Strategies for Preventing and Treating Oral Mucosal Infections Associated with Removable Dentures: A Scoping Review.

Oral infections occur due to contact between biofilm rich in Candida albicans formed on the inner surface of complete dentures and the mucosa. This study investigated historical advances in the prevention and treatment of oral mucosal infection and identified gaps in the literature. Bibliographic research was conducted, looking at PubMed, Embase, Web of Science, and Scopus, where 935 articles were found. After removing duplicates and excluding articles by reading the title and abstract, 131 articles were selected for full reading and 104 articles were included. Another 38 articles were added from the gray literature. This review followed the PRISMA-ScR guidelines. The historical period described ranges from 1969 to 2023, in which, during the 21st century, in vitro and in vivo studies became more common and, from 2010 to 2023, the number of randomized controlled trials increased. Among the various approaches tested are the incorporation of antimicrobial products into prosthetic materials, the improvement of oral and denture hygiene protocols, the development of synthetic and natural products for the chemical control of microorganisms, and intervention with local or systemic antimicrobial agents. Studies report good results with brushing combined with sodium hypochlorite, and new disinfectant solutions and products incorporated into prosthetic materials are promising.

Antimicrobial activity of essential oils against biofilms formed in dental acrylic resin: a systematic review of in vitro studies.

This study aimed to answer the question formulated according to the PICO strategy: 'Which essential oils show antimicrobial activity against biofilms formed on dental acrylic resin?' composed by population (dental acrylic resin), intervention (application of essential oils), comparison (denture cleansers, antifungal drugs, chlorhexidine, and oral mouthwashes), and outcome (antibiofilm activity). In vitro experimental studies evaluating the activity of EOs on biofilm formed on acrylic resin were included. PRISMA guidelines were followed, and the search was performed in the PubMed, Science Direct, Embase, and Lilacs databases and in the gray literature using Google Scholar and ProQuest in December 2023. A manual search of the reference lists of the included primary studies was performed. Of the 1467 articles identified, 37 were selected for full-text reading and 12 were included. Twelve EOs were evaluated, of which 11 showed activity against Candida spp., 3 against Staphylococcus aureus, and 1 against Pseudomonas aeruginosa. The EOs of Cymbopogon citratus, Cinnamomum zeylanicum, and Cymbopogon nardus showed higher action than chlorhexidine, C. nardus higher than Listerine, C. citratus higher than nystatin, and Melaleuca alternifolia higher than fluconazole and nystatin. However, chlorhexidine was more effective than Lippia sidoides and Salvia officinalis, sodium hypochlorite was more effective than L. sidoides, nystatin was more effective than Zingiber officinale, Amphotericin B more effective than Eucalyptus globulus and M. alternifolia. In conclusion, the EOs of C. zeylanicum, C. citratus, C. nardus, and M. alternifolia showed antimicrobial activity to reduce biofilm on dental acrylic resin.

Effect of immersion in disinfectants on the color stability of denture base resins and artificial teeth obtained by 3D printing.

PURPOSE: To evaluate the effect of immersion in disinfecting solutions on the color stability of denture base resins and artificial teeth obtained by 3D printing. MATERIALS AND METHODS: Forty discs (15 × 3 mm) were obtained for each group: Lucitone 550 and Cosmos Denture 3D (denture base resins), Duralay and Cosmos TEMP 3D (artificial teeth resins). The discs were immersed in disinfectant solutions: Corega Tabs, 2% chlorhexidine digluconate, 0.25% sodium hypochlorite, and distilled water. Color measurements were obtained with a spectrophotometer before immersion in disinfectants and after the simulated periods of 6 and 12 months. Data (ΔE00 ) were submitted to mixed three-way ANOVA and Bonferroni post-test. RESULTS: For denture base resins, Cosmos Denture 3D showed greater color change regardless of the solution and immersion time. The immersion time of 6 months influenced the color change of the denture base resins regardless of the disinfectant solution. For the artificial teeth resins, the immersion time of 12 months showed a significant color change when compared to 6 months. Cosmos TEMP 3D showed greater color change for all solutions, except for 0.25% sodium hypochlorite. Duralay resin showed greater color change in 2% chlorhexidine, regardless of immersion time. CONCLUSIONS: For denture base resins, the immersion time significantly changed the color regardless of the solution. For artificial teeth resins, Cosmos TEMP 3D showed greater color changes in all solutions when compared to Duralay, except for 0.25% sodium hypochlorite. Chlorhexidine digluconate significantly changed the color of Duralay.

