Abstract
It is postulated that biofilm formation in the oral cavity causes some oral diseases. Lactoferrin is an antibacterial protein in saliva and an important defense factor against biofilm development. We analyzed the adsorbed amount of lactoferrin and the dissociation constant (K d) of lactoferrin to the surface of different dental materials using an equilibrium analysis technique in a 27 MHz quartz crystal microbalance (QCM) measurement. Four different materials, titanium (Ti), stainless steel (SUS), zirconia (ZrO2) and polymethyl methacrylate (PMMA), were evaluated. These materials were coated onto QCM sensors and the surfaces characterized by atomic force microscopic observation, measurements of surface roughness, contact angles of water, and zeta potential. QCM measurements revealed that Ti and SUS showed a greater amount of lactoferrin adsorption than ZrO2 and PMMA. Surface roughness and zeta potential influenced the lactoferrin adsorption. On the contrary, the K d value analysis indicated that the adsorbed lactoferrin bound less tightly to the Ti and SUS surfaces than to the ZrO2 and PMMA surfaces. The hydrophobic interaction between lactoferrin and ZrO2 and PMMA is presumed to participate in better binding of lactoferrin to ZrO2 and PMMA surfaces. It was revealed that lactoferrin adsorption behavior was influenced by the characteristics of the material surface.
Highlights
It is postulated that biofilm formation in the oral cavity causes oral diseases such as dental caries, periodontal diseases, denture-induced stomatitis, and peri-implantitis [1]
Spherical particles with a diameter of 0.2∼0.3 μm were observed, while a wave-like structure was observed on the surface of polymethyl methacrylate (PMMA)
The apparent zeta potential of Ti was significantly lower than those of the others, while that of ZrO2 was significantly higher compared to the others (Table 4)
Summary
It is postulated that biofilm formation in the oral cavity causes oral diseases such as dental caries, periodontal diseases, denture-induced stomatitis, and peri-implantitis [1]. Biofilm includes a complex of attached bacterial and salivary macromolecules and forms on the teeth and mucosal surface and the surface of metal or ceramic prostheses, orthodontic brackets, resin restoratives, and titanium implants [2, 3]. Lactoferrin in saliva represents an important defense factor against bacterial injuries including bacterial growth, biofilm development, iron overload, reactive oxygen formation, and inflammatory processes. The first function attributed to the antibacterial activity of lactoferrin was to bind iron, which is necessary for bacterial growth and survival [5]. Some have tried to modify the surface of dental materials by applying a lactoferrin coating. NaganoTakebe et al reported that a lactoferrin coating on a titanium surface inhibited bacterial adhesion and exhibited bactericidal effects [7]. Lactoferrin adsorbed to contact lenses (polyHEMA or silicone hydrogel) had previously been shown to kill Gram-negative bacteria [8]
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