RETRIEVAL STUDY OF STAINLESS-STEEL AND TITANIUM MINIPLATES AND SCREWSUSED IN MAXILLOFACIAL SURGERY

The surfaces of 43 stainless steel miniplates and 19 titanium miniplat es with matching screws of the same materials were studied after retri eval with respect to surface degradation. Stereomicroscopic and scanni ng electron microscopic (SEM) examinations were performed, and surface roughness and hardness of the plates were measured. Defects of mechan ical nature which could be traced back to handling procedures were fou nd in all stainless steel and titanium devices. Metal tongues and spli nters were occasionally found associated with screw threads and in the periphery of plate screw holes. Corrosion defects were observed in ab out 1/5 of the stainless steel plates, restricted to the countersink a rea. Corrosion defects were also found on the chamfer of the underside of stainless steel screw heads. None of the titanium devices showed e vidence of corrosion. The surface roughness of the titanium plates was higher than for the stainless steel plates. The retrieved plates were rougher than the new plates.