Microbiological, physicomechanical, and surface evaluation of an experimental self-curing acrylic resin containing halloysite nanotubes doped with chlorhexidine.

OBJECTIVE: The objective was to synthesize halloysite nanotubes loaded with chlorhexidine (HNT/CHX) and evaluate the antimicrobial activity, microhardness, color change, and surface characteristics of an experimental self-curing acrylic resin containing varying concentrations of the synthesized nanomaterial. METHODS: The characterization of HNT/CHX was carried out by calculating incorporation efficiency, morphological and compositional, chemical and thermal evaluations. SAR disks were made containing 0 %, 3 %, 5 %, and 10 % of HNT/CHX. Specimens (n = 3) were immersed in distilled water and spectral measurements were carried out using UV/Vis spectroscopy to evaluate the release of CHX for up to 50 days. The antimicrobial activity of the composite against Candida albicans and Streptococcus mutans was evaluated by disk-diffusion test. Microhardness, color analyses (ΔE), and surface roughness (Ra) (n = 9) were performed before and after 30 days of immersion. Data were analyzed using ANOVA/Bonferroni. {Results.} The incorporation efficiency of CHX into HNT was of 8.15 %. All test groups showed controlled and cumulative CHX release up to 30 or 50 days. Significant antimicrobial activity was verified against both microorganisms (p < 0.001). After the 30-day immersion period, the 10 % HNT/CHX group showed a significant increase in hardness (p < 0.05) and a progressive color change (p < 0.001). At T0, the 5 % and 10 % groups exhibited Ra values similar to the control group (p > 0.05), while at T30, all groups showed similar roughness values (p > 0.05). {Significance.} The modification of a SAR with HNT/CHX provides antimicrobial effect and controlled release of CHX, however, the immediate surface roughness in the 3 % group was compromised when compared to the control group.

Functional Acrylic Resins Prepared via Photo-Induced Telomerization Using Tetrabromomethane as Telogen.

Novel method of obtaining functional acrylic resins (FARs) containing carboxyl- and benzophenone groups (in-chain functionalization) and terminal Br atoms was verified. Acrylic oligomers were prepared by a solution-free, UV-initiated telomerization process of basic monomer (n-butyl acrylate) and functional monomers (acrylic acid and 4-acrylooxybenzophenone) in the presence of radical photoinitiator and different amount of tetrabromomethane (CBr4) as telogen. The effect of telogen content on UV-telomerization kinetics as well as physicochemical and thermal (Tg) properties of FARs was investigated. A telogen content higher than 5 wt. parts does not affect the UV-telomerization rate (photo-DSC), the molecular weights of telomers (GPC), or their glass transition temperature (DSC), but it significantly increases the conversion of monomers (up to 88%) and lowers the viscosity of FARs (approx. 6 Pa·s). NMR studies confirmed the inclusion of CBr4 in the structure of functional acrylic telomers.

Application of Laser Treatment in Adhesive Bonding of Liners to Polymethyl Methacrylate Denture Resins: A Systematic Review and Meta-Analysis.

