Microbial contamination of removable dental prosthesis at different interval of usage: An in vitro study

Novel antimicrobial applications of copper oxide nanoparticles after combination with tissue conditioner used in complete prostheses

BACKGROUND

Tissue conditioners are used for treating and improving the tissues supporting complete dentures. On the other hand, recent advances in nanotechnology have revolutionized various fields of science, including dentistry. The present study aimed to investigate novel antimicrobial applications of copper oxide nanoparticle-based tissue conditioner used in complete prostheses.

METHODS

The present experimental study included 126 tissue conditioner samples with different concentrations of copper oxide nanoparticles (20%, 10%, 5%, 2.5%, 1.25%, 0.625%, and 0% w/w). The samples were incubated with Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans in 24-well plates for 24 h. Then, samples from the wells were re-incubated for 24 h, and the microorganisms were counted.

RESULTS

The culture media containing E. faecalis and P. aeruginosa showed significantly different growth between different nanoparticle concentrations following 24 h (P < 0.001), showing a reduction in bacterial growth with increased nanoparticle concentration. Both bacteria did not show any growth at the 20% concentration. However, C. albicans showed significant differences in growth between different nanoparticle concentrations following 48 h (P < 0.001), showing a reduction in growth with increased nanoparticle concentration. Also, the least growth was observed at the 20% concentration.

CONCLUSIONS

In conclusion, the CuO nanoparticles were prepared using a green synthesis methon in the suitable sizes. Moreover, the tissue conditioners containing CuO nanoparticles showed acceptable antimicrobial properties against E. faecalis, P. aeruginosa, and C. albicans.

Prevalence of respiratory pathogens colonizing on removable dental prostheses in healthy older adults: A systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to investigate the prevalence of opportunistic respiratory pathogens colonizing removable dental prostheses in older adults without respiratory diseases.

METHODS

This review was registered with PROSPERO and conducted in accordance with the principles formed by the working group of the Joanna Briggs Institute (JBI) to evaluate systematic reviews of prevalence data. Literature searches were conducted across five electronic databases. Quality assessments were determined according to a revised JBI critical appraisal checklist across nine criteria. Comparison between fixed- and random-effects meta-analyses were performed for sensitivity analysis. Prediction intervals were also presented when three or more studies were included in the meta-analysis.

RESULTS

Across the databases, 1091 articles were identified, and 591 articles remained after the removal of duplicates. Twenty "potentially effective" studies were identified. Ultimately eight studies informed this review and meta-analyses were performed for 13 known respiratory pathogens. The meta-analyses identified the top three common respiratory pathogens residing on the removable prostheses were, in descending order: Staphylococcus aureus: 31.81% (95% CI: 13.34%-48.24%); Staphylococcus epidermidis: 14.07% (95% CI: 7.88%-21.48%); Klebsiella pneumoniae: 10.50% (95% CI: 2.55%-22.30%). The heterogeneity scores for nine respiratory pathogen analyses were classified as "unimportant inconsistency", I2 = 0% (p > 0.1). For sensitivity analysis, there was no difference between the random- and fixed-effects models.

CONCLUSION

The existing evidence demonstrated a high burden of certain opportunistic respiratory pathogens, which may be considered a major potential cause of respiratory infections in older adults wearing removable prostheses.

Qualitative assessment of the removable denture microbiome

Introduction

Assessment of the denture plaque can provide a valuable report regarding the oral health of geriatric patients and the oral hygiene habits in this population group. Focusing on the current research gap on this topic in Romania, our research aims to highlight the microbial plaque on the different surfaces and types of removable poly(methyl methacrylate) (PMMA) prostheses to qualitatively evaluate the microbial species, and to assess the combined effect of mechanical and chemical cleaning of dentures on the prosthetic microbiome.

Methods

The prosthetic plaque from four denture wearers was identified with a UV activated fluorescent revealer and digitally photographed. Swab samples according to a certain hygiene protocol were cultured on three different growth media such as blood agar (BA), bromothymol blue lactose agar (AABTL) and Sabouraud dextrose agar (SDA).

