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| ORIGINAL RESEARCH |
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| Year : 2023 | Volume
: 15
| Issue : 1 | Page : 78-83 |
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Antifungal effect of acrylic resin denture base containing different types of nanomaterials: A comparative study
Mohamed A A Ismaeil1, Mohamed I Ebrahim2
1 Department of Prosthodontics, College of Dentistry, Taif University, Taif, Saudi Arabia
2 Faculty of Dental Medicine, Al-Azhar University, Cairo, Egypt; Department of Restorative Dental Science, College of Dentistry, Taif University, Taif, Saudi Arabia
| Date of Submission | 12-Mar-2022 |
| Date of Decision | 21-Oct-2022 |
| Date of Acceptance | 06-Nov-2022 |
| Date of Web Publication | 28-Feb-2023 |
Correspondence Address:
Dr. Mohamed A A Ismaeil
Department of Prosthodontics, Faculty of Dentistry, Taif University, Taif
Saudi Arabia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jioh.jioh_62_22
Aim: Denture stomatitis is a frequent condition that has an influence on denture users’ oral mucosa, and it is related to the presence of Candida albicans. Silver and titanium nanoparticles are antimicrobial agents with a broad spectrum of activity. This research sought to represent and compare the antifungal properties of acrylic resins modified with two concentrations of silver nanoparticles (AgNPs) and titanium-oxide nanoparticles (TiO2 NPs) against a clinical isolate of C. albicans. Materials and Methods: One-hundred discs of acrylic resin specimens were classified into five groups based on nanoparticles’ concentration: group A: unmodified acrylic resin; groups B1 and B2: modified by adding 0.5% and 1% AgNPs to the acrylic resin powder, respectively; groups C1 and C2: modified by adding 0.5% and 1% TiO2 NPs to the acrylic resin powder, respectively. The antimicrobial efficacy of different acrylic resin discs against C. albicans clinical isolates was assessed using disc agar diffusion and elution tests (surface-plate method). The analysis of variance test was employed to evaluate the data that differentiate among means of different groups at P ≤ 0.05 significance level. Results: The bioactivity and biomass of C. albicans biofilm reduced as the nanoparticle content rises; about 0.5%, 1% of AgNPs, and 1% TiO2 NPs exhibited higher antimicrobial and antibiofilm effects against C. albicans clinical isolates caused by inhibition zone and reduction of the colony counts. Conclusion: Acrylic resins modified by adding AgNPs or TiO2 NPs exhibited antimicrobial activity against C. albicans clinical isolates. Keywords: Acrylic Resin, Antimicrobial Agents, Candida albicans, Nanoparticles, Silver, Titanium Oxide
How to cite this article:
Ismaeil MA, Ebrahim MI. Antifungal effect of acrylic resin denture base containing different types of nanomaterials: A comparative study. J Int Oral Health 2023;15:78-83 |
How to cite this URL:
Ismaeil MA, Ebrahim MI. Antifungal effect of acrylic resin denture base containing different types of nanomaterials: A comparative study. J Int Oral Health [serial online] 2023 [cited 2023 Apr 1];15:78-83. Available from: https://www.jioh.org/text.asp?2023/15/1/78/370752 |
| Introduction | |  |
The most utilized acrylic resin is polymethyl methacrylate (PMMA) material in the fabrication of removable dentures completely and partially. Despite its beneficial qualities, PMMA denture base resin has several drawbacks that continue to be troublesome in prosthodontic clinical procedures, such as surface roughness and apparent porosity, which can function as a source of bacteria.[1],[2] Furthermore, poor denture hygiene causes surface scrapes, debris collection, and biofilm development, all of which contribute to denture stomatitis and inflammatory alterations in the adjacent mucosa.[1],[3]
Hover PMMA is oversensitive to colonization by different microbial species including Candida because of its topographic surface.[2]Candida species particularly Candida albicans have emerged as the most often identified pathogenic fungus in the clinical practice.[4] It is capable of forming pathogenic biofilms on the denture-fitting surface, leading at the end to denture stomatitis.[5]
The treatment of denture stomatitis is one of the difficulties faced during dental care. According to epidemiological research, around 70% of user’s removable denture anguish from denture stomatitis. Acrylic resin has adequate mechanical, physical, and esthetic properties; however, it may contribute to biofilm formation and microbes’ adhesion, especially C. albicans because of the rough surface of the denture, which is a prerequisite for denture stomatitis.[2],[6]
Many researchers have proposed various antifungal treatment techniques for denture stomatitis because it is considered as a fungal disease.[7]