Objective: This systematic review and meta-analysis aimed to assess the influence of laser treatment on adhesive bonding of liners to polymethyl methacrylate (PMMA) denture base resins. Methods: The focused question was: "Does the application of laser treatment (Intervention) influence the adhesive bonding strength (Outcome) of liners to PMMA denture base resins (Population) as compared with untreated or unconditioned surfaces (Control)?" In vitro and clinical reports as well as reports on influence of laser treatments on bonding strength of liners to PMMA denture resins in comparison with untreated surfaces were included. Reports without any control group[s], without any application of laser[s] for PMMA denture bases that did not utilize PMMA denture bases, and not evaluate bond strength of PMMA denture base resins were excluded. An electronic search was conducted on PubMed, Scopus, and Web of Science. Meta-analyses were performed for calculating the standard mean difference (SMD) with a 95% confidence interval (95% CI). Results: Nine of the 12 included studies found that laser irradiation treatment produced significant surface texture alterations of the PMMA denture base and improved the adhesion between the PMMA denture base and soft lining. According to the meta-analysis, tensile bond strength showed an SMD of -2.49% (95% CI: -3.89 to -1.08; p = 0.0005), suggesting a statistically significant difference between the control and test groups (i.e., favoring laser-treated samples than untreated samples). Regarding shear bond strength scores, the outcomes showed an SMD of -2.24% (95% CI: -3.79 to -0.69; p = 0.005), suggesting a statistically significant difference between the control and test groups (i.e., favoring laser-treated samples than untreated samples). Conclusions: Despite the high heterogeneity among the included studies, it can be concluded that laser treatment might improve the bonding strengths of liners to PMMA denture base resins as compared with untreated surfaces. To validate the aforementioned conclusions, further verification is required through the implementation of well-designed randomized controlled trials with large sample sizes.

Temporary fixed prosthesis materials and beverage colorants: an in vitro study.

The esthetic outcome of temporary prostheses, especially those in the anterior area, is of primary importance. The purpose of this in vitro study was therefore to evaluate the color stability of 3 temporary restorative materials: self-curing (SC) acrylic resin (Tempron); heat-curing acrylic resin (SR Ivocron); and polymethyl methacrylate resin blocks (Telio CAD) machined using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The heat-curing material was polymerized with either a pressure-curing technique (PT) or a flasking technique (FT). As a result, there were 4 experimental groups: SC, PT, FT, and CAD/CAM. Sixteen specimens were prepared for each group. After polymerization or milling, all specimens were polished using a diamond polishing paste, and 1 specimen from each group was exposed to Fourier-transform infrared (FTIR) and ultraviolet visible (UV-Vis) spectroscopy before immersion. The specimens were exposed to pigmented beverage agents (coffee, cola, turmeric solution, or tea), and the color change was monitored for 4 weeks using FTIR and UV-Vis spectroscopy as well as by macroscopic observation of the specimens (n = 4 per group per immersion period). The PT specimens showed the most significant color change, followed by the SC specimens. A less significant color variation was noted in the FT specimens, and insignificant change was reported in the CAD/CAM group. The solution that had the most significant staining effect was turmeric, and the CAD/CAM resin showed the greatest color stability of the tested materials. Color stability depends on the material used, the polymerization technique, the polishing steps, the pigmentation agent, and the duration of exposure to the agent.

The Antibacterial and Antifungal Activity of Chlorhexidine Diacetate Incorporated into Acrylic Resins Used in Provisional Restorations.

Objective: The surface of provisional restorations applied before conventional or implant- supported fixed restorations may cause bacterial or fungal biofilm formation. The aim of this study was to evaluate the antimicrobial activity of acrylic resins used in provisional restorations modified with chlorhexidine diacetate. Methods: 120 cylindrical, auto-polymerized resin samples modified with chlorhexidine diacetate were prepared at concentrations of 0 (control), 1, 3, 5 wt %. The antimicrobial activity was examined against Streptococcus mutans, Enterococcus faecalis, and Candida albicans using Crystal Violet quantification, MTT assay, and Scanning Electron Microscopy. Data were analyzed by ANOVA and paired sample t-tests (α=0.05). Results: The addition of chlorhexidine diacetate influenced the growth rate and metabolic activity of microorganisms. The antimicrobial effect against C. albicans and S. mutans statistically increased with the percentage of chlorhexidine diacetate. E. faecalis bacteria were less affected by chlorhexidine diacetate compared to other pathogens. Conclusion: It has been shown that the effectiveness of CHDA in inhibiting the proliferation of microorganisms correlated positively with increasing concentration levels. More research is needed to confirm the impact of different chlorhexidine concentrations on the mechanical properties, clinical efficacy, and antimicrobial properties of CDHA.