Results

Denture plaque was variably distributed on the surface of the prostheses. Regardless of the denture type (conventional complete denture, tooth or implant supported overdenture, removable partial denture) the microbial plaque was identified at the retentive areas, especially at interdental spaces. The main plaque deposition areas were the vestibular incline of the labial flange of the maxillary denture and the lingual incline of the posterior lingual flange of the mandibular denture. The prosthetic microbiome consisted of pathogenic Gram-positive aerobes (Streptococcus spp. and coagulase-negative Staphylococcus spp.), Gram-positive anaerobes (Actinomyces spp. and Klebsiella spp.) as well as subspecies of fungi of the genus Candida.

Conclusions

Despite its poor variety, the denture microbiome in the investigated cases hosts colonies with high pathogenic potential. Some areas of the prostheses are more likely to accumulate dental plaque. Dentists should insist through more regular checks of the patients and their caregivers on ensuring the biocontrol of the dentures, especially in frail geriatric patients exposed to greater risks related to general health.

Evaluation of microbial contamination in removable dental prosthesis at different time of usage

Aim

The current study evaluates and compares the percentage distribution of different microorganisms according to their strains and occurrence among the three studied groups.

Method and Methodology

Sample of 30 removable dental prosthesis wearing patients was selected: wearing either complete dentures or partial dentures and without any significant medical history or on prescription medication for the past 3-6 months. Samples were obtained in three subcategories based on the duration of prostheses worn by the patient. A sterile swab made up of cotton moistened with phosphate buffer saline (PBS) was scrubbed on the dental prosthesis at the fitting surfaces and the denture-bearing area of the oral cavity. Within two hours, the collected swab sample was infused in the sterile tube containing 1 ml of 0.84% PBS solution maintained at pH 7-7.2 and sent for microbiological analysis. The samples were then inoculated into different medias. Microbial growth was checked after incubating the culture plates for 48 h at 37°C. Microorganisms were recognized and counted by calibrated colony counter. Gram's stain was used to stain the colony smear and biochemical tests such as coagulase, catalase, oxidase, sugar fermentation with acid and gas production (triple sugar iron), methyl red test, test for indole production, hydrogen sulphide (H2S) production, citrate utilization, urease test, germ tube tests were performed.

Statistical Analysis

Descriptive statistics included calculation of means and standard deviation using multivariate analysis. All values were considered statistically significant for a value of P < 0.05.

Results

Streptococcus species, Coagulase-negative staphylococcus, Staphylococcus aureus, Candida albicans and Klebsiella pneumoniae showed the maximum positive culture among the secluded microorganisms in all three groups.

Conclusion

A progressive increase in the microbial contamination was directly proportional to the duration of removable prosthesis usage.

Evaluation of red-complex bacteria loads in complete denture patients: a pilot study

OBJECTIVE

This pilot study aimed to evaluate red-complex bacteria (RCB) loads in edentulous patients, before and after dentures' insertion.

MATERIALS AND METHODS

Thirty patients were included in the study. Deoxyribonucleic acid (DNA) isolated from bacterial samples were obtained from the dorsum of the tongue before and 3 months after complete dentures (CDs) insertion in order to identify the presence of RCB (Tannerella forsythia, Porphyromonas gingivalis, and Treponema denticola) and quantify their loads, using real-time polymerase chain reaction (RT-PCR). Bacterial loads were represented as "Lg (genome equivalents/sample)" and the data classified according to the "ParodontoScreen" test.

RESULTS

Significant changes in bacterial loads were observed before and 3 months after the CDs insertion for: P. gingivalis (0.40 ± 0.90 vs 1.29 ± 1.64, p = 0.0007), T. forsythia (0.36 ±0.94 vs 0.87 ± 1.45, p = 0.005), and T. denticola (0.11 ± 0.41 vs 0.33 ± 0.75, p = 0.03). Before the CDs insertion, all patients had a normal bacterial prevalence range (100%) for all analyzed bacteria. Three months after the insertion, 2 (6.7%) of them had a moderate bacterial prevalence range for P. gingivalis, while 28 (93.3%) had a normal bacterial prevalence range.

CONCLUSION

The use of CDs has a significant impact on increasing RCB loads in edentulous patients.

Fracture strength of Er,Yag laser treated PMMA denture-based polymer (DBP) colonized with C. albicans, S. aureus, S.mutans, and E.coli

AIM

To assess and equate the efficacy of different disinfection protocols autoclave, chlorhexidine (CHX), PDT utilizing Rose Bengal (RB), chitosan, and Er, Yag laser and their effect on fracture strength of PMMA denture-based polymer (DBP) colonized with C. Albicans, S. aureus, S.mutans, and E.coli.