Other studies mentioned by several investigations, covering the acrylic resin surface with 2-octyl cyanoacrylate, nanoacrylic films, silane-SiO2, or experimental coatings comprising zwitterion or hydrophilic monomers, prevent C. albicans adherence.[8],[9]
Because of their exceptional physical and chemical capabilities, nanosized materials have been utilized in many sophisticated applications in health sciences. Recently, there has been a lot of interest in integrating nanoparticles into PMMA to improve its qualities, such as TiO2, SiO2, ZnO, CeO2, Ag, CuO, and so on, to induce antimicrobial capabilities. PMMA is commonly reinforced and improved by the use of nanosilver and nanotitanium.[10],[11]
Silver nanoparticles (AgNPs) have high antimicrobial activity and have shown potent inhibition of Candida, equivalent to amphotericin B. Studies on the mechanisms and targets of AgNPs have indicated that the hydroxyl radicals and reactive oxygen species produced by AgNPs disrupt the cell membrane and mitochondria of a fungus, leading to apoptosis.[12],[13]
Titanium oxide (TiO2) has recently gained popularity because of its notable catalytic function, white color, low toxicity, high stability, sufficiency, and inexpensive cost. Titanium oxide nanoparticles (TiO2 NPs) have a strong antimicrobial activity through photocatalysis. The modification of denture base acrylic resin with TiO2 nanotubes could improve its antimicrobial properties. Adding TiO2 nanoparticles to heat-polymerized acrylic resin material of denture base could affect the amounts of C. albicans.[14],[15]
There is a noticeable difference in the concentrations used in the literature dealing with the antifungal effect of the nanometals mixed with denture base resin on C. albicans.[16] This means that more studies may be needed to select the most suitable concentrations of nanometals that can be used as antifungal materials. Most previous studies have shown the antimicrobial and antibiofilm activities of TiO2 NPs and silver nanoparticles incorporated into the composition of acrylic resins. Still, there is a shortage of reports that compare the effect of various TiO2 NPs and AgNPs concentrations.[17]
Till now, there are not enough studies conducted to compare the antifungal properties of acrylic resin modified by various kinds of nanoparticles.[18] This study was to assess antifungal effectiveness of acrylic resins modified by adding different concentrations of AgNPs and TiO2 NPs against C. albicans.
| Materials and Methods | | |
This comparative in vitro study has been done in research laboratory in the Faculty of Dentistry at Taif University from August 2018 to March 2021. Data have been collected by both authors.
Specimens’ preparation
Nanoparticles used in the present study
Particles of the AgNPs with average size of 40 nm spherical form with olic acid and of the TiO2 with average size of 50 nm anatase form were purchased from Mknano Company (Mknano Company, M K Impex Corp, 6382 Lisgar Drive Mississauga, ON L5N 6 × 1, Canada). Polyvinyl pyrrolidone 2.0% was used as a stabilizer.
Specimen fabrication and specimens grouping
According to nanoparticle concentration, 100 discs of acrylic resin were prepared and separated into five groups (20 discs per group) [Table 1].
While group A (control group) is unmodified acrylic resin (Major base, Trevalon/Universal Clear–DENTSPLY, Konstanz, Germany), groups B1 and B2 were modified by incorporating silver (AgNPs) by 0.5% and 1% by weight into the acrylic resin powder, and groups C1 and C2 were modified by incorporating TiO2 NPs by 0.5% and 1% by weight into the acrylic resin powder.
Nanoparticles were merged with PMMA powder in an amalgamator at the research laboratory at the College of Dentistry, Taif University, to obtain a good distribution in the acrylic resin powder. Stainless steel mould (diameter 10 cm with 2mm thickness) was used to prepare specimens of acrylic resin directly through packing of acrylic resin into this mould [Figure 1]. This mold consists of three parts: the upper and lower cover part, the inner part containing holes for packing the material, and four screws for securing the material to the mold. | Figure 1: Mold used in the preparation of the samples used in the present study
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The PMMA polymer and monomer were combined as stated by manufacturer’s recommendations. The mixture was manually kneaded till it appeared to dough stage. The acrylic resin was packed and treated in a heat-curing machine for 2 h at 74°C, followed by 1 h at 100°C (KaVo Elektrotechnisches Werk GmbH, Leutkirch, Germany). Before deflasking, the metal mold was allowed to cool at ambient temperature.
