Dentures contain cytotoxic chemicals, e.g., benzoic acid, formaldehyde, methacrylate, methyl methacrylate, etc.

Soaking dentures in warm water tends to reduce their toxicity.

Pre-soaking dentures for a week in warm water before wearing them is the highest choice.

M. Ebrahimi Saravi, M. Vojdami, & F. Bahrani (“Evaluation of Cellular Toxicity of Three Denture Base Acrylic Resins,” Journal of Dentistry of Tehran University of Medical Sciences, Autumn, 2012) wrote …

“All the tested resins induced some degree of toxicity. Cytotoxicity of Futura Gen, GC Reline Hard and Meliodent resins failed to show any significant reduction from 24 hours to one week. Thus it is recommended to immerse the dentures for 24 hours prior to delivery to the patient.”

Gottfried Schmalz & Dorthe Arenholt-Bindslev (Biocompatibility of Dental Materials, 2009) wrote …

“It has been well known since the beginning of the 1970s from in vitro and in vivo observation that PMMA acrylics and, particularly, permanent soft relining materials may promote the growth of various fungi and bacteria such as Candida albicans and other Candida species, Escherichia coli, and Pseudomonas aeruginosa. In addition, MMA, phthalate, and the cross-linking substance may stimulate microbial proliferation. But ‘microclefts’ between permanent soft relining materials and the ‘hard’ denture base may stimulate microbial growth, too. This was corroborated by clinical studies on patients wearing dentures with a permanent soft relining. It was found that up to 85% of these patients suffered from oral fungi identifiable by culture techniques. An inflamed mucosa was clearly correlated with these microorganisms. Colonization of permanent soft reliners was significantly enhanced by the salivary denture pellicle or serum components. In this context it was observed that proliferation of fungi (Candida ssp.) was closely associated with poor denture hygiene.”
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