MATERIAL AND METHODS

A total of 50 (n = 10) PMMA DBP were manufactured and adulterated with the American Type Culture Collection (ATCC) of diverse microbial colonies inhabited by C. Albicans, S. aureus, S.mutans, and E.coli. The specimens were subjected to different denture disinfection approaches by randomly distributing in into five groups i.e., Er, Yag laser, RB, autoclave, CHX, and Chitosan, respectively for appraising antimicrobial effectiveness. PMMA fracture load was also assessed and statistical analysis was performed for CFU/mL (log10) of exposed C. Albicans, S. aureus, S.mutans, and E.coli by one-way ANOVA and Tukey's multiple comparison test at a significance level of p < 0.05.

RESULTS

Intergroup comparison disclosed that denture disinfection with Er, Yag laser, autoclave, Chitosan, and CHX (control) validated comparable antimicrobial efficacy to denture against all inspected CFU/mL (log10) (p>0.05). The intragroup comparison revealed that DBP sanitization with Er, Yag laser, autoclave, Chitosan, RB, and CHX substantiated equivalent effective antimicrobial efficacy in plummeting CFU/mL (log10) of S. mutans and E. coli (p>0.05) but in consideration to S.aureus and C.albicans, all groups resulted in declining their count except 5µm RB activated by PDT(p < 0.05). No significant difference was perceived in fracture load of PMMA denture base among Er, Yag laser, RB, chitosan, and CHX (control) (p > 0.05) except autoclave decontamination procedure that indicated the least fracture strength of DBP when disinfected (p < 0.05).

CONCLUSION

Er, Yag laser, and Chitosan activated by PDT have the potential to be used as an alternative to chlorhexidine for disinfecting Polymethyl methacrylate denture base as they demonstrated the highest antimicrobial efficacy against E. coli, C. Albicans, S aureus, and S. mutans with optimal fracture load.

Disinfection efficacy and fracture strength of PMMA denture-based polymer with chlorhexidine, PDT utilizing Rose Bengal and hematoporphyrin, and Er, Cr: YSGG laser

OBJECTIVE

The study aimed to assess and compare disinfection efficacy and fracture strength of PMMA based DBPs using chlorhexidine (CHX), PDT utilizing Rose Bengal (RB) and hematoporphyrin HPD, and Er,Cr:YSGG laser (ECL) induced antimicrobial action against in-vitro biofilms colonized with C.albicans, S.aureus, S. mutans, and E. coli.

MATERIAL AND METHODS

American Type Culture Collection (ATCC) of C.albicans, S.aureus, S. mutans and E. coli were cultured. Forty-eight PMMA-based denture base plates (DBPs) were prepared by heat-cure acrylic resin and contaminated by in-vitro biofilm under-stimulated in-vitro conditions. DBPs were treated with group1; ECL group 2; RB 5µm, group 3; HPD 500 mg/L and group 4; 0.12% CHX (controls) respectively, for the disinfection of biofilms. All photosensitizers (PS) were activated by LED at a different wavelength. Each contaminated DBP was sprayed on all its surfaces with the aforementioned photosensitizers and CHX. One-way analysis of variance (ANOVA) was used to test the efficacy of disinfection and fracture load testing. Tukey multiple comparison tests were performed to compare means of CFU/mL (log10) for exposed E. coli, C. albicans, S aureus, and S. mutans.

RESULTS

Specimens in group 1 disinfected with erbium laser, group 3 disinfected with HPD, and group 4 sterilized with chemical disinfection were effective in decreasing bacterial load CFU/mL (log10) against C.albicans, S. aureus, S.mutans, and E. Coli (p>0.05). Intergroup comparison demonstrated ECL, CHX and HPD demonstrated a comparable reduction against C.albicans and S.aureus (p>0.05). Similarly, S.mutans and E.coli were sensitive against all experimental groups (p>0.05). no significant difference in fractural load analysis among the different investigated groups was noted (p>0.05).

