Human Gingival Epithelial Growth In Vitro on a Polymer-Infiltrated Ceramic Network Restorative Material.

Abstract

To investigate the growth of primary human gingival epithelial (HGE) cells on polymer-infiltrated ceramic network (PICN) material (Vita Enamic) with different surface roughnesses. PICN material specimens were polished with either silica carbide paper (grit-polished) or the manufacturer's polishing wheels (wheel-polished), and the surface roughness (Ra ) measured. HGE cells were seeded and grown for 1, 3, or 6 days. Growth on tissue culture plastic was used as a control. Non-linear regression analysis was used to examine the effect of surface roughness on cell growth. HGE cell growth on tissue culture plastic fitted an exponential growth model over the 6-day experimental period (R2 = 0.966). Through day 6, cell density on PICN decreased with increasing surface roughness, with a fit to an exponential decay model (R2 = 0.666). A threshold Ra value of 0.254 μm (95% CI 0.177-0.332) was determined as an upper limit for exponential growth. Cell growth was greatest on the group of specimens with Ra value below 0.127μm. Specimens polished by the manufacturer's method produced surface roughness of 0.118 μm and below. PICN material polished to a smooth surface (Ra < 0.254 μm) resulted in exponential growth of HGE cell growth compared to rough surfaces. Polishing PICN material as smooth as possible (below a Ra of 0.127 μm) was found to maximize epithelial cell growth on the PICN material surface. The manufacturer's polishing method achieved a sufficiently smooth surface. These results are contrary to previous research regarding surface roughness of transgingival implant restoration components. The study results suggest that smoother restorative material surfaces could improve peri-implant soft tissue health.