The conversion of monomers to polymers is incomplete in the polymerization of denture base resins. Some unreacted methyl methacrylate monomers remain in the denture base. Methacrylic acid, formaldehyde, benzoic acid, phthalic acid, benzoic acid phenyl ester, dicyclohexyl phthalate, polybutylene succinate, phenyl salicylate, and benzoyl peroxide can be detected in the soaking liquid of denture base resins. Methyl methacrylate and its derivatives affect the membrane integrity and cellular function of primary cells, such as gingival fibroblasts, pulp cells, and periodontal ligament cells. They likewise affect the expression of glutathione, cytokines, and growth factors. The degree of methyl methacrylate polymerization directly affects the surface hardness, finish, flexure strength, deflection, fatigue resistance, wear resistance, and dimensional and color stability of the material and further accelerates the degradation effect of certain enzymes in saliva to the polymer and microbes breeding on the surface of the denture base. Different methods, such as increasing the polymer powder-liquid ratio, soaking the denture base in water, extending the polymerization period, increasing the temperature of the polymerization cycle, subjecting the resins to heating treatment after polymerization, adding polyethylene fibers or crosslinking agents, polishing the surface, utilizing a ultraviolet-activated coating material, and appropriately adjusting the activator quality concentrations, can be implemented to reduce the level of residual methyl methacrylate.