CONCLUSION

ECL and HPD photosensitizer revealed a significant reduction in CFU/ml of exposed viable colonies of C.albicans, S.aureus, S. mutans, and E. coli comparable to 0.12% CHX mediated disinfection of PMMA-based DBPs. Irrespective of the type of disinfection no influence of disinfection was noted on the fracture load of PMMA DBPs.

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.

Nanostructured silver vanadate decorated with silver particles and their applicability in dental materials: A scope review

OBJECTIVES

The present study aims to evaluate which studies evaluated the effectiveness of incorporating silver vanadate into dental materials and to analyze the influence of this incorporation on antimicrobial activity and material properties.

DATA

This review was led by the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist and the JBI Briggs Reviewers Manual to answer the following question:Does the nanostructured silver vanadate decorate with silver particles present anti-microbial activity when incorporated into dental materials without altering its mechanical properties?

SOURCE

An electronic search without restriction on the dates or languages was performed in PubMed/MEDLINE, Web of Science, Lilacs, Scopus, and Embase up until 2020. The search was specified and limited to the use of the words "nanostructured silver vanadate" in double quotation marks.

STUDY SELECTION

The initial search resulted in 55 articles. After an initial assessment and careful reading, 15 studies published between 2014 and 2020 were included in this review.

CONCLUSIONS

With the present scope review, it was possible to observe the good interaction between AgVO3 and dental materials and have a clarity that it is possible to use them in different types of materials in order to reduce the probability of infections resulting from the biofilm that is installed in them.

Disinfection of acrylic denture resin polymer with Rose Bengal, Methylene blue and Porphyrin derivative in photodynamic therapy

AIM

The study aimed to assess the effect of in-vitro chlorhexidine and antimicrobial photodynamic therapy (aPDT) disinfection protocols against acrylic resin specimens colonized with S. mutans, S. aureus, E. coli, and C. albicans.

MATERIAL AND METHODS

Reference strains of S. mutans, S. aureus, E. coli, and C. albicans were tested. Sixteen blocks of acrylic specimens were prepared by heat-cure acrylic resin and contaminated by in-vitro biofilm growth. Specimens in group 1, group 2 and group 3 were treated with Rose Bengal (RB), methylene blue (MB) 500 mg/L and porphyrin derivative (PD) 5 ml respectively, for the sensitization of biofilms. All photosensitizers (PS) were activated by LED at different wavelength. CHX was prepared in sterile distilled water and applied for 60 s. Each contaminated specimen was sprayed on all its surfaces with the aforementioned photosensitizers and control CHX. One-way analysis of variance (ANOVA) model was used to test the effect of the treatments and Tukey multiple comparison tests to compare means OF CFU/mL (log10) for exposed E. coli, C. albicans, S aureus, and S. mutans RESULTS: Specimens treated with 0.12% CHX (control) demonstrated a significant reduction in CFU/mL (log10) for exposed E. coli; 2.04±0.07 CFU/mL, C. albicans; 2.09±0.85 CFU/mL, S aureus; 3.04±0.11 CFU/mL, and S. mutans; 2.54±0.91 CFU/mL. The intragroup comparison revealed E.coli did not exhibit a decrease in reduction CFU/mL (log10) when acrylic resin irradiated with RB 5 µm. Whereas, CFU/mL (log10) values of S.aureus; 3.62±0.68 and S.mutans; 3.41±0.13 plummeted (p<0.05). Intergroup comparison showed E.coli values to display comparable reduction when disinfected with MB 500 mg/L and 0.12% CHX; 3.16±0.34 and 2.04±0.07 CFU/mL (log10) (p<0.05).

CONCLUSION

Photosensitizers (RB, MB, PD) are selective in reducing bacterial count on acrylic resin blocks. CHX was found to be effective against all bacteria E.coli, C.albicans, S.aureus, and S.mutans at a concentration of 0.12%.

