Influence of surface roughness of barrier walls on guided bone augmentation: experimental study in rabbits

By using the guided tissue regeneration concept it is possible to augment bone, beyond the skeletal envelope, provided certain biologic, surgical, and barrier-related demands are met. Among barrier-related factors of importance are the surface properties.

The aim of this study was to evaluate whether different surface roughness of the barrier wall influences the amount and morphology of augmented bone in a secluded space, using a titanium cylinder as barrier device placed on the rabbit skull.

Cylinders of commercially pure titanium were fabricated by machining, using a turning tool. The inner cylinder wall was either left untreated or grit-blasted with titanium dioxide to increase surface roughness. The topographic profile of the inner surface of two cylinders (1 turned and 1 grit-blasted) was measured in vitro to achieve a numeric characterization of each type of surface topography. Two cylinders, one with grit-blasted and one with turned inner walls, were surgically placed and secured to the skull bone of each of eight rabbits. The plate of the cortical bone, facing the experimental area framed by the cylinder wall was removed, and care was taken to ensure total blood fill of the cylinders. After 3 months, the animals were sacrificed to obtain histology for histomorphometry.

The relative volume of augmented tissue in the grit-blasted cylinders (77.9 +/- 10.5%) did not differ significantly from that in the turned cylinders (73.4 +/- 5.5%, p = .118), neither did the volume of mineralized bone (20.1 +/- 8.2% vs. 22.1 +/- 7.2%, p = .064). The trabecular density of the augmented bone was higher close to the walls of both the turned and the grit-blasted cylinders compared to the overall trabecular density within the cylinders, but no significant difference between the two groups. However, the area of mineralized bone in direct contact with the inner surface of the titanium cylinder was significantly larger in the grit-blasted (33.9 +/- 13.3%) compared to the turned cylinders (12.0 +/- 8.5%, p = .01).

The use of titanium barriers with a grit-blasted inner surface compared to barriers with a turned surface resulted in the formation of similar amounts of bone beyond the skeletal envelope of the rabbit skull. However, a larger area of augmented mineralized bone was found in direct contact with the inner surface of the grit-blasted cylinders.