A soft denture lining material have been utilized in dentistry field for<br />more than one century. It is considered a kind of "shock absorber layer"<br />between a denture and the underlying oral mucosa, as it tending to absorb the mastication forces in addition to distributing it better than hard acrylic resins.<br />There are various criteria that must be met in order to utilize flexible<br />lining materials for complete dentures. Such as non-pliable thin atrophic<br />mucosa, excessive or irregular bone resorption, sharp alveolar ridge, bony protuberances exostosis or painful neurological points in edentulous patients, the patients who suffer from bruxism and xerostomia requires more specific ways for treatment with complete denture.<br />The soft lining materials were exposed to changes during function like<br />leaching out some components such as the plasticizer, over time it will lead to the alteration in the materials mechanical and physical properties in the patients' mouth. The leaching out of the plasticizer leads to changes in viscoelastic properties and loss of resilience of acrylic soft lining materials.Therefore, the soft lining materials become hard and lose their bonding strength properties .<br /><br />Bonding failure between the denture base and the lining material is<br />considered a major complication of utilizing these materials as it creates a surface encouraging, retaining bacterial and fungal growth, also plaque and calculus formation.<br />In order to avoid these drawbacks, many attempts are made to impregnate the filler agents within soft liner material like zirconium dioxide nanoparticles (ZrO2 )or Chitosan Nano powder, some plants extract like Aloe Vera, and Coconut Oil, or some chemicals like Chlorhexidine Diacetate in the form of salt .<br />