Background: Bacterial biofilms adhere to all tissues and surfaces in the oral cavity. Oral biofilms are responsible for the decay of human dental structures and the inflammatory degeneration of the alveolar bone. Moreover, oral biofilms on artificial materials influence the lifespan of dental prostheses and restoratives. Methods: To investigate in vivo oral biofilm formation and growth, five different dental restorative materials were analyzed and compared to human enamel. The roughness of the materials and the human enamel control probe were measured at the start of the study. The dental restorative materials and the human enamel control probe were placed in dental splints and worn for 3 h, 24 h and 72 h. Results: Scanning electron microscopy (SEM) revealed major differences between oral biofilm formation and growth on the materials compared to those on human enamel. Microbiological analyses showed that bacterial strains differed between the materials. Significant differences were observed in the roughness of the dental materials. Conclusions: It can be concluded that material roughness affects biofilm formation on dental surfaces and restoratives, but other factors, such as surface charge, surface energy and material composition, may also have an influence.

Bacterial biofilms adhere to all oral surfaces and may alter or degrade them. For investigations of the oral biofilm, growing on new restorative dental biomaterials, sterilized dental enamel surfaces as natural, control, and reference materials are used. A novel method for disinfection and sterilization of surfaces is low-pressure plasma (LPP) sterilization, which is a nondestructive and nontoxic technology. The roughness of the dental enamel surface was determined before and after LPP sterilization. Enamel discs were placed in dental splints and worn for five days in vivo. Oral biofilm was fixed for scanning electron microscopy (SEM). Biofilms growing in vitro were characterized microbiologically before and after sterilization and examined by confocal laser scanning microscopy (CLSM). Microbiology demonstrated that various bacterial strains were present in the biofilms. SEM showed multiple layers of densely packed bacteria, and CLSM demonstrated that the biofilm contained live and dead bacteria. After LPP sterilization, no biofilm could be detected, and the enamel surface remained unaltered. It may be concluded that LPP sterilization is an effective, nondestructive method for disinfection of enamel before application in the oral cavity. LPP sterilization may be suitable for sterilization of dental materials without altering their surfaces.

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