Effect of Disinfectants on Elastic Modulus, Flexural Strength and Color Stability of Denture Base Resins

Opportunistic and pathogenic microorganisms usually use the oral cavity as a reservoir. While routine dental practice, there might be a high risk of infection for all participants of dental treatment, including patients, providers, dental assistants and laboratory technicians. And the omission of a proper disinfection of dental prostheses might increase the risk for transmission of communicable diseases (e.g. Hepatitis B virus) and facultative pathogenic microorganisms.

Dentures are prosthetic devices constructed to replace missing teeth; they are supported by the surrounding soft and hard tissues of the oral cavity. The disinfection of dentures before and after contact with patients is theoretically an obligation to prevent transmission of infection.  However, there are no products available which are designed for the specific use of disinfecting dentures. The objective of this study was to investigate the impact of chemical disinfectants on elastic modulus, flexural strength and color stability of denture base resins. 

256 specimens from four acrylic denture base resins were manufactured. Two cold-curing denture base resins: PalaXpress (Heraeus Kulzer, Hanau, Germany), Futura Gen (Schuetz Dental, Roßbach, Germany) and two heat-curing denture base resins: Paladon 65 (Heraeus Kulzer, Hanau, Germany), FuturAcryl 2000 (Schuetz Dental, Roßbach, Germany) were used. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, Stammopur DR. Specimens were stored in distilled water and in chemical disinfecting agents. They were divided randomly into groups. E-Modulus and flexural strength were measured using the three-point bending test. Color changes (ΔE) were determined spectrophotometrically. 

The disinfection agents showed no significant influence on the E-modulus compared to distilled water (Acrylic vs. distilled water from (Futura Gen) 2688.80 ± 230.78 vs. 2766.60 ± 91.22 MPa to (PalaXpress) 3004.20 ± 26.40 vs. 2851.00 ± 95.23 MPa). Flexural strength after storage in distilled water and disinfection did not differ significantly (Acrylic vs. distilled water from (Paladon65) 27.28 ± 1.30 vs. 28.42 ± 0.84 N/mm², (p > 0.05) to (PalaXpress) 30.88 ± 0.25 vs. 29.68 ± 0.79 N/mm², p < 0.001). Disinfection caused a significant color change with Impresept of Paladon 65 (p ≤ 0.001), FuturaAcryl 2000 with Stammopur DR and D 050 Instru-Gen (p ≤ 0.001). 

In conclusion, the investigated disinfecting agents did not influence elastic modulus and flexural strength of the tested denture base resins negatively. Further studies should verify the impact of long term disinfection intervals on the material properties of acrylic denture base resins.

Article by Tobias Bensel, et al, from Germany.

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