Histomorphological and Histomorphometric Analyses of Grade IV Commercially Pure Titanium and Grade v Ti-6Al-4V Titanium Alloy Implant Substrates: An in Vivo Study in Dogs

Purpose: To evaluate the bone response to grade IV commercially pure titanium (G4) relative to Ti-6Al-4V (G5). Materials and Methods: Implant surface topography was characterized by optical interferometry and scanning electron microscopy (SEM). Thirty-six implants (Signo Vinces, n 18 per group) were installed in the radius of 18 dogs. The animals were killed at 1, 3, and 6 weeks, resulting in 6 implants per group and time in vivo for bone morphology, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO) evaluation. Results: SEM depicted a more uniform topography of G4 than G5. Surfaces were statistically homogeneous for Sa, Sq, and Sdr. At 1 week, new bone formation was observed within the healing connective tissue in contact with the implant surface. At 3 weeks, new bone in direct contact with the implant surface was observed at all bone regions. At 6 weeks, the healing chambers filled with woven bone depicted an onset of replacement by lamellar bone. No significant effect of substrate was detected. Time presented an effect on BIC and BAFO (P < 0.001). Conclusion: Both titanium substrates were biocompatible and osseoconductive at the bone tissue level.