Investigating the biocompatibility, flexural strength, and surface roughness of denture base resin containing copper oxide nanoparticles: An in vitro study.

Aim: This study aimed to evaluate the biocompatibility, flexural strength, and surface roughness of polymethyl methacrylate (PMMA) containing Copper Oxide Nanoparticles (CuO NPs) at different concentrations. Methods: 25 heat-polymerized PMMA wax patterns fabricated in 5 groups containing 0.5, 5, 50, and 500 µg/ml CuO NPs and nanoparticle (NP)-free PMMA discs were prepared. 5 growth mediums (DMEM with 10% FBS and 1% penicillin-streptomycin) without disks were also incubated similarly to serve as the control groups. The cytotoxicity of the discs was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on cultured Human Gingival Fibroblasts. The number of 1.3 × 104 cells were seeded in each well of 96-well plates (5 wells for the extract of each specimen). Days 1, 3, 5, and 7 were the intervals that the culture media were in direct contact with the PMMA discs for either 24 or 72 h. After that, a total of 40 specimens with 65 × 10 × 2.5 mm dimensions were prepared in five groups (n = 8). The specimens were subjected to a rugosimeter for the evaluation of surface roughness. The flexural strength test was performed using a universal testing machine. Microscopic evaluation was performed for the dispersion of the NPs. Non-parametric Kruskal-Wallis test and parametric one-way ANOVA test were used for data analysis. Results: The samples containing 500 µg/ml NPs showed the lowest percentage of cell viability at all incubation periods, while the highest cell viability was observed in NP-free PMMA 24 h after the seventh day of incubation. NPs at 50 and 500 µg/ml concentrations showed strongly significant differences in cytotoxicity compared to the 0 concentration and the control group (p < 0.001). Although all the samples demonstrated an increasing pattern of cell viability on the third, fifth, and seventh days, the percentage of cell viability was significantly lower after 72 h than after 24 h in all incubation periods (p < 0.001). NPs significantly increased flexural strength (p = 0.005) but did not affect the surface roughness of the PMMA discs (p = 0.396). Significance: The CuO NPs were cytotoxic only when applied in high concentrations, but presented a descending trend over time. No cytotoxic effect was observed in the experimental groups after seven days of incubation. Furthermore, CuO NPs increased flexural strength, but the surface roughness of the PMMA discs was not affected.

Air-polishing technology is an effective alternative chairside method for cleaning dentures.

AIMS: To investigate the efficiency and abrasiveness of air-polishing on different types of denture base acrylic resins and whether air-polishing can be an effective technique to clean dentures chairside. MATERIALS AND METHODS: A total of 60 specimens were prepared (n = 20/group); heat-polymerized polymethyl methacrylate (PMMA) (G1), subtractive manufacturing (SM) (G2) and additive manufacturing (AM) denture base resins (G3). Equal number of specimens in each group were stained with permanent marker or nail polish and pumice mixture to mimic calcified biofilm. All specimens were treated using EMS Airflow® Prophylaxis Master with two different powders; erythritol or sodium bicarbonate powder, following manufacturer instructions. Efficacy of the powders and surface roughness of the specimens were measured. Scanning electron microscopy imaging was captured for qualitative observation. RESULTS: The highest efficacy for stain removal was found in erythritol powder on G1 (98.06% ± 1.304%). The lowest was found in the erythritol powder on G3 (91.83% ± 3.611%). The highest efficacy for biofilm removal was found in sodium bicarbonate powder on G3 (71.49% ± 8.607%), and the lowest was found in erythritol powder on G2 (11.64% ± 4.68%). Only AM resins had statistically significant increases in surface roughness with the use of erythritol powder (p < 0.001). The use of sodium bicarbonate powder significantly increases surface roughness of heat-polymerized (p < 0.025) and AM resins (p < 0.724). CONCLUSIONS: Air-polishing technology has shown to be effective and suitable for cleaning dentures. The sodium bicarbonate powder showed superior efficacy in cleaning dentures compared to the erythritol powder. Both powders show varyingly increase roughness depending on denture resin.