Composition's effect of Origanum Syriacum essential oils in the antimicrobial activities for the treatment of denture stomatitis

This research has several purposes: First to assess the bacterial and fungal minimum inhibitory concentration of Origanum Syriacum essential oil. Second to quantify its bactericidal and fungicidal minimal concentration against S. aureus, S. mutans, and C. albicans found in denture stomatitis. The third purpose is to look at the influence of three different soils (Annaya, Bhanin and Michrif) on the essential oils composition. Three essential oils were extracted by hydro-distillation from three different Origanum Syriacum plant origins. Bioassays were conducted using a broth microdilution methods. Gas Chromatography analysis was used to calculate the abundance of most components in each essential oil. Post hoc tests assessed antimicrobial effects between ecotypes while Pearson's test correlated the different components and their antimicrobial efficiency (α < 0.05). All tested essential oils were efficient against all microorganisms. Origanum Syriacum essential oils derived from Annaya and Bhanin soils showed a superior antimicrobial activity compared to the Michrif one. The most abundant component and most efficient among all essential oils constituents was carvacrol. It can be concluded that Origanum Syriacum essential oils have an antimicrobial activity, which depends on the ecotype, its origin and its composition. They might be used to start a clinical trial for the treatment of denture stomatitis.

Evaluation of the Efficacy of Different Cleaning Methods for Orthodontic Thermoplastic Retainers in terms of Bacterial Colonization

Objective

This study investigated the antimicrobial efficacy of three different cleaning methods on Streptococcus mutans (SM) and Lactobacillus (LB) bacteria colonization in vivo. The three different cleaning methods were applied by volunteers on clear vacuum formed retainers (VFRs).

Methods

In this prospective, cross-over study, a total of 21 volunteers were included. All VFRs used by the volunteers were cleaned using three different cleaning methods in a sequence. These methods were peroxide-based cleanser tablets (PBCTs) plus brushing, control (only brushing), and vinegar plus brushing, respectively. The obtained salivary, VFR material, and periodontal data were statistically compared by factorial design repeated measures analysis of variance.

Results

The SM and LB bacteria counts on VFRs after using both PBCTs and vinegar were statistically similar (p>0.05), but bacteria counts were statistically lower than the control method (p<0.01). There were no statistically significant differences between the SM and LB bacteria counts in saliva samples taken before and after the application of the cleaning methods (p>0.05). Similarly, there were no significant differences between periodontal data obtained from plaque and bleeding indices at all study times. The periodontal pocket depth gradually decreased in the successively performed cleaning applications (p<0.05).

Conclusion

The application of PBCTs and vinegar to VFRs at sequential time intervals resulted in similar bacteria counts. The higher LB counts and similarly higher SM counts on the VFR samples indicate that mechanical cleaning only (control method) is not adequate to obtain hygiene. Salivary flora was not correlated with bacteria counts of VFRs.

Silver Nanoparticles Addition in Poly(Methyl Methacrylate) Dental Matrix: Topographic and Antimycotic Studies

The widespread use of nanoparticles (NPs) in medical devices has opened a new scenario in the treatment and prevention of many diseases and infections owing to unique physico-chemical properties of NPs. In this way, silver nanoparticles (AgNPs) are known to have a strong antimicrobial activity, even at low concentrations, due to their ability to selectively destroy cellular membranes. In particular, in the field of dental medicine, the use of AgNPs in different kinds of dental prosthesis matrixes could be a fundamental tool in immunodepressed patients that suffer of different oral infections. Candida albicans (C. albicans), an opportunistic pathogenic yeast with high colonization ability, is one of the causative agents of oral cavity infection. In our work, we added monodispersed citrate-capping AgNPs with a size of 20 nm at two concentrations (3 wt% and 3.5 wt%) in poly(methyl methacrylate) (PMMA), the common resin used to develop dental prostheses. After AgNPs characterization, we evaluated the topographical modification of PMMA and PMMA with the addition of AgNPs by means of atomic force microscopy (AFM), showing the reduction of surface roughness. The C. albicans colonization on PMMA surfaces was assessed by the Miles and Misra technique as well as by scanning electron microscopy (SEM) at 24 h and 48 h with encouraging results on the reduction of yeast viability after AgNPs exposure.

Isolation and Identification of Nonoral Pathogenic Bacteria in the Oral Cavity of Patients with Removable Dentures

Aims and Objectives:

Dentures in the oral cavity may act as a reservoir of microorganisms, which may be related to systemic infections. The aim of this study was to investigate the nonoral pathogenic bacteria in the oral cavity of patients with removable dentures in Shiraz, Southern Iran.

Materials and Methods:

The bacterial flora of saliva samples from 50 men and 50 women with removable dentures and 100 age- and sex-matched controls with normal dentate were compared using culture, Gram staining, and API20E Kit methods. All data were analyzed using SPSS software.

