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.