Bioadhesion on Textured Interfaces in the Human Oral Cavity—An In Situ Study

Abstract

Extensive biofilm formation on materials used in restorative dentistry is a common reason for their failure and the development of oral diseases like peri-implantitis or secondary caries. Therefore, novel materials and strategies that result in reduced biofouling capacities are urgently sought. Previous research suggests that surface structures in the range of bacterial cell sizes seem to be a promising approach to modulate bacterial adhesion and biofilm formation. Here we investigated bioadhesion within the oral cavity on a low surface energy material (perfluorpolyether) with different texture types (line-, hole-, pillar-like), feature sizes in a range from 0.7–4.5 µm and graded distances (0.7–130.5 µm). As a model system, the materials were fixed on splints and exposed to the oral cavity. We analyzed the enzymatic activity of amylase and lysozyme, pellicle formation, and bacterial colonization after 8 h intraoral exposure. In opposite to in vitro experiments, these in situ experiments revealed no clear signs of altered bacterial surface colonization regarding structure dimensions and texture types compared to unstructured substrates or natural enamel. In part, there seemed to be a decreasing trend of adherent cells with increasing periodicities and structure sizes, but this pattern was weak and irregular. Pellicle formation took place on all substrates in an unaltered manner. However, pellicle formation was most pronounced within recessed areas thereby partially masking the three-dimensional character of the surfaces. As the natural pellicle layer is obviously the most dominant prerequisite for bacterial adhesion, colonization in the oral environment cannot be easily controlled by structural means.

Biphasic Textures Reducing Bacterial Surface Colonization in the Human Oral Cavity

“…In a previous study, microstructured surfaces with line‐, bump‐, and hole‐like geometries and various dimensions fabricated with imprint lithography made of hydrophobic perfluoropolyether were tested for their low‐fouling properties in the oral cavity. [ 42 ] However, these 3D structures had no significant impact on bacterial colonization compared to plain surfaces. Therefore, this study tested partially smaller structures composed of PMMA and silicon, namely, Type I samples (Figure 1).…”

“…This was a pilot study with specimens applied buccaly (facing the cheek) in line with many previous studies. [42,51,52] Pellicles on buccal sites are thicker than on palatal surfaces, [53] and initial bacterial colonization is also more pronounced. Therefore, bioadhesion on palatal and other sites will be evaluated in future studies.…”

“…[ 34–41 ] Unfortunately, these strategies were shown to fail in the oral environment, even for short‐term tests of a few hours. [ 42 ]…”

“…[34][35][36][37][38][39][40][41] Unfortunately, these strategies were shown to fail in the oral environment, even for short-term tests of a few hours. [42] A previous study demonstrated how nanocomposites with a low surface energy (18-20 J m À2 ) could reduce bacterial surface colonization in the oral cavity and lead to accelerated bacterial removal. [43] Based on this observation, we systematically evaluated a related strategy to inhibit bacterial colonization by plain, that is, unstructured, surfaces exhibiting chemical biphasic textures.…”

Interaction between microorganisms and dental material surfaces: general concepts and research progress

“…Developing restorative materials that are not conducive to microbial adhesion and colonization is the goal of contemporary dental materials science. The development of new resin composites and adhesive systems prolongs the release of antibacterial agents [ 23–27 ]; however, biofilm formation also depends on the surface characteristics of these materials [ 28 , 29 ]. Therefore, fine-tuning the physical and chemical properties of resin composites can prevent biofilm formation, laying a solid foundation for developing new resins.…”