Evaluation of surface roughness, wettability and adhesion of multispecies biofilm on 3D-printed resins for the base and teeth of complete dentures.

OBJECTIVE: This study evaluated the surface roughness, wettability and adhesion of multispecies biofilms (Candida albicans, Staphylococcus aureus and Streptococcus mutans) on 3D-printed resins for complete denture bases and teeth compared to conventional resins (heat-polymerized acrylic resin; artificial pre-fabricated teeth). METHODOLOGY: Circular specimens (n=39; 6.0 mm Ø × 2.0 mm) of each group were subjected to roughness (n=30), wettability (n=30) and biofilm adhesion (n=9) tests. Three roughness measurements were taken by laser confocal microscopy and a mean value was calculated. Wettability was evaluated by the contact angle of sessile drop method, considering the mean of the three evaluations per specimen. In parallel, microorganism adhesion to resin surfaces was evaluated using a multispecies biofilm model. Microbial load was evaluated by determining the number of Colony Forming Units (CFU/mL) and by scanning electron microscopy (SEM). Data were subjected to the Wald test in a generalized linear model with multiple comparisons and Bonferroni adjustment, as well as two-way ANOVA (α=5%). RESULTS: The roughness of the conventional base resin (0.01±0.04) was lower than that of the conventional tooth (0.14±0.04) (p=0.023) and 3D-printed base (0.18±0.08) (p<0.001). For wettability, conventional resin (84.20±5.57) showed a higher contact angle than the 3D-printed resin (60.58±6.18) (p<0.001). Higher microbial loads of S. mutans (p=0.023) and S. aureus (p=0.010) were observed on the surface of the conventional resin (S. mutans: 5.48±1.55; S. aureus: 7.01±0.57) compared to the 3D-printed resin (S. mutans: 4.11±1.96; S. aureus: 6.42±0.78). The adhesion of C. albicans was not affected by surface characteristics. The conventional base resin showed less roughness than the conventional dental resin and the printed base resin. CONCLUSION: The 3D-printed resins for base and tooth showed less hydrophobicity and less adhesion of S. mutans and S. aureus than conventional resins.

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.

Unveiling the efficacy of latex gloves in preventing viral infections during needlestick injuries: An in vitro mixed-methods study.

BACKGROUND: Gloves are personal protective equipment designed to prevent contamination and reduce the spread of microorganisms. This study aimed to assess in vitro the physical integrity of latex gloves and the retention of biological contamination in healthcare simulation. METHOD: Three different batches of latex procedure gloves from five different brands and specific batches were evaluated before use for physical integrity by the standard protocols of the Society for Testing and Materials (ASTM) and of the American Food and Drug Administration (FDA). Moreover, the retention of biological contamination by latex procedure gloves in needlestick injury simulation with crystal violet and bacteriophages were applied in order to mimic human blood and virus presence. RESULTS: Brands D and C showed the best and worst results in the immediate inspections and after 2 min, respectively. For Brand C, damage occurred in one finger/region in a total of 12 gloves, while seven gloves were damaged/unable to be worn. Brand D presented only two gloves with tears and/or holes in one finger/region. Regarding the viral contamination, in a simulated needlestick injury, data showed no significant difference among the groups. CONCLUSION: All glove brands presented physical damage that might affect the spread of microorganisms. The gloves did not exert an additional protective effect during a needlestick injury simulation in accordance with the two techniques used in this study.

Relation between the risk factors for the severity of denture stomatitis and quality of life of complete edentulous individuals: a cross-sectional study.

