In Vitro investigation of surface roughness and biofilm formation on different restorative materials stored in food-simulating solutions

Aim: The aim of this study is to analyze the surface roughness and biofilm formation parameters of different restorative materials immersed in that food-simulating liquid, and to evaluate the relationship between these parameters. Materials and Methods: A total of 220 samples made from five restorative materials (alkasit giomer, ormocer, direct composite, and indirect composite) were divided into groups and immersed in food-simulating solutions (heptane, ethanol, citric acid and saliva [control]) for 7 days. Initial and final surface roughness values were measured, followed by bacterial adhesion testing after sterilization using the colony-forming unit (cfu) method. Scanning electron microscopy (SEM) was used to examine 20 pre-selected samples after the bacterial adhesion test. Results: Cention N and Beautifil II showed higher surface roughness, while Gradia Plus had lower roughness (p<0.001). Citric acid affected surface roughness more than other solutions, and heptane had the least impact (p<0.001). Cention N and Beautifil II had higher bacterial retention, while G-aenial A'Chord and Gradia Plus showed lower adhesion (p=0.008). Citric acid led to the highest microbial retention, while heptane showed the lowest (p<0.001). Conclusion: Materials with different properties were affected to varying degrees by the solutions. The alkasit and giomer samples were more affected than the other samples, and citric acid was found to have a significant impact on the surface. In our study, it was observed that surface roughness influenced microbial retention on restorative materials; however, it is important to note that other factors, such as surface charge, surface energy, and material composition, also play a critical role in bacterial adhesion. Keywords: bacterial adhesion, composite, surface roughness.