Results:

Except for Enterobacter cloacae isolate (P = 0.03), there was no significant difference between both groups for the presence of Escherichia coli, Klebsiella pneumoniae, nonfermenting Gram-negative bacilli, Raoultella ornithinolytica, Raoultella planticola, Kluyvera spp., and Enterobacter aerogenes. No significant correlation was noticed between age and presence of bacteria in the oral cavity. The Gram-negative rod bacteria were more in males, but the difference was not significant. When a total of Gram-negative rods were considered, there was a significant difference between case and control groups (P = 0.004).

Conclusions:

Based on our findings that nonoral pathogenic bacteria are detected from the saliva of the denture wearers, general and oral health measures in patients with removable dentures should be adopted to decrease the risk of cross infection.

Elemental ion release and cytotoxicity of antimicrobial acrylic resins incorporated with nanomaterial

OBJECTIVES

This study evaluated the release of ions and the cytotoxicity of acrylic resins incorporated with silver vanadate decorated with silver nanoparticles (AgVO₃ ).

BACKGROUND

The inhibition of the accumulation of microorganisms on the resins is critical in preventing diseases. However, the hypothesis is that the release of ions from the incorporation of AgVO₃ may be important in biocompatibility.

MATERIALS AND METHODS

Specimens of autopolymerising (AP) and heat-polymerising resin (HP) with AgVO₃ were prepared and immersed in culture medium. The release of silver ions (Ag) and vanadium (V) was evaluated by mass spectrometry with inductively coupled plasma (ICP-MS) (n=9) and the cell viability of fibroblasts L929 by MTT (3-[4,5-dimethylthiazol- 2yl]-2,5-diphenyltetrazolium bromide) (n=12). The results were evaluated with analysis of variance (ANOVA), Tukey and Pearson correlation test (α=.05).

RESULTS

The groups containing AgVO₃ presented a difference in relation to the control (0%) regarding the release of Ag and V (P<.0001). All groups showed a reduction in L929 viability when compared with the cellular control (100%) (P<.0001). In comparison with the control resins for HP, a reduction in the metabolism of cells occurred starting at 2.5% and for AP at 5% (P<.0001). A positive correlation was found between the concentration of AgVO₃ and the ion release, and a negative between the ion release and the cell viability.

CONCLUSIONS

Significant numbers of Ag and V ions were released from resins with higher concentrations of AgVO₃ , presenting cytotoxicity for cells, suggesting that the use of low concentrations is indicated to avoid risks to patients.

Relative presence of Streptococcus mutans, Veillonella atypica, and Granulicatella adiacens in biofilm of complete dentures

Aims and Objective:

Oral biofilms in denture wearers are populated with a large number of bacteria, a few of which have been associated with medical conditions such as sepsis and infective endocarditis (IE). The present study was designed to investigate the relative presence of pathogenic bacteria in biofilms of denture wearers specifically those that are associated with IE.

Methods:

Biofilm samples from 88 denture wearers were collected and processed to extract total genomic DNA. Eight of these samples were subjected to 16S rRNA gene sequencing analysis to first identify the general bacterial occurrence pattern. This was followed by species-specific quantitative polymerase chain reaction (qPCR) on entire batch of 88 samples to quantify the relative copy numbers of IE-associated pathogens.

Results:

16S rRNA gene analysis of eight biofilm samples identified bacteria from Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, and Fusobacteria species. Interestingly, Streptococcus mutans, Veillonella atypica, and Granulicatella adiacens from Firmicutes, all known to be associated with early-onset sepsis and IE was present in five of eight biofilm samples. The other three samples carried bacteria from genus Proteobacteria with Neisseria flava and Neisseria mucosa, which are known to be commensals, as dominant species. Species-specific qPCR of S. mutans V. atypica, and G. adiacens on 88 biofilm DNA samples identified the presence of S. mutans in 83%, V. atypica in 79%, and G. adiacens in 76% of samples.

Conclusion:

The findings from the present study demonstrate co-occurrence of S. mutans, V. atypica, and G. adiacens in a majority of denture wearers, which is clinically significant as elderly patients with compromised immune system are more prone to develop IE. To the best of our knowledge, the co-occurrence of S. mutans, V. atypica, and G. adiacens is being reported for the first time in biofilms of denture wearers.