Plasma treatment effects on resin-based tooth restoration improvements
Abstract
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The dental restoration is the recovery of the function, integrity and morphology of missing tooth structure using dental restorative materials. Recent years, safety and aesthetic concerns have increasingly driven dental restorations from using metallic to resin composite materials. However, resin composite restorations displayed a prohibitively failure rate, especially after longevity tests. High failure rates necessitate frequent replacements which lead to increased loss of sound tooth structure and more complicated subsequent restorations. To elongate the lifetime of composite restorations, novel methods are highly required. The non-thermal plasma technique has been applied in the dental restoration. Plasma treatment exhibits outstanding effects on dental substrates modifications. However, the resin-tooth (enamel, dentin) bonding interface performance needs to be evaluated. This study focuses on the evaluation of plasma treatment on dental bonding strength improving. Different dental substrates, including enamel, dentin and dental ceramic were employed in this study. The plasma treatment exhibited enhancement effects on resin-enamel, resin-dentin, and resin-ceramic bonding under a range of plasma operating conditions. Micro-tensile and micro-shear bonding strength tests were conducted to evaluate the plasma treatment effects on the bonding strength. SEM measurement was also applied to exam the bonding cross-section and fracture surface morphology. To further explore the mechanism of bonding enhancement, the dental substrates surface chemistries information was scanned by FTIR and ATR-FTIR facilities. From our results, plasma treatment consistently increased the resin-enamel, resin-dentin, and resin-ceramic bonding strengths, while the underlying mechanisms of bonding improvements were complex. First, plasma treatment increased the dental substrates wettability and improved the adhesive resin infiltrations. Second, plasma treatment improved the monomer (e.g. HEMA, GDMP etc.) grafting on tooth substrates and enhanced the monomer bonding to dental substrate at bonding interface. In additional, the plasma treatment could induce adhesive resin polymerization and obtained more durable adhesive layers. Regarding to ceramic bonding, plasma treatment improved the distribution of silane coupling agents coating on zirconia ceramic surface, which lead to tighter resin-ceramic bonds. In conclusion, non-thermal atmospheric plasma treatment is a very effective method in both direct and indirect restoration performance. The experimental results settled the fundamentals of the plasma techniques application in dentistry.
Degree
Ph. D.
Thesis Department
Rights
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