Surface Modification of Dental Materials and Hard Tissues Using Nonthermal Atmospheric Plasma

Research of nonthermal atmospheric plasma (NTAP) for dental applications has been increasing in recent years. This paper presents a literature review of potential use of NTAP for treatment of surfaces of dental materials and hard dental tissues. The aim of NTAP interaction with dental materials and tissues is surface modification for stable and durable material-to-material or material-to-tissue bonds. Reactive particles in NTAP and various mixtures of gasses increase hydrophilicity of material surface, which is known to be hydrophobic in implants, ceramics or dental composites, with or without roughness changes. Adhesion of cells to implant surface was shown to improve after NTAP treatment, thereby promoting successful osseointegration. Bonding ceramic materials to the prepared surfaces of teeth or fiber/metal posts was shown to improve after NTAP treatment. Hard dental tissues achieve primarily micromechanical bonds with composite materials using dental adhesives. Increased organic content in the form of collagen fibrils and residual water pose a problem for achieving adequate and long-term adhesive-dentin bonds. This problem has not been solved with current adhesive application protocols. It was recently shown that application of NTAP improves the hydrophilicity of dentin surface and changes its polarity, which can contribute to better distribution of adhesive resin and deeper penetration into the hybrid layer. Previous studies pointed to similar or better initial adhesive bonds with dentin. However, adhesive-dentin bonds are subject to degradation in the long-term also after NTAP treatment suggesting the need for further optimization of NTAP for application on dentin.