Effects of two novel denture cleansers on multispecies microbial biofilms, stain removal and the denture surface: an in vitro study

The effect of soaking heat-polymerized acrylic resin denture base in avocado seed extract ( Persea americana Mill.) on the inhibition of denture-plaque microorganisms biofilm growth

Background

Heat polymerized acrylic (HPA) resins are known to have high porosity that contributes to increased surface roughness and microcrack formation in stress areas. This facilitates the attachment and growth of polymicrobial biofilms contributing to increased antimicrobial resistance. This research aims to study avocado seeds effect on denture-plaque microorganism mono-species and polymicrobial biofilm on HPA resin.

Methods

This study uses 144 samples (n=144), namely HPA resin discs covered with mono-species and polymicrobial biofilms. The discs are soaked for 8 hours in the 5%, 10%, 15%, 20% avocado seed extract, positive control (alkaline peroxide), and negative control (aquadest). Each disc is shaken with a vortex mixer for 1 minute, and 100 μL is added into 96-well microplates with three times repetition and incubated for 24 hours. A microtiter plate biofilm formation assay is then conducted. The inhibition values are determined from the percentage inhibition value formula which requires absorption values from a microplate reader (595 nm). The research data are analyzed using a univariant test, and a one-way ANOVA test, accompanied by Welch ANOVA on non-homogenous data.

Results

In this research, it is found that the MBIC 50 of avocado seed extract against the mono-species of C. albicans (5%), C. glabrata (5%), A. odontolyticus (15%), S. gordonii (15%), S. aureus (10%), while against polymicrobial was 20%. There is a significant effect of soaking HPA resin in avocado seed extract on the inhibition of mono-species and polymicrobial biofilms with a value of p<0.001 (p<0.05).

Conclusion

The MBIC 50 of avocado seed extract in polymicrobial biofilm group is higher than that in the mono-species biofilm groups. Hence, 20% avocado seed extract is concluded as the effective concentration to inhibit denture-plaque microorganism biofilm.

The study of the base resin impact on planktonic growth of microorganisms of oral origin

OBJECTIVE

Aim: To study the main differences in the intensity of growth of microbial strains of oral origin when they are cultivated in the presence of base resins that are widely used in the clinic of prosthetic dentistry.

PATIENTS AND METHODS

Materials and Methods: 3 types of base resin samples were used to evaluate the impact on the growth of microorganisms. Strains of opportunistic pathogens representing the facultative anaerobic transient microflora of the oral cavity were used for the research. Microbial cultures were isolated from the oral mucosa of the patients with removable dentures. The optical density of the culture was determined using a multi-mode photometer. Control growth of the cultures was evaluated under similar cultivation conditions in test tubes with a nutrient medium without resin samples.

RESULTS

Results: All resins reduced the intensity of polyantibiotic-resistant S. aureus MRSA growth compared to control samples. The impact on S. epedermidis growth was different. Thus, Vertex and Вreflex reduced the growth intensity insignificantly, and Villacryl increased it to the level of 1.104 ±0.026 CU in comparison with glass constituting 1.178 ±0.033 CU. All studied resins inhibited the growth of polyantibiotic-resistant S. aureus MRSA. Villacryl resin had the least impact on the growth of S. epedermidis. Villacryl resin inhibited C. albicans growth only by 13.70%, and the other two resins inhibited it by 25% on average.

CONCLUSION

Conclusions: The conducted microbiological studies showed the diverse influence of base materials on such important indicators as the optical density of cultures grown in the presence of base resins and the growth inhibition index of cultures.

Adsorption, Adhesion, and Wettability of Commercially Available Cleansers at Dental Polymer (PMMA) Surfaces

This study aims to evaluate the adsorptive, adhesive, and wetting energetic properties of five commercially available cleansers in contact with model dental polymer (PMMA). It was assumed that the selected parameters allow for determining the optimal concentration and place of key component accumulation for antibacterial activity in the bulk liquid phase and prevention of oral plaque formation at the prosthetic material surface. The adsorptive (Gibbs' excesses ΓLV, critical micellar concentration) and thermal (entropy and enthalpy) surface characteristics originated from surface tension γLV(T) and γLV(C) dependences. The surface wetting properties were quantified upon the contact angle hysteresis formalism on the advancing ΘA, receding ΘR contact angles, and γLV as the input data, which yield a set of wettability parameters: 2D adsorptive film pressure, surface free energy with its dispersive and polar components, work of adhesion, and adhesional tension, considered as interfacial interaction indicators. In particular, molecular partitioning Kp and ΓLV are indicators of the efficiency of particular active substance accumulation in the volume phase, while γSV, a = ΓSL/ΓLV, and WA point to the degree of its accumulation at the immersed polymer surface. Finally, the liquid penetration coefficient PC and the Marangoni temperature gradient-driven liquid flow speed were estimated.

