Biofilm formation on restorative materials and resin composite cements

Objectives

Monolithic zirconia, polymer-infiltrated ceramic and acrylate polymer cemented with resin composite cement have recently been identified as prosthetic treatment options for zirconia implants. The aim of the present study is to determine in vitro, to what extent bacteria adhere to these materials.

Methods

Disks made of zirconia (Vita YZ YZ]), polymer-infiltrated ceramic (Vita Enamic VE]), acrylate polymer (Vita CAD-Temp CT]), self-adhesive cement (RelyX Unicem 2 Automix RUN]) and of two different adhesive cements (RelyX Ulimate RUL] and Vita Adiva F-Cem VAF]) were produced. The biofilm formation of three bacterial species (Streptococcus sanguinis, Fusobacterium nucleatum, Porphyromonas gingivalis) on each material was assessed over 72 h using a flow chamber system. The biofilms were quantified by crystal violet staining (optical density 595 nm) and visualized using SEM. The inorganic composition of the different materials was analyzed and the wettability of the specimens was measured.

Results

For the restorative materials lowest biofilm formation was found on CT: OD 0.5 ± 0.1, followed by VE: OD 0.8 ± 0.1 and YZ: OD 1.4 ± 0.3. The biofilm formation on resin composite cements was significantly lower on VAF: OD 0.6 ± 0.1 than for RUL: OD 0.9 ± 0.1 and RUN: OD 1.0 ± 0.1. A high wettability of the specimens with saliva/serum mixture tended to result in a higher biofilm formation. Correlations were obtained between the organic/inorganic composition of the materials and the polar/dispersive part of the surface free energy.

Significance

Three-species biofilm formation on restorative and cement materials strongly relies on the materials composition. If the restorative material CT and cement VAF also prevent excessive biofilm formation in a clinical situation should be further investigated.