Introduction:
Removable prosthetic restorations are most often made of PMMA due to the low cost of the material. In addition to PMMA, acetal is one of the newer materials that has been used in prosthetics. The use of prosthetic restorations involves not only proper oral hygiene, but also the hygiene of the dentures.

Aim of the study:
To assess the impact of a denture hygiene tablet solution on the mechanical and physicochemical properties of both PMMA and acetal used to make dentures.

Material and methods:
The acrylic material Vertex Rapid Simplified and the self-polymerizing Vertex Castavaria from Dentimex B.V. (Netherlands) and acetal material Acetal Dental from Pressing Dental (Republic of San Marino) were used for the tests. The samples were immersed in distilled water from KAMIX (Poland) and an aqueous solution of denture Hygiene Active Cleaning Tablets Protefix (Germany). The immersion time was 5475 min., which corresponds to stimulated five years. Following immersion, the following tests were performer: hardness, impact and three-point bending strength and sorption.

Results:
The polymer materials used showed a decrease in hardness after immersion in an aqueous solution of denture hygiene tablets. In the case of cold polymerizing PMMA, the impact strength value also decreases. Acetal samples following immersion in the aqueous solution demonstrate a lower value of notched impact strength. After immersion in the tablet solution, a decrease in bending strength is also observed in the case of hot and cold polymerized PMMA, while the acetal material shows an increase in three-point bending strength.

Conclusions:
Denture hygiene tablet solution Protefix has a negative effect on the hardness of hot-polymerizing PMMA, cold-polymerizing PMMA or acetal resin. Additionally, the threepoint bending strength of acrylic materials deteriorates.