This study aimed to compare two different implant surface treatments of the implant system Bi-Implant (Plan 1 Health): one surface sandblasted with hydroxyapatite (HA) (Osseogrip®) and one machined surface. Histomorphologic and histomorphometric evaluations of the bone healing at the interface between a titanium implant and bone were performed using a light microscopic technique. Twenty-four commercially pure titanium implants with a smooth surface and 24 implants with a sandblasted surface were inserted in the tibias of 12 rabbits. The 12 rabbits were divided into three groups, each consisting of four animals, were sacrificed at 4 weeks (I group), 8 weeks (II group) and 12 weeks (III group) after the insertion of the biomaterial. The results emphasized that in the sections examined with the light microscope, the bone was in intimate contact with the implant surface and the bone surrounding the implants was mostly lamellar. After 4 weeks, mature bone tightly surrounding some areas of the implant perimeter was observed. The implant with the Osseogrip® surface showed an average percentage of bone-implant contact (%BIC) equal to 33%, while the one with the machined surface showed a %BIC equal to 17%. After 8 weeks, a progressive increase in mineralized bone surrounding the implant surface was detected, making the results of the machined surface superposable to the Osseogrip® surface results (48 and 44%). After 12 weeks, the implants with the machined surface exhibited close contact with the bone tissue corresponding to 62% of their perimeter, while for the implants with the Osseogrip® surface the surface contact was 67% of the implant surface. The morphometric evaluation of %BIC at the three time points evidenced an increase in bone-titanium contact over time on both machined and Osseogrip® surfaces. Moreover, implants with rough surfaces demonstrated better behavior than the implants with the machined surface when taking into account the earlier osteointegration (4 weeks) of the pen-implantar tissues.
