The Effect of Plasma Treatment on Shear Bond Strength of High Impact Acrylic Resin Denture Base Lined with Two Types of Soft Lining Materials after Immersion in Distilled Water and Denture Cleanser

Abstract

Background: In dentistry, dentist takes the advantages of soft lining materials due to the viscoelastic properties. Themajor problem is the adhesion of the soft liner with the denture base material.Materials and Methods: Heat cured of high impact acrylic resin specimens prepared with dimensions 75x13x13mm forshear bond strength test, soft lining material (Refit and Mollosil) with a 3-mm thickness and used to join each twoacrylic blocks. Also four specimens with the same previous dimensions utilized for chemical and physical surfaceanalysis. The specimens grouped as control (without plasma) and experiment (with oxygen plasma) treated highimpact acrylic specimens.Results: Plasma treatment increased the shear bond strength for both Refit and Mollosil soft lining material afterimmersion in distilled water for 30 days as compared with the control group, also there was decrease in shear bondstrength for both Refit and Mollosil soft lining material of the experimental group after immersion in denture cleanserfor 30 days as compared with the control (without plasma treated) group. AFM analysis revealed that oxygenplasma treatment led to formation of (pits and protuberances) that increase the surface area and increase theshear bond between soft liners and high impact acrylic denture base.Conclusions: Oxygen plasma surface treatment was an effective method for increasing adhesion by physicaltopographic surface (due to the plasma etching process which in turn led to removal of some material from thesurface and this led to increase the bond strength).