The behaviour of titanium as a biomaterial: microscopy study of plates and surrounding tissues in facial osteosynthesis.

Titanium has become the biomaterial of choice for facial osteosynthesis. Titanium is considered a highly biocompatible and corrosion resistant material, although the ultrastructural behaviour of titanium in human tissues after bone fixation is not well documented. A prospective scanning electron microscopy study was carried out on 37 commercially pure titanium miniplates which were removed from 23 patients who had undergone surgery for maxillofacial trauma or deformity. Twenty two cases were used as a control group. Implant-bone specimens were excised using tungsten burs and studied with a scanning electron microscope (Jeol JSM-T-300). Findings at the bone-titanium interface were analyzed, as well as the presence of contaminating bodies on the specimen surface. Biopsies were also obtained from the soft tissues adjacent to 20 miniplates, then sectioned and stained with Haematoxilin-Eosin for histological evaluation by light microscopy. The results showed good ultrastructural osseointegration of the osteosynthesis material in most cases (81.8%). Mobility was found upon removal in 80% of plates which showed clinical complications. A significant correlation was found between the degree of microscopical osseointegration and macroscopic fixation of the plate. Microscopical contamination was found in 100% of the nine plates with intraoral exposure, while only 36% of the 22 miniplates of the control group had contaminating elements (P < 0.001). Thirty-five point one percent of the plates showed hole-like substance loss images, whose size ranged from 10-25 mu. Light microscopy showed granular deposits in soft tissues surrounding the plates in 80% of the 20 specimens investigated. Our findings suggest a higher development of corrosion in titanium than previously reported. These findings are not correlated, however with the clinical complications.