In order to finish and polish the specimens, a tungsten carbide bur (HM 79GX-040 HP; Meisinger) with a thin crosscut at 18.000 rpm was employed, followed by a fine-grain cylindrical rubber top bur for the acrylic resin (HM251FX-040-HP; Meisinger).[7]
A mechanical polisher (Metaserve 250 grinder-polisher, Buehler) was used to polish a polishing cloth disc (TexMet C10 in, 42-3210, Buehler GmbH) at 100 rpm for 5 min in wet circumstances. Five test groups were assigned at random to the sound heat-polymerized acrylic resin specimens (no rough surface, incorrect packing, or shattered sections). Following ultrasonic cleaning, the specimens were incubated at 37°C for 1 week in distilled water, which was changed daily to limit the buildup of residual monomers.[19]
Microbiological analyses
Microbial strain
The microbial identification was performed using biochemical assays.[20],[21]
Preparation of yeast culture solution
The suspension solution of the C. albicans clinical isolates was prepared in yeast–mold culture medium (Hi-Media Laboratories Pvt Ltd, Mumbai, India) at 37°C for 24–48 h. The overnight culture was diluted to the desired concentration after being adjusted to a McFarland factor of 0.5 (106 CFU/mL; CFU, colony-forming unit).[20],[21]
Assessment of biofilm formation of C. albicans clinical isolates
As a result of the presence of visible film, the biofilm production capacity of yeast isolate was examined using tube adherence test, a qualitative assay for the identification of biofilm-producing microorganisms.[22] The isolate’s overnight culture was injected in a polystyrene test tube with yeast–mold agar (Hi-Media Laboratories Pvt Ltd, Mumbai, India) and incubated at 37°C for 24 h. Decanted tubes were rinsed twice with phosphate-buffered saline, PBS (pH = 7.2), and curt. 0.1% crystal violet was used to dye dried tubes. Deionized water was used to remove the excess discoloration. The tubes were then dried inverted to allow biofilm growth. The biofilm development was regarded positive when a visible film coated the tube’s wall and bottom. The creation of rings at the liquid contact did not indicate the establishment of a biofilm. Experiments were carried out in duplicate and three times.
Attachment of C. albicans to acrylic samples
Before microbial assay, all samples of acrylic were sterilized by submerging them in 70% alcohol for 10 min[23]; after that, 1 min of washing in ultrapure water and subsequently subjected to ultraviolet ray sterilization for 15 min. Each acrylic sample was put in a test tube with 5 mL of C. albicans solution and incubated at 37°C for 4 h. Following that, each sample was removed and washed three times in PBS. The growth of C. albicans adhering to the surface of acrylic resin specimens was examined.[24]
Evaluation of the antifungal activity of acrylic resin
The antimicrobial activity of acrylic resin discs was evaluated via diffusion and elution methods.
Disc agar diffusion test
The antimicrobial disc activity through the diffusion of AgNPs and TiO2 NPs was tested by disc agar diffusion (DAD). All the resin specimens were embedded with slight pressure in Muller Hinton agar medium (Hi-Media Laboratories Pvt Ltd, Mumbai, India) that injected with a 100 μL solution of Candida (≈106 CFU/mL) by a sterile swab. The difference in Candida growth inhibition after 48 h of incubation produced zone that visually measured around control and treated resin discs. The greater the diameter of the inhibitory zone, the greater antimicrobial activities of nanoparticles compared with the control group.
Eluted components’ antibacterial properties
The antimicrobial activity of AgNPs and TiO2 NPs released from acrylic discs was evaluated using this technique. In tubes containing 2 mL of yeast malt broth, acrylic resin discs were put. After 72 h, the discs were transferred to sterile tubes, and 50 L of the Candida culture (final concentration of 105 CFUs/mL) was included in each tube containing 2 mL of yeast malt broth. For 24 h, the tubes were shaken at 300 rpm at 37°C. The suspension was serially diluted in microtiter plates before being spread out in yeast malt agar. The surface-plate technique was used to count the Candida colonies (CFUs/mL).
Statistical analysis
For statistical analysis, SPSS software was utilized (IBM SPSS Statistics, V 25, IBM, Armonk, NY, USA). The data were described using the mean and standard deviation. For comparing the mean numbers of C. albicans and the width of inhibition zone diameter in nanoparticles groups, one-way analysis of variance was utilized. Pairwise comparison between each group was made using Tukey’s post hoc tests. At P < 0.05, differences were judged statistically significant.
