Understanding the Influence of Modified Surfaces on Early Dynamics of Osseointegration by Histomorphometric Analysis: An In Vivo Study

Rapid osseointegration remains a topic of interest in implant dentistry; however, the effects of modified surfaces during the early stages of osseointegration are not entirely elucidated. With that purpose, this study aimed to critically investigate early osseointegration parameters in cortical and trabecular bone through histological analysis in a preclinical model, and to assess the impact of a hydrophilic implant surface modification on the early peri-implant bone characteristics changes. Hydrophilic micro-texturized (HMT) and machined Ti (MT) implants were developed and their physical-chemical properties were characterized. A total of 48 implants were placed in the distal femoral epiphysis in rats. The implants were retrieved for histological and histomorphometric analyses after 6, 14, or 28 days. Physicochemical characterization showed significant differences with regard to morphology, roughness, and wettability of the developed HMT and MT implants. Bone to implant contact (BIC) values were significantly higher for HMT implants (test) compared with MT implants (control), both in cortical bone and trabecular bone at 14 and 28 days. BIC was significantly higher from 6 to 14 days in the test group, suggesting a time range when the modified implant surface exerts an influence over osseointegration and bone maturation. In conclusion, HMT implants significantly increased BIC values earlier than MT implants. A significant improvement in osseointegration parameters was present from 6 to 14 days for the modified surface, which reflects to the earlier period of time that hydrophilic rougher surface modification affects osseointegration process. Further studies are needed to correlate these histological findings with molecular and mechanical data.