Anchorage of machined and TPS-coated dental implants of various lengths: An in vivo study in the dog maxilla

Background and objectives. The use of short implants is nowadays frequent in daily practice. The objective of this experimental study was to test the correlation between extremely different implant surfaces and the anchorage of short implants. Materials and Methods. The anchorage of machined-surface and titanium-plasma sprayed (TPS) implants of various lengths was investigated in the dog maxilla. Machinedsurface fixtures, 7 and 10 mm long, and TPS implants, 6 and 10 mm long, were reversetorqued after 3 months of healing. Results. Failure mode varied with the implant system used. For TPS implants, implant loosening coincided with the peak reverse-torque. The mean was 55.13 and 90.14 Ncm for the 6 mm and 10 mm long implants, respectively; the difference was statistically significant. For machined-surface implants, 2 torque values were measured, a mobilization and peak torque. Mobilization torque for the 7 and 10 mm fixtures was 19.50 and 22.12 Ncm, respectively. Peak torque was 29.63 and 39.25 Ncm, respectively; all differences were not statistically significant. The 6 mm TPS implants were more firmly anchored than the 7 and 10 mm machined-surface fixtures. The torque data measured in the maxilla were significantly lower than the data in the mandible, by half approximately. Discussion and Conclusion. In this experiment, parameters that influenced implant anchorage were: 1) the jaw bone quality (mandible vs. maxilla), 2) the implant surface and design, 3) implant length for TPS-coated implants. The present data suggest that treatment planning in terms of implant length selection and appropriate healing periods is implant system specific.