OBJECTIVE: To assess the association between risk factors for developing denture stomatitis (DS) and oral health-related quality of life (OHRQoL) in complete denture wearers. METHODOLOGY: Participants of both sexes, wearing complete dentures, were classified using the modified Newton classification for the absence or the severity of DS and allocated to groups Normal or zero, IA, IB, II, and III. Lifestyle, oral and denture history, and medication use were assessed using specific questionnaires; clinical parameters such as anatomical characteristics of support were evaluated with the Kapur classification; salivary flow (SF) was calculated by the volume of unstimulated saliva per minute; and microbial load was determined by counting colony forming units (CFU) of target microorganisms present in the biofilm collected from dentures and palate. OHIP-EDENT assessed the OHRQoL. Kendall's tau_b and Spearman tests were applied with a significance level of 5%. RESULTS: 184 patients (143 female and 41 male) aged 65.5 ± 6.8 years were evaluated. Positive correlations were found for sex (women; p=0.013, r=0.16), individuals who started to consume alcoholic beverages as a young adult (18-27 years) (p=0.008, r=0.22), CFU of Candida spp. (p<0.001, r=0.27 denture; p<0.001, r=0.31 palate); Candida albicans (p=0.004, r=0.22 denture; p=0.003, r=0.25 palate), and Candida glabrata (p=0.004, r=0.22 denture; p=0.001, r=0.27 palate). Moreover, negative correlations with DS were found for CFU of Staphylococcus spp. (p=0.004, r=-0.20 palate) and enterobacteria (p=0.002, r=-0.24 palate), as well as a negative correlation between SF (p=0.009, r=-0.193) and DS. The CFU of Staphylococcus spp. and enterobacteria on the palate significantly correlated with OHRQoL. CONCLUSION: Being female, consuming alcoholic beverages as a young adult, CFU of Candida spp., Candida albicans, Candida glabrata, and salivary flow may be the most significant risk factors for DS. The microbial load of Staphylococcus spp. and enterobacteria seems to influence the quality of life for complete denture wearers.

Antimicrobial effect of phytosphingosine in acrylic resin.

This study evaluated color stability (CS), anti-adherence effect (AAE), and cell viability of microorganisms on acrylic resin (AR) surface, treated associated or not with sodium percarbonate (SP). AR specimens were prepared, and color analysis was performed before and after the treatments and the CS was calculated. For analysis of AAE, the samples were sterilized by radiation in a microwave oven. Then samples were randomly distributed: phosphate-buffered saline (PBS - control), 0.5% sodium hypochlorite (SH), phytosphingosine (PHS), and phytosphingosine + SP (PHS+Na2CO3). The specimens remained in contact with solutions for 30 minutes and were later contaminated by Candida albicans. Aliquots were seeded in Petri dishes with Sabouraud Dextrose agar and incubated at 37°C for 24 hours. After the incubation, the number of colonies was counted. The cell viability of adhered microorganisms on the AR was evaluated and 20 fields were observed under an epifluorescence microscope, and the percentage of adhered viable cells was calculated. Data were compared (One-way ANOVA, Tukey, p<.05). As for CS, PHS+ Na2CO3 (0.4±0.1) resulted in less change than PBS (0.9±0.2), similar to the other groups (SH [1.0±0.3)]; PHS [0.9±0.2)]). There was no difference for all tested solutions regarding the ability to avoid microorganism adherence (p>0.05), but PHS (11.2±4.1) resulted in a smaller area of adhered viable cells, statistically different from SH (18.2±7.6) and PBS (26.4±10.8). It was concluded that PHS resulted in lower adhered viable cells and when associated with Na2CO3, also shows a lower effect on the CS of AR.

Effect of Hygiene Protocols on the Mechanical and Physical Properties of Two 3D-Printed Denture Resins Characterized by Extrinsic Pigmentation as Well as the Mixed Biofilm Formed on the Surface.

To assess the effect of hygiene protocols and time on the physical-mechanical properties and colony-forming units (CFU) of Candida albicans, Staphylococcus aureus, and Streptococcus mutans on 3D-printed denture resins (SmartPrint and Yller) with extrinsic pigmentation compared to conventional resin (CR). The protocols were evaluated: brushing (B), brushing and immersion in water (W), 0.25% sodium hypochlorite (SH), and 0.15% triclosan (T), simulating 0, 1, 3, and 5 years. The data were analyzed by ANOVA with repeated measurements, ANOVA (Three-way) and Tukey's post-test, generalized linear model with Bonferroni adjustment, and ANOVA (Two-way) and Tukey's post-test (α = 0.05). The protocols influenced color (p = 0.036) and Knoop hardness (p < 0.001). Surface roughness was influenced by protocols/resin (p < 0.001) and time/resin (p = 0.001), and flexural strength by time/protocols (p = 0.014). C. albicans showed interactions with all factors (p = 0.033). Staphylococcus aureus was affected by protocols (p < 0.001). Streptococcus mutans exhibited no count for SH and T (p < 0.001). Yller resin showed more color changes. The 3D-printed resins displayed lower microhardness, increased roughness, and decreased flexural strength compared to CR with all protocols in a simulated period of 5 years. The indication of printed resins should be restricted to less than 3 years.

Risk factors and immunological biomarkers in denture stomatitis: An observational cross-sectional study.

