Advanced co-culture model: Soft tissue cell and bacteria interactions at the transgingival dental implant interface.

Abstract

To better simulate and understand the clinical situation in which tissue cells and bacteria compete for settlement on an implant surface, the aim was to develop an improved transgingival co-culture model. For this model human gingival fibroblasts (HGF) were seeded on different titanium surfaces in the presence of the early colonizer Streptococcus gordonii or mixed oral bacteria. Subsequently adhesion and viability of HGF cells was analyzed. Simultaneous co-culture showed no decrease in the viability of HGF cells at early stages compared to the control group. However, a moderate impact on HGF viability (76±23%) was observed after 4h of co-culture, which then significantly decreased after 5h (21±2%) of co-cultivation, resulting in cell death and detachment from the surface. Further experiments including saliva pre-treatment of smooth and structured titanium surfaces with Streptococcus gordonii or mixed oral bacteria suggested a cell-protective property of saliva. Our study revealed that during simultaneous co-culture of cells and bacteria, which resembles the clinical situation the closest, the viability of gingival cells is considerably high in the early phase, suggesting that increasing initial cell adhesion rather than antibacterial functionality is a major goal and a relevant aspect in the development and testing of transgingival implant and abutment surface modifications.