Universal Journal of Materials Science 6(4): 115-118, 2018 http://www.hrpub.org DOI: 10.13189/ujms.2018.060401 Effect of Two Cleansing Agents on Water Sorption and Solubility of Two Thermoplastic Denture Base Materials Mahmoud Nabil Helaly 1,* , Ahmed Mohamed Alam-Eldein 2 , Ali Mohamed El-Sheikh 2 1 Department of Prosthesis, Faculty of Dentistry, October 6 University, Egypt 2 Department of Prosthesis, Faculty of Dentistry, Tanta University, Egypt Copyright©2018 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract Aim: Some patients experience adverse reactions to poly (methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented regarding water sorption and water solubility. The aim of this in vitro study was to evaluate the effect of two different cleansing agents on water sorption and solubility of two different thermoplastic denture base materials. Materials and methods: A total of 60 samples were fabricated from two different thermoplastic denture base materials (i.e. vertex thermosens and breflex). The samples were divided into 3 groups. Each group was including 20 samples, 10 samples from each denture base material. Samples of Group I were subjected to the distilled water as a control group. While samples of Group II were subjected to the Corega as a cleansing agent and samples of Group III were subjected to Fitty dent as the other cleansing agent. Effect of the two cleansing agents on the two-different thermoplastic denture base materials were evaluated and compared with regards water sorption and solubility. Results: Non-significant results were found regarding water sorption and solubility. The fittydent cleansing agent had a slight more non-significant effect on color stability of vertex thermosens and breflex denture base materials than corega cleansing agent and water. The corega and fittydent cleansing agents had a nonsignificant effect on water sorption and solubility of vertex thermosens and breflex denture base materials. Conclusion: Corega and fittydent cleansing agents could be used safely for disinfecting denture base materials (vertex thermosens and breflex) as they had non-significant effect on color stability, water sorbtion and solubility. Keywords Polyamide, Cleansing Agents, Water Sorption, Water Solubility 1. Introduction Many resins have been used for denture base construction. These materials include heat-activated (polymerized using a water bath or microwave oven), chemically activated (cold polymerized resins), and light-activated denture base acrylic resins. A cross-linking agent may also be added to the monomer component to improve its susceptibility to solvent crazing 1 . Nylon is a generic name for certain types of thermoplastic polymers known as polyamides. Nylon is a crystalline polymer. This crystalline nature lack of solubility in solvents, high heat resistance, and high strength coupled with ductility 2 . Water sorption and solubility causes dimensional instability, subjecting the material to internal stresses (by the molecules interred the structure of the material from water, cleansing agent etc.) that may result in crack formation which cause fractures of the denture (decrease strength of the material). Because water interacts with the polymer chains, it may lead to effective plasticization of the structure (as in acrylic resin), solvation or reversible rupture of weak inter-chain bonds, and irreversible disruption of the polymer matrix 3 . Water molecules spread between the macromolecules of the material, forcing them apart. This behavior affects dimensional behavior and denture stability; therefore, water sorption and solubility of these materials should be as low as possible 3 . Water sorption of a denture base resin may cause discoloration, halitosis which alters patient satisfaction. In other words, a higher water sorption rate tends to affect the material properties and consequently reduce the service life of a denture within the oral cavity; therefore, it is preferred to use materials with minimum possible water sorption rates 4,5 . Disinfection method should be effective without detrimental effects on the properties of materials used for fabrication of denture base. Everyday use of denture cleansers is recommended to prevent microbial colonization on denture and promote good oral health. Daily use of denture cleansers can affect the physical and mechanical properties of denture base material. In