Interface between titanium miniplate/screw and human calvaria.

This study demonstrates interfacial changes of titanium miniplate/screw with normal calvaria and nonvascularized calvarial bone graft ensued from craniectomy in a 53-year-old female. In 18 months after operation, a right parietal bone containing an L-shaped miniplate with screws, 5 mm long and 2 mm in external diameter, was harvested, fixed, and embedded in methylmetacrylate. Fifteen micrometer thick sections were made by an EXAKT cutting-grinding system (Exakt Company, Hamburg, Germany), and reviewed under the bright field light microscope. The mean of the bone-contacting surface ratio (BCSR) in six screwed bone was 64.1%; 69.3% in normal bone, and 60.4% in grafted bone. The trabecular bone areas in 10 x 5 mm (50 mm2) rectangular area of diploe surrounding the screws was 43.02 mm2; 45.25 mm2 in normal calvaria; and 41.82 mm2 in grafted bone. The mean Ca/P peak-height ratio of the plated and screwed calvaria was 1.47 in a 9 mm wide zone around each screw; 1.37 in normal calvaria; and 1.51 in grafted calvaria. We concede that the effect of direct contact of titanium with screws onto the bone is as much as an osseous integration (osseointegration).