OBJECTIVE: Assess risk factors, local and systemic immunological biomarkers in healthy individuals and with Denture Stomatitis (DS). DESIGN: For this observational transversal study, 27 participants without DS (Group 0), 24 with moderate DS (Group 1), and 25 with severe DS (Group 2) were assessed for sociodemographic, behavioral, and clinical parameters, microbial load of Candida spp., Staphylococcus spp., Streptococcus mutans, Pseudomonas spp., and enterobacteria, and cytokine and C-reactive protein levels. ANOVA, Fisher's exact, Kruskal-Wallis, Mann-Whitney, Wilcoxon and Pearson's chi-square tests were used for data analysis (α = 0.05). RESULTS: Group 1 had a significantly higher mean age compared to the other groups (P = 0.018), but no correlation was identified between age and DS (P = 0.830; r = 0.025). No significant differences were found among the groups for other sociodemographic and behavioral characteristics. Group 1 had significantly older upper and lower dentures; however, no correlation was identified between age of upper (P = 0.522; r = 0.075) and lower (P = 0.143; r = 0.195) dentures and DS. The microbial load of Candida albicans on the dentures (P = 0.035) and Candida spp. on the palate (P = 0.008) of the groups 1 and 2 was higher than group 0. Group 1 and 2 had higher Candida spp. counts on denture (P = 0.003) than group 0. There was no difference among groups for bacterial analyzed. Group 1 showed higher and Group 2 intermediate salivary levels of IL-6 compared to Group 0. There was no difference in the C-reactive protein levels among groups. CONCLUSIONS: Microbial load of Candida spp. is the factor with the strongest relationship with DS, with capacity for local signaling through IL-6.

The long-term effect of sub-boiling water on dental unit waterlines and its ability to control cross-contamination in dentistry.

This study investigated the effect of water at high temperature on the physical and mechanical properties of polyurethane and on biofilm removal, aiming for its applicability in dental unit waterlines. The evaluations were carried out after simulating a 1-year period of daily immersion and measured changes in color, microhardness, surface roughness, and tensile strength before and after reproducing a disinfection protocol. For antibiofilm activity measurement, fragments of waterline were contaminated with Pseudomonas aeruginosa and submitted to the disinfection protocols. Relative to effects on the physical and mechanical properties, immersion in water at 60°C did not promote changes in color and tensile strength. However, lower values were observed for microhardness and increased values for surface roughness. Regarding antibiofilm action, water at 60°C significantly reduced the microbial load and promoted substantial changes in cells morphology. In conclusion, disinfection with water at 60°C demonstrated possible application in controlling cross-contamination in dentistry.

Antimicrobial effect of phytosphingosine in acrylic resin

Abstract This study evaluated color stability (CS), anti-adherence effect (AAE), and cell viability of microorganisms on acrylic resin (AR) surface, treated associated or not with sodium percarbonate (SP). AR specimens were prepared, and color analysis was performed before and after the treatments and the CS was calculated. For analysis of AAE, the samples were sterilized by radiation in a microwave oven. Then samples were randomly distributed: phosphate-buffered saline (PBS - control), 0.5% sodium hypochlorite (SH), phytosphingosine (PHS), and phytosphingosine + SP (PHS+Na2CO3). The specimens remained in contact with solutions for 30 minutes and were later contaminated by Candida albicans. Aliquots were seeded in Petri dishes with Sabouraud Dextrose agar and incubated at 37°C for 24 hours. After the incubation, the number of colonies was counted. The cell viability of adhered microorganisms on the AR was evaluated and 20 fields were observed under an epifluorescence microscope, and the percentage of adhered viable cells was calculated. Data were compared (One-way ANOVA, Tukey, p<.05). As for CS, PHS+ Na2CO3 (0.4±0.1) resulted in less change than PBS (0.9±0.2), similar to the other groups (SH [1.0±0.3)]; PHS [0.9±0.2)]). There was no difference for all tested solutions regarding the ability to avoid microorganism adherence (p>0.05), but PHS (11.2±4.1) resulted in a smaller area of adhered viable cells, statistically different from SH (18.2±7.6) and PBS (26.4±10.8). It was concluded that PHS resulted in lower adhered viable cells and when associated with Na2CO3, also shows a lower effect on the CS of AR.

