Control of microbial contamination with commercially available cleaning solutions

Use of Photosensitizer, Glutaraldehyde, alcohol and Ultrasonics in disinfection of polished and rough surfaces of self-curing polymethyl methacrylate denture base material

AIM

To assess the effectiveness of chemical, ultrasonic and photodynamic therapy (PDT) mediated disinfection against in-vitro biofilms colonized with C. albicans, S. oralis, and S. aureus on surfaces of PMMA (polymethylmethacrylate) denture base material.

MATERIALS AND METHODS

Fifty plates of PMMA were prepared with two different surface topography (rough and polished) analyzed by profilometry. Provenance culture (ATCC) of C. albicans, S. oralis, and S. aureus were inoculated on specimens and exposed to disinfection. The disinfection included Rosebengal (RB) 5 μM activated by a red LED, 2% glutaraldehyde, 70% Isopropyl alcohol, ultrasonic disinfection, and saline solution as a control. The antimicrobial efficacy was assessed by subsequently calculating viable counts after disinfection. The data were analyzed using analysis of variance (ANOVA) and Tukey's Post Hoc test.

RESULTS

The unpolished surface demonstrated the highest average surface roughness As 5.32±0.36 (μm) and root mean square roughness Rr 7.22±0.81 (μm) compared to the polished surface. Intergroup comparison demonstrated polished and rough PMMA plate disinfected with rose bengal, glutaraldehyde and alcohol-based disinfection exhibited comparable reduction against C. albicans and S. oralis CFU/mL (log10) (p>0.05). Whereas, this reduction was significantly higher on the rough and polished surface of PMMA when disinfected using ultrasounds for 30 sec (p<0.05). Rose Bengal was the most effective method of disinfection against S. aureus both on polished (0.17±0.13) and rough (0.44±0.22) denture plates (p<0.05).

CONCLUSION

The ultrasonic disinfection was most effective in reducing viable microbial counts. RB mediated PDT exhibited a more substantial reduction of the colonies of S.aureus.

The effect of disinfecting solutions on bending properties and weight changes of Co-Cr and Ti-6Al-7Nb alloys for dentures

We aimed to evaluate the effect of a denture cleanser and NaOCl 5.25% solution on the modulus of elasticity, the ultimate stress, and the weight changes of Co-Cr and Ti-6Al-7Nb alloys. To evaluate the modulus of elasticity and ultimate stress, 24 Co-Cr and 24 Ti-6Al-7Nb castings were fabricated, immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Thirty-six castings were produced to evaluate weight changes, 18 Co-Cr and 18 Ti-6Al-7Nb, and immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Changes in the modulus of elasticity, ultimate stress, and weight were calculated before and after immersion in the cleanser or NaOCl 5.25% solution for 45 cycles of 10 min each. Two-way analysis of variance ANOVA and Tukey's test at α = 0.05 were used to analyze the data. The modulus of elasticity and the ultimate stress of Co-Cr decreased after immersion in the solutions. The same properties of Ti-6Al-7Nb decreased in NaOCl 5.25% and increased in the other solutions. Weight loss was observed in Co-Cr alloy in both Corega Extradent and NaOCl 5.25%. A weight increase was observed in Co-Cr in water. An increase was observed in Ti-6Al-7Nb in Corega Extradent, NaOCl 5.25%, and water. The highest decrease (P = 0.05) in the modulus of elasticity and ultimate stress in Co-Cr were observed in NaOCl 5.25%, whereas no statistically significant differences (P > 0.05) were observed in Ti-6Al-7Nb in any of the solutions. A statistically significant weight loss (P < 0.05) was observed when Co-Cr was immersed in NaOCl 5.25%, and a statistically significant weight increase (P > 0.05) was observed when Ti-6Al-7Nb was immersed in Corega Extradent. The Co-Cr alloy bending properties after immersion fulfilled ADA Specification No. 14 for satisfactory clinical performance.