Bacterial Adhesion on Dental Polymers as a Function of Manufacturing Techniques

Area of Science:

• Biomaterials Science
• Dental Materials
• Microbiology

Background:

• Microbiological behavior of dental polymers is critical for the clinical success of dental restorations.
• Manufacturing processes and machining significantly influence the surface properties and bacterial adhesion of dental materials.

Purpose of the Study:

• To investigate bacterial adhesion on various dental polymers based on manufacturing techniques (additive/subtractive) and polishing protocols.
• To correlate surface properties like roughness and surface-free energy with bacterial adhesion.

Main Methods:

• Specimens of polyaryletherketone (PEEK, PEKK, AKP), resin-based CAD/CAM materials (composite, PMMA), and methacrylate (MA)-based materials were fabricated.
• Surface roughness (Rz, Ra) and surface-free energy (SFE) were measured.
• In vitro biofilm formation using Streptococcus mutans and Streptococcus sanguinis was assessed after salivary pellicle formation, with bacterial quantification via fluorometric assay.

Main Results:

• Manufacturing method and polishing significantly influenced bacterial adhesion for both S. mutans and S. sanguinis (p < 0.001).
• Enhanced polishing significantly reduced bacterial adhesion (S. sanguinis: PC = -0.240; S. mutans: PC = -0.206).
• A significant correlation was found between S. sanguinis adhesion and surface roughness Rz (p = 0.010, PC = 0.135). Vertically printed MA specimens and pressed PEEK showed higher bacterial adhesion.

Conclusions:

• Fabrication methods play a critical role in bacterial adhesion, with pressed PEEK showing the highest initial accumulation.
• Horizontal Digital Light Processing (DLP) fabrication reduced bacterial adhesion.
• Achieving a surface roughness below 10 µm and effective polishing are essential for minimizing bacterial adhesion on dental polymers.