Biological, Antifungal, and Physical Efficacy of a Denture Cleanser Formulated with Cnidium officinale Extracts

BACKGROUND/OBJECTIVES

We aimed to assess the antifungal efficacy and impact of a denture cleanser containing Cnidium officinale extract on the surface characteristics of denture base materials, as well as its physical and biological properties.

METHODS

The experimental denture cleansers were formulated with C. officinale at concentrations of 100 and 150 μg/mL, combined with 1% cocamidopropyl betaine as a natural surfactant. Antifungal efficacy was evaluated using zone-of-inhibition assays against Candida albicans, revealing inhibition zones of 20 ± 1.8 mm for the 100 μg/mL concentration and 23.6 ± 1.6 mm for the 150 μg/mL concentration. Surface property assessments-including hardness, roughness, color stability, and solubility measurements-demonstrated no significant differences compared to the control group. Biological evaluations included the quantification of polyphenol and flavonoid content.

RESULTS

The C. officinale-based cleanser showed significant antifungal activity without affecting the hardness, roughness, color stability, or solubility of denture base materials. Biological tests revealed no cytotoxicity and minimal mucosal irritation. Polyphenol and flavonoid contents were quantitatively measured, revealing higher concentrations in the experimental groups, which were correlated with significant antifungal activity. These compounds are known for their roles in disrupting microbial processes and enhancing antimicrobial effects. These findings suggest that the C. officinale-based denture cleanser effectively inhibits C. albicans while preserving the physical properties of denture base materials.

CONCLUSIONS

This study highlights the potential of C. officinale in denture cleanser formulations, promoting denture hygiene and oral health. Future research should prioritize long-term clinical evaluations and formulation optimization.

Anti-biofilm effectiveness of protocols for cleaning complete dentures in hospitalized patients: a randomized controlled trial

BACKGROUND

Denture biofilm acts as a potential reservoir for respiratory pathogens, considerably increasing the risk of lung infections, specifically aspiration pneumonia, mainly 48h after hospital admission. The establishment of a straightforward, affordable, and applicable hygiene protocol in a hospital environment for the effective control of denture biofilm can be particularly useful to prevent respiratory infections or reduce the course of established lung disease.

OBJECTIVES

To evaluate the anti-biofilm effectiveness of denture cleaning protocols in hospitalized patients.

METHODOLOGY

The maxillary complete dentures (MCDs) of 340 hospitalized participants were randomly cleaned once using one of the following 17 protocols (n=20): brushing with distilled water, toothpaste, or neutral liquid soap (controls); immersion in chemical solutions (1% sodium hypochlorite, alkaline peroxide, 0.12% or 2% chlorhexidine digluconate), or microwave irradiation (650 W for 3 min) combined or not with brushing. Before and after the application of the protocols, the biofilm of the intaglio surface of the MCDs was evaluated using two methods: denture biofilm coverage area (%) and microbiological quantitative cultures on blood agar and Sabouraud Dextrose Agar (CFU/mL). Data were subjected to the Wilcoxon and Kruskal-Wallis tests (α=0.05).

RESULTS

All 17 protocols significantly reduced the percentage area of denture biofilm and microbial and fungal load (P<0.05). The highest percentage reductions in the area of denture biofilm were observed for 1% hypochlorite solution with or without brushing and for 2% chlorhexidine solution and microwave irradiation only in association with brushing (P<0.05). The greatest reductions in microbial and fungal load were found for the groups that used solutions of 2% chlorhexidine and 1% hypochlorite and microwave irradiation, regardless of the association with brushing (P<0.05).

CONCLUSIONS

A single immersion for 10 min in 1% sodium hypochlorite, even in the absence of brushing, proved to be a straightforward, rapid, low-cost, and effective protocol for cleaning the dentures of hospitalized patients.