Resumo Este estudo avaliou estabilidade de cor (EC), efeito antiaderente (EAA) e viabilidade celular de microrganismos em superfície de resina acrílica (RA), tratada com solução de fitoesfingosina, associada ou não ao percarbonato de sódio (PS). Espécimes RA foram preparados e análise de cor foi realizada antes e após os tratamentos e EC foi calculada. Para análise de EAA, as amostras foram esterilizadas por radiação em forno de micro-ondas. Então foram distribuídas aleatoriamente: solução salina tamponada com fosfato (PBS - controle), hipoclorito de sódio 0,5% (SH), fitoesfingosina (PHS) e fitoesfingosina + SP (PHS+Na2CO3). Os espécimes permaneceram em contato com as soluções por 30 minutos e posteriormente foram contaminados por Candida albicans. Alíquotas foram semeadas em placas de Petri com ágar Sabouraud Dextrose e incubadas a 37°C por 24 horas. Após a incubação, o número de colônias foi contado. A viabilidade celular dos microorganismos aderidos na RA foi avaliada e 20 campos foram observados em microscópio de epifluorescência, e a porcentagem de células viáveis aderidas foi calculada. Os dados foram comparados (One-way ANOVA, Tukey, p<0,05). Quanto a EC, o PHS+ Na2CO3 [0,4 (0,1)] resultou em menor alteração que o PBS [0,9 (0,2)], semelhante aos demais grupos (SH [1,0 (0,3)]; PHS [0,9 (0,2)]). Não houve diferença para todas as soluções testadas quanto à capacidade de evitar a aderência de microorganismos (p>0,05), mas o PHS [11,2 (4,1)] resultou em uma área menor de células viáveis aderidas, estatisticamente diferente do SH [18,2 (7,6)] e PBS [26,4 (10,8)]. Concluiu-se que o PHS resultou em menor número de células viáveis aderidas e, quando associado ao Na2CO3, também apresenta menor efeito sobre o EC da RA.

In vitro antibacterial activity of green tea-loaded chitosan nanoparticles on caries-related microorganisms and dentin after Er:YAG laser caries removal.

This study aimed to determine the inhibitory effects of green tea (Gt), EGCG, and nanoformulations containing chitosan (Nchi) and chitosan+green tea (Nchi+Gt) against Streptococcus mutans and Lactobacillus casei. In addition, the antibacterial effect of nanoformulations was evaluated directly on dentin after the selective removal of carious lesion. At first, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against S. mutans and L. casei isolates were investigated. In parallel, dentin specimens were exposed to S. mutans to induce carious lesions. Soft dentin was selectively removed by Er:YAG laser (n=33) or bur (n=33). Remaining dentin was biomodified with Nchi (n=11) or Gt+Nchi (n=11). Control group (n=11) did not receive any treatment. Dentin scraps were collected at three time points. Microbiological analyses were conducted and evaluated by agar plate counts. Gt at 1:32 dilution inhibited S. mutans growth while 1:16 was efficient against L. casei. EGCG at 1:4 dilution completely inhibited S. mutans and L. casei growth. Independently of the association with Gt, Nchi completely inhibited S. mutans at 1:4 dilution. For L. casei, different concentrations of Nchi (1:32) and Nchi+Gt (1:8) were required to inhibit cell growth. After selective carious removal, viability of S. mutans decreased (p<0.001), without difference between bur and Er:YAG laser (p>0.05). Treatment with Nchi and Nchi+Gt did not influence the microbial load of S. mutans on dentin (p>0.05). Although variations in concentrations were noticed, all compounds showed antibacterial activity against S. mutans and L. casei. Both bur and Er:YAG laser have effectively removed soft dentin and reduced S. mutans counts. Nanoformulations did not promote any additional antibacterial effect in the remaining dentin.

Action of chitosan-based solutions against a model four-species biofilm formed on cobalt-chromium and acrylic resin surfaces.

OBJECTIVE: To evaluate the anti-biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans. BACKGROUND: Biofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation. MATERIALS AND METHODS: The anti-biofilm action of the experimental chitosan-based solutions and Nitradine™ was evaluated on acrylic resin and cobalt-chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology. RESULTS: Only chitosan reduced the viability of C. albicans on cobalt-chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan-based solutions neither promoted substantial alteration of the metabolic activity of the four-species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells. CONCLUSION: Although chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four-species biofilm from the Co-Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Antimicrobial Activity of Experimental Chitosan Solutions on Acrylic Resin and Cobalt-Chromium Surfaces.

