Effect of intermittent loading and surface roughness on peri-implant bone formation in a bone chamber model

Both implant surface characteristics and mechanical loading are known to affect implant osseointegration. Their interaction and the underlying mechanisms by which they affect peri-implant healing processes are still unknown. The aim of this study is therefore to investigate the influence of a turned versus a rough (Plus), Dentsply Friadent) implant surface on peri-implant bone formation in case of unloaded or loaded implant healing.

Bone formation was evaluated around screw-shaped implants under four experimental conditions using a repeated sampling bone chamber methodology: (1) unloaded turned implant (CU), (2) unloaded implant with a rough surface (TU), (3) loaded turned implant (CL), and (4) loaded implant with a rough surface (TL). Peri-implant tissue samples were paraffin embedded after implant removal and examined histologically and histomorphometrically. A mixed model was used for statistical analysis.

The surface of bone tissue relative to the total tissue area (bone area fraction) was not affected by the experimental conditions. The areas of bone trabeculae relative to the bone area (bone fraction) were significantly higher for TL compared with CU and TU. The bone fraction in the vicinity (100 microm zone) of the implant (BFZ) was significantly the highest around the loaded roughened implants (TL).

Implant loading did not affect bone formation in the absence of surface roughness, and implant surface roughness had no effect in the absence of loading. However, a bone-stimulating effect in the implant's vicinity was assigned to the rough surface when the implant was loaded.