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

Prior research has shown that surface roughness influences cell behavior on dental restorations. However, the specific impact of polymer-infiltrated ceramic network (PICN) material surfaces on human gingival epithelial (HGE) cell growth remains unclear. Established studies suggest that smoother surfaces may promote better cell adhesion and proliferation. Yet, the exact threshold for optimal growth on PICN has not been clearly defined. This uncertainty motivates investigations into how surface roughness affects HGE cells. No prior work had resolved whether PICN surfaces could support exponential growth. The need for precise data on surface roughness thresholds is evident. This gap motivated a focused study on PICN material and epithelial cell interactions.

The aim of this study was to evaluate how different surface roughness levels of PICN material influence the growth of HGE cells in vitro. Specifically, the researchers sought to determine whether surface roughness could serve as a threshold for exponential cell growth. The study focused on comparing two polishing methods for PICN material. The goal was to identify the optimal surface roughness for epithelial cell proliferation. The researchers also aimed to assess whether the manufacturer's polishing method could achieve a suitable surface. The study aimed to clarify the relationship between surface roughness and cell density. The researchers hypothesized that smoother surfaces would promote better growth. The study sought to provide evidence for clinical applications of PICN restorations.

The study used primary human gingival epithelial cells cultured on PICN material specimens. Specimens were polished with either silica carbide paper or manufacturer-approved wheels. Surface roughness was quantified using R_a values. Cell growth was monitored over 1, 3, and 6 days. Tissue culture plastic served as a reference control. Non-linear regression models were applied to analyze growth patterns. Exponential growth and decay models were compared to fit the data. The researchers evaluated how R_a values correlated with cell density.

HGE cell growth on tissue culture plastic followed an exponential model (R² = 0.966). On PICN material, growth decreased as surface roughness increased. An exponential decay model fit the PICN data (R² = 0.666). A threshold R_a of 0.254 μm was identified as the upper limit for exponential growth. Growth was highest when R_a was below 0.127 μm. The manufacturer’s polishing method produced R_a values of 0.118 μm or lower. Smoother surfaces (R_a < 0.254 μm) supported better cell growth than rougher ones. The results suggest a strong inverse relationship between surface roughness and cell proliferation.

The study found that smoother PICN surfaces promote exponential growth of HGE cells. The threshold R_a value of 0.254 μm marks the upper limit for optimal growth. The manufacturer’s polishing method achieved surfaces below this threshold. These findings suggest that polishing PICN material to a smooth finish is beneficial. The results contrast with prior research on implant components, which showed different trends. The authors propose that smoother restorative surfaces may improve peri-implant soft tissue health. The data highlight the importance of surface roughness in cell behavior. The researchers suggest that clinical use of PICN material should prioritize smooth polishing.