions in mandible of 4 adult beagles following 2 months of post-extraction healing. Fluorescent bone labels to qualitatively evaluate newly formed bone tissues were administered at 2 and 4 weeks of post-implantation periods, respectively. 3 control and 3 experimental bone-implant constructs for each animal were dissected from 2 animals at each 3 and 6 weeks of post-implantation healing periods. Undecalcified specimens were prepared from each construct for histological analyses to measure bone-to-implant contact (BIC) and interfacial bone area (BA), and also for nanoindentation and scanning electron microscopy to assess elastic modulus (E) and composition of bone tissues surrounding the implants, respectively. A substantial amount of newly formed bone tissues were observed at the implant interfaces of both implant groups. Bone tissues successfully regenerate through the side openings and hollow inner channel of the experimental implant as early as 3 weeks of post-implantation healing. The E values of the newly formed bone tissues were measured comparable to those of normal bone tissues. The current results indicate that the new hybrid implant can conduct bone regeneration into the inner architecture, which likely improves stability of the implant system by enhancing integrity of implant with interfacial bone.