The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens.
One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 μm.
Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 μm for 10 N (n = 100), 173 μm for 20 N (n = 99), and 211 μm for 30 N (n = 93).
The mean displacement of 15-mm implants (16, 37, 51 μm) was significantly lower compared with 8.5-mm implants (103, 311, 396 μm) corresponding to 10, 20, and 30 N as lateral loads.Conclusions:
Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 μm and therefore results in a critical displacement.