| Results | | |
The results of the DAD test showed that an application of the AgNPs (0.5% and 1%) and TiO2 NPs (1%) blended in PMMA acrylic resin discs significantly inhibits the growth of C. albicans by disc diffusion in comparison to unmodified PMMA discs control group (P < 0.001). There were no inhibition zones around the control group and 0.5% TiO2 NPs acrylic samples, as shown in [Table 2]. | Table 2: Antifungal activity of different resin groups studied by DAD test
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The component elution test revealed that the antifungal properties of the modified acrylic resin against C. albicans-eluted components meaningfully reduced colony counts of C. albicans-suspended media compared with the unmodified control group (P < 0.001) [Table 3]. The TiO2 NPs discs (1%) and AgNPs discs (0.5%, 1%) demonstrated the strongest antifungal performance compared with the unmodified control group. | Table 3: Comparison between the different studied groups according to elution methods
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| Discussion | | |
The current research aims to assess the influence of various kinds of nanoparticles on the denture’s Candida. An incorporation of AgNPs into the denture resin is a promising technique against C. albicans.[18] Many investigators have noticed the antibiofilm activity of several types of nanometals including AgNPs against C. albicans.[25],[26] Takamiya et al.[27] assessed the antifungal effect of silver colloidal nanoparticles against C. albicans- and Candida glabrata-adhered cells and biofilms. They found that AgNPs were more effective. In contrary, some authors found the incorporation of AgNPs into a denture base acrylic resin and did not observe any influence on C. albicans adherence and biofilm formation.[28]
Other research indicated that the antimicrobial efficacy of TiO2 NPs is in the order of Escherichia coli > Pseudomonas aeruginosa > Staphylococcus aureus > Enterococcus faecium > Candida albicans, with the order being dictated mostly by the complexity and density of the cell membrane/wall.[29]
So that in the current research, the authors aimed to evaluate the antifungal activity of modified denture base resin with two different nanometals, namely AgNPs and TiO2 NPs. The groups with the AgNPs 0.5%, AgNPs 1%, and TiO2 NPs 1% blended discs showed a potent antifungal and antibiofilm activity. The unmodified and 0.5% TiO2-modified groups were not as effective as previous groups in antimicrobial and antibiofilm potential. This inhibitory effect of nanoparticles is attributed to the ability of NPs to adhere and penetrate the cell membrane. These will lead to the disturbance of the cell function by releasing the active ions. Some investigators found that TiO2 NPs mixed with PMMA lead to a significant decrease in surface porosity of the acrylic resin, which in turn decrease the growth of Candida hyphae. AgNps have a small size that facilitate their entry into the cell membrane of the Candida leading to rabid antibacterial effect.[30]
The present study results showed that the number of colonies of viable yeast in the acrylic resin plates in the treated groups was significantly less than untreated control group, demonstrating the fungicidal activity of acrylic resins containing TiO2 NPs and AgNPs against C. albicans.
In the current study, adding nanoparticles to acrylic specimens could reduce Candida growth and population, so could inhibit biofilm formation.
Regarding the nanoparticles, it may be concluded that the higher the concentration, the higher the antimicrobial and antibiofilm activity. Hence, a concentration of 1% turned out to be more fungicidal than 0.5% when TiO2 NPs and AgNPs are employed. This result is consistent with the findings of other investigators.[17]
Although our study found that adding Ag and TiO2 NPs to acrylic resin dentures inhibited the growth of Candida albicans, additional research is required to determine optimal concentration of nanoparticles.
The limitation of this study includes the limited range of concentration used in the samples, and the influence of color and mechanical properties on the samples should be included in further studies.
| Conclusions | | |
In conclusion, adding AgNPs and TiO2 NPs to the acrylic resin can control C. albicans proliferation, an important oral cavity pathogen. The antimicrobial test results confirmed a considerable antifungal activity of acrylic resin denture base material involving these types of nanoparticles, namely TiO2 NPs and AgNPs against C. albicans. The results revealed that there is no obvious difference between the two materials in the ability to resist C. albicans proliferation. Hence, using these types of modified acrylic resin can be a promising approach in dentistry.
Future scope/clinical significance
AgNPs and TiO2 NPs addition to PMMA could be used in the prevention of denture stomatitis among completely edentulous patients.
Acknowledgment
The authors would like to acknowledge to Dr. Sabry Hasan, Professor of Bacteriology and Immunology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt, and Professor Mostafa Ibrahim Fayad at Taibah University, Faculty of Dental Medicine.
Financial support and sponsorship
This study was self-funded.
Conflicts of interest
There are no conflicts of interest.
Author contributions
All the authors have made major contributions to the development and writing of this article. The final article has been reviewed and approved by all writers.
Ethical policy and institutional review board statement
The study was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2000, and the study and the study protocol were approved by the institutional ethical committee of Al-Azher University, AssuitEgypt (AUAREC20200004-01).
Patient declaration of consent
Not applicable.
Data availability statement
The data that support the findings of this study are available on request from the corresponding author Mohamed Ashour Ahmed; e-mail: [email protected]
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[Figure 1]
[Table 1], [Table 2], [Table 3]
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