Experimental Study on Mechanical Properties of Different Resins Used in Oral Environments.

Background and Objectives: Acrylic resins remain the materials of choice for removable prosthesis due to their indisputable qualities. The continuous evolution in the field of dental materials offers practitioners today a multitude of therapeutic options. With the development of digital technologies, including both subtractive and additive methods, workflow has been considerably reduced and the precision of prosthetic devices has increased. The superiority of prostheses made by digital methods compared to conventional prostheses is much debated in the literature. Our study's objective was to compare the mechanical and surface properties of three types of resins used in conventional, subtractive, and additive technologies and to determine the optimal material and the most appropriate technology to obtain removable dentures with the highest mechanical longevity over time. Materials and Methods: For the mechanical tests, 90 samples were fabricated using the conventional method (heat curing), CAD/CAM milling, and 3D printing technology. The samples were analyzed for hardness, roughness, and tensile tests, and the data were statistically compared using Stata 16.1 software (StataCorp, College Station, TX, USA). A finite element method was used to show the behavior of the experimental samples in terms of the crack shape and its direction of propagation. For this assessment the materials had to be designed inside simulation software that has similar mechanical properties to those used for obtaining specimens for tensile tests. Results: The results of this study suggested that CAD/CAM milled samples showed superior surface characteristics and mechanical properties, comparable with conventional heat-cured resin samples. The propagation direction predicted by the finite element analysis (FEA) software was similar to that observed in a real-life specimen subjected to a tensile test. Conclusions: Removable dentures made from heat-cured resins remain a clinically acceptable option due to their surface quality, mechanical properties, and affordability. Three-dimensional printing technology can be successfully used as a provisional or emergency therapeutic solution. CAD/CAM milled resins exhibit the best mechanical properties with great surface finishes compared to the other two processing methods.

Using Peek as a Framework Material for Maxillofacial Silicone Prosthesis: An In Vitro Study.

There are often bonding problems between acrylic resins and silicone. PEEK (polyetheretherketone), which is a high-performance polymer, has great potential for the implant, and fixed or removable prosthodontics. The aim of this study was to evaluate the effect of different surface treatments on PEEK to be bonded to maxillofacial silicone elastomers. A total of 48 specimens were fabricated from either PEEK or PMMA (Polymethylmethacrylate) (n = 8). PMMA specimens acted as a positive control group. PEEK specimens were divided into five study groups as surface treatments as control PEEK, silica-coating, plasma etching, grinding, or nano-second fiber laser. Surface topographies were evaluated by scanning electron microscopy (SEM). A platinum-primer was used on top of all specimens including control groups prior to silicone polymerization. The peel bond strength of the specimens to a platinum-type silicone elastomer was tested at a cross-head speed of 5 mm/min. The data were statistically analyzed (α = 0.05). The control PEEK group showed the highest bond strength (p < 0.05) among the groups. No statistical difference was found between control PEEK, grinding, or plasma etching groups (p > 0.05). The lowest bond strength was seen in the laser group, which was not statistically different from silica-coating (p > 0.05), and statistically different from control PEEK, grinding, or plasma groups (p < 0.05). Positive control PMMA specimens had statistically lower bond strength than either control PEEK or plasma etching groups (p < 0.05). All specimens exhibited adhesive failure after a peel test. The study results indicate that PEEK could serve as a potential alternative substructure for implant-retained silicone prostheses.

