Attachment, spreading, and matrix formation by human gingival fibroblasts on porous-structured titanium alloy and calcium polyphosphate substrates.

Porous calcium polyphosphate (CPP) structures represent promising resorbable implant systems that can promote anchorage to connective tissues. Previous studies focused on chondrocyte interactions with CPP, but there are limited data on interactions of soft connective tissue cells with these materials. We studied attachment, spreading, and matrix formation by human gingival fibroblasts when cultured on amorphous and crystalline CPP. Comparison with porous Ti6Al4V substrates of similar volume percent, porosity, and pore size distribution provided evaluations of fibroblast interactions with rapid, moderate, and nonbiodegradable systems, respectively. Cells were incubated on substrates in medium containing ascorbic acid and evaluated at 3, 24, 48, 72, and 96 h after plating. Attached cell counts, cytoplasmic actin filament area, and immunostained extracellular type 1 collagen or fibronectin were quantified by morphometric analyses using epifluorescence microscopy. Cell morphology and substrate interactions were evaluated by scanning electron microscopy. Spreading, attachment, and matrix production were similar for both CPP substrates. In contrast, titanium alloy substrates exhibited threefold more attachment and twofold more spreading than CPP substrates. The area per cell of immunostained extracellular collagen and fibronectin was similar for the three different substrates. The results indicate that the crystallinity and, hence, degradation rate of CPP substrates does not substantially affect the interactions of fibroblasts with CPP materials but that compared with titanium alloy substrates, spreading and attachment are inhibited.