An In-Vitro Evaluation of Alternative Disinfection Methods of Acrylic resin and Thermoplastic Resin Denture Base Materials

Abstract

Objectives: This study was designed to evaluate the antimicrobial effect of alternative disinfection methods of heat cured acrylic resin and thermoplastic resin denture base materials and to investigate the porosity resulting from disinfection by these methods. Material and Methods: Disc specimens of heat cured acrylic resin and thermoplastic resin were fabricated and divided into four groups for each denture base material according to the disinfection method. The specimens were contaminated in vitro by standardized suspensions of Candida albicans (C. albicans).The following test agents were used: distilled water (as a control group), 5% sodium hypochlorite (NaOCl), 100% white vinegar and 650 W microwave (MW) energy. After the disinfection procedure, the number of viable microbial cells was counted in CFU/ml. Porosities of acrylic resin and thermoplastic resin specimens were evaluated with Scanning Electron Microscope (SEM) after one month of daily exposure to disinfection. Results: ANOVA test showed that, there was a statistical significant difference among the tested treatment agents against C. albicans in each denture base material(P≤ 0.05). Post Hoc test showed a statistical significant difference between the control samples and the other disinfected samples in the microbial count, however, there was no statistical significant difference among the tested methods of disinfection (P>0.05).Regarding porosity area percentage, there was a statistical significant difference among the tested methods of disinfection (P≤ 0.05), where, 100% white vinegar showed the highest porosities followed by NaOCl then the MW disinfection and the least is the control group. Regarding comparison between the two denture base materials, thermoplastic resin showed statistically significant lower microbial adherence as well as lower porosity area percentage than heat cured acrylic resin(P≤ 0.05). Conclusion: All the tested disinfection methods shown to be efficient against C. albicans. Thermoplastic resin demonstrated lower microbial adherence than heat cured acrylic resin and lower porosity area percentages.

Flexural strength of three different denture base materials after immersion in a thyme extract and a chemical cleanser: An in vitro comparative study

“…Similar results were found by Robinson et al, who conducted a series of studies designed to investigate the effect of subjecting acrylic resin denture materials to denture cleanser at recommended and elevated level of cleanser concentrations. 17,25,26. The results corresponded with those of another study used polymides and PMMa as denture base materials, which found that immersion in 1% NaOCl resulted in a significant drop (p<0.05) in flexural strength 27 The reduction in strength was attributed by Pisani MX et al to the modification of the polymer resin chain by NaOCl. 28 Other studies, in contrast to ours, indicated no change in flexural strength (flexure strength above 65 MPa) with the use of NaOCl, possibly because the concentration of disinfectant, duration of immersion and type of acrylic resin were different from those in the present study.…”