AN ANIMAL STUDY OF CP TITANIUM SCREWS WITH DIFFERENT SURFACE TOPOGRAPHIES

Sixty screw-shaped commercially pure (c.p.) titanium implants were ins erted in the tibial and the femoral metaphyses of adult rabbits. The i mplants were divided into four groups with different surface roughness es. The surface roughness was characterized before and after implant i nsertion. One group was left as-machined, this group had an initial R( a) value of 0.4 mu m. Two groups were blasted with 25 Cim sized partic les of TiO2 and Al2O3, respectively; corresponding Ra( )values for the se groups were 0.9 mu m and 0.8 mu m One group was blasted with 250 mu m sized particles of Al2O3 The R(a) value for this last group was 2.1 mu m. After a healing time of 12 weeks the torque necessary for impla nt removal and histomorphometric evaluations was evaluated. After remo val of the implants the R(a) values for the four above mentioned group s were 0.9, 1.3, 1.1 and 1.9 mu m, respectively. We found a better bon e response for implants blasted with 25 mu m sized particles compared to an as-machined (turned) surface, but no differences between the imp lants blasted with 25 mu m particles and the implants blasted with 250 mu m sized particles.