Results gained from current research topics at the Department of Operative Dentistry and Periodontology will be discussed. The presentation focuses on the influence of dietary changes on the microbial composition of oral biofilm, the eradication of initial and mature oral biofilm using antimicrobial photodynamic therapy (aPDT) with visible light (vis) and water-filtered Infrared-A (wIRA), and prevention of biomaterial-associated infections by spin-coating of material surfaces  with synthetic mimics of antimicrobial peptides (SMAMPs). In the first part of the presentation, the microbial community of oral biofilm was analyzed using Illumina MiSeq sequencing. It could be shown that frequent consumption of sucrose led to changes in the microbiota of the oral biofilm. An increase of non-mutans streptococci was revealed, supporting the extended ecological plaque hypothesis. In the second part of the presentation, aPDT using vis+wIRA in combination with chlorine e6 or toluidine blue showed high killing effects in situ on the initial and mature oral biofilm. Hence this technique could be helpful in the treatment of peri-implantitis and periodontitis, particularly due to the additional healing effects of wIRA on human tissue. In the final part of the presentation the potential of poly(oxonorbornene)-based SMAMPs for clinical applications was shown. The compounds were tested in solution using standard methods. In addition, SMAMPs were used to spine-coat silicon wafers to deliver an antimicrobial biomaterial surface which was evaluated using a new airborne assay.