Antifungal Effect of Ginger Essential Oil Spray on Candida albicans Adhering to Self-Cure Acrylic Plates.

Objectives: The present study aimed to evaluate the efficacy of ginger essential oil spray for elimination of Candida albicans (C. albicans) adhering to self-cure acrylic plates. Materials and Methods: In this experimental study, 120 self-cure acrylic discs were contaminated with C. albicans and randomly divided into four main groups: exposure to ginger essential oil, nystatin (positive control), distilled water (negative control), and no exposure. The minimum inhibitory concentration (MIC) of ginger oil and nystatin was determined by the microdilution test. The stability of C. albicans was determined by culturing the samples of treated acrylic plates and comparing the mean number of remaining colonies. Data were analyzed using the Kruskal-Wallis test followed by Dunn test with Bonferroni correction. P<0.05 was considered significant Results: The MIC of ginger essential oil and nystatin was found to be 1560µg/mL and 4µg/mL, respectively. The differences between the mean count of C. albicans colonies before (10175±10730.25) and after the exposure to ginger essential oil (542.86±464.81) and nystatin (257.14±247.67) was statistically significant (P<0.001). The mean number of C. albicans colonies after spraying with nystatin was not significantly different compared with ginger essential oil (P=0.204). The efficacy of nystatin and ginger essential oil at each time was significantly more than distilled water (P<0.001). At 10 and 15min, there was no significant difference between nystatin and ginger essential oil groups (P=0.05). Conclusion: Ginger essential oil spray was found to be a simple and effective method for elimination of C. albicans adhering to acrylic discs.

Cytotoxicity of cleaning agents for ocular prostheses.

BACKGROUND: Polymethylmethacrylate (PMMA) is the most used material for the manufacturing of eye prostheses. OBJECTIVES: To investigate the cytotoxicity of different cleaning agents for ocular prostheses on human conjunctival cells. MATERIAL AND METHODS: Six groups of specimens were created (saline, soap, 4% chlorhexidine, hydrogen peroxide, 1% triclosan, and citronella oil). Three specimens were made for each disinfectant at each disinfection period (1, 7, 15, 30, 60, and 90 days), totaling 108 specimens. Thus, the specimens were disinfected, with different disinfectants, for different periods of time. After each disinfection process, the specimens were washed with sterile distilled water. A human conjunctival cell line was grown on the acrylic resin specimens and then cytotoxicity tests (MTT and Neutral Red (NR)) were performed. A negative control (untreated cell cultures) and positive control (Tween 20) were created. Two-way analysis of variance (ANOVA) and Bonferroni test were performed (p < 0.05). RESULTS: For the MTT and NR tests, when there was a significant difference between the disinfectant and negative control, the disinfectant generated a significant reduction in cell proliferation most of the time. CONCLUSIONS: All reductions in cell proliferation caused by the disinfectants were clinically acceptable. All disinfectants tested in this study were found to be non-cytotoxic to human conjunctival cells.

Understanding the Mechanical, Surface, and Color Behavior of Oral Bioactive Prosthetic Polymers under Biodegradation Processes.

Changes in the properties of resin-based polymers exposed to the oral environment can emerge when chlorhexidine (CHX) is incorporated to develop bioactive systems for treating denture stomatitis. Three reline resins loaded with CHX were prepared: 2.5 wt% in Kooliner (K), 5 wt% in Ufi Gel Hard (UFI), and Probase Cold (PC). A total of 60 specimens were submitted to physical aging (1000 cycles of thermal fluctuations, 5-55 °C) or chemical aging (28 days of pH fluctuations in artificial saliva, 6 h at pH = 3, 18 h at pH = 7). Knoop microhardness (30 s, 98 mN), 3-point flexural strength (5 mm/min), and surface energy were tested. Color changes (ΔE) were determined using the CIELab system. Data were submitted to non-parametric tests (α = 0.05). After aging, bioactive K and UFI specimens were not different from the controls (resins without CHX) in mechanical and surface properties. Thermally aged CHX-loaded PC specimens showed decreased microhardness and flexural strength but not under adequate levels for function. The color change was observed in all CHX-loaded specimens that underwent chemical aging. The long-term use of CHX bioactive systems based on reline resins generally does not impair removable dentures' proper mechanical and aesthetic functions.

