Non-thermal atmospheric plasmas in dental restoration: Improved resin adhesive penetration

Abstract

Objective To investigate the influence of non-thermal plasma treatment on the penetration of a model dental adhesive into the demineralized dentin. Methods Prepared dentin surfaces were conditioned with Scotchbond Universal etchant for 15 s and sectioned equally perpendicular to the etched surfaces. The separated halves were randomly selected for treatment with an argon plasma brush (input current 6 mA, treatment time 30 s) or gentle argon air blowing (treatment time 30 s, as control). The plasma-treated specimens and control specimens were applied with a model adhesive containing 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (BisGMA) and 2-hydroxyethyl methacrylate (HEMA) (mass ratio of 30/70), gently air-dried for 5 s, and light-cured for 20 s. Cross-sectional specimens were characterized using micro-Raman spectral mapping across the dentin, adhesive/dentin interface, and adhesive layer at 1∼micron spatial resolution. SEM was also employed to examine the adhesive/dentin interfacial morphology. Results The micro-Raman result disclosed that plasma treatment significantly improved the penetration of the adhesive, evidenced by the apparently higher content of the adhesive at the adhesive/dentin interface as compared to the control. Specifically, the improvement of the adhesive penetration using plasma technique was achieved by dramatically enhancing the penetration of hydrophilic monomer (HEMA), while maintaining the penetration of hydrophobic monomer (BisGMA). Morphological observation at the adhesive/dentin interface using SEM also confirmed the improved adhesive penetration. The results further suggested that plasma treatment could benefit polymerization of the adhesive, especially in the interface region. Conclusion The significant role of the non-thermal plasma brush in improving the adhesive penetration into demineralized dentin has been demonstrated. The results obtained may offer a better prospect of using plasma in dental restoration to optimize adhesion between tooth substrate and restorative materials.

Effect of non‐thermal atmospheric plasma on the dentin‐surface topography and composition and on the bond strength of a universal adhesive

“…However, the cohesive failure modes also increased after aging, corroborating the findings of the present study for the direct water exposure storage protocol. Previous studies have reported that NTAP treatment of dentin before application of etch‐and‐rinse adhesive increased the μ TBS , supporting the findings of the present investigation for the simulated pulpal pressure‐aging protocol.…”

Nonthermal Atmospheric Plasmas in Dental Restoration

“…Scanning electron microscope images (Fig. 4c, d) also showed that resin tags were longer and more tortuous with lateral projections (Han et al 2014;Zhang et al 2014), reflecting an enhanced penetration of resin into dentin tubules and tubule branches thanks to more hydrophilic tubule walls as a result of NTAP treatment. The results were consistent with the notion (mentioned in the Dental Surface Modification section) that NTAP could increase the hydrophilicity/wettability of dentin collagen or substrates, which caused the preferential infiltration of hydrophilic components.…”

Remineralizing effect of cold plasma and/or bioglass on demineralized enamel

“…Their results indicated that cold plasmas were effective in deactivating oral bacteria in culture after 5 min of application, this might play some roles in prevention or treatment of dental caries. It was also found that the cold plasma treatment improved primer infiltration compared to a control 12) . One study revealed that atmospheric-pressure plasmas increased the surface energy and surface wettability of enamel, and as a result its bond strength with sealants, potentially serving as a substitute for conventional acid etching procedures or as an adjunct to self-etch sealants 13) .…”