Osseointegration and Histopathological Evaluation of Titanium–Titanium Diboride Composite Compared to Pure Titanium Implant Materials Prepared by Powder Metallurgy (In Vivo Study)

Abstract

The efficacy and osseointegration rate of an implant depend on its biocompatibility. Modern implantology seeks fast and reliable osseointegration, which is essential for clinical success. The objective of this research was to assess the osseointegration and biocompatibility of a titanium–titanium diboride composite (Ti-TiB₂) in rabbits in contrast to those of pure titanium (Ti). A total of 64 cylindrical implant specimens were fabricated, consisting of two sets: pure Ti (32 implants) and Ti-TiB₂ composite (32 implants). In this study, two implants were implanted per tibia (left and right tibias) in 16 white male New Zealand rabbits, for a total of four implants per rabbit (4 × 16 = 64 implants). A pushout test was used to assess implant specimen-bone bonding after 2 and 6 weeks of healing. The experiment utilized five rabbits per healing phase, which means that 20 implants per time point were used for the pushout tests. (10 for pure Ti and 10 for the composite). Histology was used to examine the tissue response to biocompatibility, and histomorphometry was used to measure new bone growth at the two time points. With three rabbits per time point, 12 implants were employed for the histological analyses. After implantation, the pushout shear strength results revealed that the mean shear strength of the Ti-TiB₂ implant specimens (5.4 ± 0.029 MPa for 2 weeks, 7.9 ± 0.029 MPa for 6 weeks) was statistically greater (p < 0.0001) than that of the pure Ti implant specimens (5.1 ± 0.015 MPa for 2 weeks, 6.6 ± 0.047 MPa for 6 weeks). After 2 weeks, woven bone tissues were observed around the pure titanium implants, and active osteoid tissue around the composite implants exhibited significant differences in new bone formation areas (NBFAs) (0.54 ± 0.004 mm² for Ti and 0.65 ± 0.003 mm² for the composite). After 6 weeks, there was new bone formation with osteocytes around the pure titanium implants (NBFA of 2.44 mm²) and osteoid maturation with the observation of reversal lines around the composite implants (NBFA of 2.89 mm²). The developed Ti-TiB₂ material was biocompatible and demonstrated superior bone growth compared to that of the pure Ti materials after 2 and 6 weeks.