Nanocurcumin Release from Self-Cured Acrylic Resins; Effects on Antimicrobial Action and Flexural Strength.

The placement of orthodontic appliances into the oral area can lead to infection, inflammatory and gingival collapse. Using an antimicrobial and anti-inflammatory material in the matrix of orthodontic appliance may help to reduce these issues. This study aimed to assess the release pattern, the antimicrobial action and the flexural strength of self-cured acrylic resins after adding different weight percentages of curcumin nanoparticles (nanocurcumin). In this in-vitro study, 60 acrylic resin samples were divided into five groups (n = 12) based on the weight percentage of curcumin nanoparticles added to the acrylic powder (0 for control, 0.5, 1, 2.5, and 5%). Then, the dissolution apparatus was used for the release assessment of nanocurcumin form the resins. For antimicrobial action assessment, the disk diffusion method was used and a three-point bending test was performed with a speed of 5 mm/min to determine the flexural strength. Data were analyzed using one-way analysis of variance (ANOVA) and Post-Hoc Tukey tests (with p < 0.05 as significant level). The microscopic images showed the homogeny distribution of nanocuricumin in self-cured acrylic resins in varied concentrations. The release pattern showed a two-step release pattern for all concentrations of nanocurcumin. The one-way ANOVA outcomes indicated that adding curcumin nanoparticles to self-cured resin increased the diameter of the inhibition zones for the groups against Streptococcus mutans (S. mutans) significantly (p < 0.0001). Additionally, as the weight percentage of curcumin nanoparticles increased, the flexural strength decreased (p < 0.0001). However, all strength values were higher than the standard value (50 MPa). No significant difference was detected between the control group and the group with 0.5 percent (p = 0.57). Considering the proper release pattern and the potent antimicrobial activity of curcumin nanoparticles, then the preparing self-cured resins containing curcumin nanoparticles can be beneficial for antimicrobial aims without damaging the flexural strength to use in orthodontic removable applications.

Antimicrobial Photodynamic Therapy as a Technique for Decontamination of Acrylic Resin Devices Provided by Different Dental Laboratories.

Introduction: Dentures, occlusal splints, surgical guides and orthodontic appliances are examples of acrylic resin devices made in dental laboratories, which must be disinfected and even sterilized before insertion into the oral cavity. This study evaluated the antimicrobial effect of photodynamic therapy (PDT) applied to acrylic resin specimens received from different laboratories. Methods: Three hundred standardized specimens were ordered from six randomly selected laboratories registered in the Council of Dentistry of Ceará (n=50). The PDT consisted in the association of 22 µM erythrosine, as a photosensitizer (P), and a 520-nm LED at 38 J/cm2 (L). The specimens of each laboratory were randomly distributed into five groups: positive control, sterilized with ethylene oxide; negative control, untreated (P-L-); erythrosine control, only stained (P+L-); LED control, only irradiated (P-L+); PDT (P+L+). Then, the specimens were individually sonicated in saline solution; the suspension was diluted, plated on culture mediums (blood agar, sabouraud dextrose agar and a non-selective chromogenic agar), and incubated for 48 hours at 37°C. Colony-forming-unit (CFU) counts were done and statistical tests of Kruskal-Wallis/Dunn were carried out. Results: The specimens from all laboratories were contaminated with bacteria and yeasts. Staphylococcus aureus, Staphylococcus saprophyticus, Escherichia coli, Enterococcus spp., Klebsiella and Pseudomonas spp. were identified. The PDT significantly reduced CFU counts (P<0.0001), compared to P-L-. Conclusion: PDT was able to effectively decontaminate the acrylic resin specimens provided from dental laboratories.

