Titanium Substratum Roughness as a Determinant of Human Gingival Fibroblast Fibronectin and alpha-Smooth Muscle Actin Expression

The most appropriate surface treatment to enhance gingival connective tissue formation on the abutment of dental implants remains undefined, with healing associated with a scar-like response. We have previously shown that topographies with an arithmetic average of the absolute profile height deviations (R-a) = 4.0 induces an anti-fibrotic phenotype in human gingival fibroblasts (HGFs) by causing nascent adhesion formation. With bacterial colonization considerations, we hypothesized that a lower R-a could be identified that would alter adhesion stability and promote a matrix remodeling phenotype. Focal adhesions (FAs) area decreased with increasing roughness, although no differences in cell attachment or proliferation were observed. Alpha smooth muscle actin (alpha-SMA) protein levels were significantly reduced on R-a = 3.0 and 4.0 vs. 0.1 (p < 0.05), with incorporation of alpha-SMA into stress fibers most prominent on R-a = 0.1. Fibronectin protein levels were reduced on 3.0 and 4.0 vs. 0.1 (p < 0.05), and R-a = 1.5 and deeper significantly altered fibronectin deposition. Addition of exogenous TGF-beta 3 increased HGF adhesion size on 0.1 surfaces, but not on any other topography. We conclude that R-a = 1.5 is sufficient to reduce adhesion size and inhibit alpha-SMA incorporation into stress fibers in HGFs, but 3.0 is required in the presence of exogenous TGF-beta 3. Our findings have implications for inhibiting fibrotic tissue formation surrounding percutaneous devices such as dental implants.