The Influence of Saliva pH on the Fracture Resistance of Two Types of Implant-Supported Bis-Acrylic Resin Provisional Crowns-An In Vitro Study.

Temporary restorations play a fundamental role in oral rehabilitation. A properly adapted implant-supported provisional restoration implies better esthetics, contouring and architectural modeling of the upper peri-implant tissue. This study aimed to evaluate the influence of oral pH on the fracture resistance of implant-supported provisional restorations made with two brands of bis-acrylic resin (LuxaCrown® and Protemp™ 4) and to compare the fracture resistance of these two materials. Twenty crowns (ten manufactured using each brand) served as a control, and another forty crowns (twenty of each brand) were aged using artificial saliva with pHs of 4 or 7, for 7 days at 37 °C, in an attempt to simulate the behavior of these materials inside the oral cavity. Subsequently, all crowns were subjected to the application of a force at a constant speed, in a universal testing machine, until fracture was achieved. The LuxaCrown® brand showed greater resistance to fracture than the Protemp™ 4 brand. Salivary pH did not influence the fracture resistance of provisional LuxaCrown® crowns but did influence the fracture resistance of provisional Protemp™ 4 crowns.

Efficacy of Denture Cleansers on Microbial Adherence and Surface Topography of Conventional and CAD/CAM-Processed Denture Base Resins.

This study assessed the efficacy of five denture cleansers on the microbial adherence and surface topography of conventional and CAD/CAM denture base resins. Acrylic resin discs were fabricated using conventional, milling, and 3D printing methods (N = 180). The discs were contaminated with dual species of Candida albicans and Streptococcus mutans biofilm for 72 h and then disinfected with either of the denture cleansers (Fittydent cleansing tablets, 2% Chlorhexidine gluconate, 0.2% Chlorhexidine gluconate, 0.5% sodium hypochlorite, and 1% sodium hypochlorite (n = 10). Distilled water served as the control group. The colony-forming units of the microorganisms were calculated, followed by post-treatment surface roughness. Data were statistically analyzed using one-way ANOVA, paired t-test, and post hoc Tukey HSD test (α = 0.05). Among the denture cleansers, 2% Chlorhexidine gluconate, 0.5% sodium hypochlorite, and 1% sodium hypochlorite had the best cleansing effect on the resin discs and demonstrated zero growth of colonies for both the species. Comparing the material groups, the 3D-processed discs showed higher colony-forming units followed by the conventional and CAD/CAM milled group. The highest surface roughness was demonstrated by the 3D-printed discs (0.690 ± 0.08 µm), followed by the conventional (0.493 ± 0.11 µm) and the milled groups (0.301 ± 0.08 µm). The tested chemical denture cleansers affected the Candida albicans and Streptococcus mutans adhesion compared to control discs immersed in distilled water. The clinician may recommend to their patient to use 2% chlorhexidine gluconate for the disinfection of CAD/CAM PMMA denture base materials.

Antibiofilm effect of cleaning agents for ocular prostheses.

Introduction: This study aimed to evaluate the antibiofilm effect of different agents (neutral soap, 4% chlorhexidine, Efferdent effervescent tablets, 1% triclosan, and citronella essential oil) used for ocular prosthesis cleaning. Material and Methods: Biofilms of S. aureus and S. epidermidis were formed on 60 ocular prosthesis acrylic resin specimens. The specimens were cleaned with the studied agents with different techniques. Microorganism counting was performed. Data were submitted to ANOVA and HSD Tukey-Kramer (p<.01). Results: When compared to the control group, all cleaning protocols promoted a reduction in growth of microorganisms. The 4% chlorhexidine, effervescent tablets, and 1% triclosan cleaning agents eliminated biofilm in all groups. Conclusion: Therefore, immersion in 4% chlorhexidine, effervescent tablets, and 1% triclosan could be the best protocols indicated for ocular prosthesis cleaning due to their ability to eliminate biofilm.