PURPOSE: To evaluate the application of chitosan as a cleanser in the control of biofilm formation on cobalt-chromium (Co-Cr) alloy and acrylic resin surfaces. MATERIALS AND METHODS: In total, 172 Co-Cr discs and 172 acrylic resin discs (14 mm x 3 mm) were contaminated with Streptococcus mutans, Staphylococcus aureus, Candida albicans, or Candida glabrata and incubated for 48 hours. Then, specimens were randomly divided into groups and immersed in the following solutions for 15 minutes: solution without chitosan (WC/control); chitosan solution (CH: 5 mg/mL); chitosan nanoparticle solu.on (CN: 3.8 mg/mL); and effervescent tablet (ET). Biofilm recovery rates (n = 9) were evaluated by counting the colony-forming units (CFU/mL). Biofilm morphology was evaluated using scanning electron microscopy (SEM). Data were compared using the Kruskal-Wallis or ANOVA tests followed by the Tukey post hoc test. RESULTS: For acrylic resin, ET showed the lowest number of CFU for S aureus and S mutans (P < .001). CH exhibited intermediate values for S mutans, S aureus, and C albicans; CN exhibited intermediate values for S mutans and S aureus. For C glabrata, there was no sta.s.cal difference between the solu.ons (P = .264). For Co-Cr, ET showed the highest level of antimicrobial action against all microorganisms (P < .001), and CH showed an intermediate level of action against S mutans and S aureus. Against C albicans and C glabrata, there was no significant difference among CH, CN, and WC. CONCLUSIONS: Although ET had a broader spectrum of antimicrobial action, CH showed promise as a denture cleanser. Int J Prosthodont 2023;36:e61-e73.

Comparative analysis of Candida spp. isolated from complete denture wearers with and without an HIV diagnosis.

STATEMENT OF PROBLEM: Denture-related stomatitis (DRS), an inflammation frequently present in human immunodeficiency virus-positive (HIV+) individuals, can be attributable to colonization by Candida spp., which is considered a main factor. The virulence factors of these species are often modulated by the systemic condition of their hosts. PURPOSE: The purpose of this clinical study was to evaluate the incidence, virulence, and morphology of Candida spp. isolated from biofilms of complete denture wearers with DRS, with and without an HIV diagnosis. In addition, the interaction of the systemic condition with the ability of Candida spp. to colonize was evaluated. MATERIAL AND METHODS: Fifty-five complete denture wearers diagnosed with DRS were divided into 2 groups: experimental (HIV+) and control (human immunodeficiency virus-noninfected participants [HIV-]). Biofilm was collected by a standardized method of ultrasonification of prostheses. The incidence was evaluated by a chromogenic method and polymerase chain reaction (PCR). The virulence factors were assessed by using the capacity for biofilm formation by counting colony-forming units (CFUs/mL), biofilm metabolism by tetrazolium salt metabolization, and proteinase and phospholipase production by using a fluorimetric kit. Morphology was verified by using the hyphae-inducing test, and participants' health data were collected with a form. Data were analyzed by using the Student t, Mann-Whitney U, Spearman, and Fisher tests (α=.05). RESULTS: The results of incidence were related to 55 participants (22 experimental and 33 control); in total, 63 Candida spp. samples were isolated, showing 28 Candida albicans and 36 nonalbicans strains. No significant difference was found between groups in baseline CFU/mL counts, biofilm formation capacity, cell metabolism, and phospholipase production. Proteinase production was higher for C. albicans in the control (P=.031) and for nonalbicans in the experimental (P=.016) groups. Relative to health data, the experimental group showed a moderate negative correlation between the CFU count/mL at baseline for nonalbicans and DRS classification (P=.020). CONCLUSIONS: C. albicans was the most prevalent species. No difference was found in the Candida spp. of complete denture wearers with DRS, with and without an HIV diagnosis, with regard to virulence factors (except for proteinase production) and morphology.

Relation between the risk factors for the severity of denture stomatitis and quality of life of complete edentulous individuals: a cross-sectional study

Abstract Objective To assess the association between risk factors for developing denture stomatitis (DS) and oral health-related quality of life (OHRQoL) in complete denture wearers. Methodology Participants of both sexes, wearing complete dentures, were classified using the modified Newton classification for the absence or the severity of DS and allocated to groups Normal or zero, IA, IB, II, and III. Lifestyle, oral and denture history, and medication use were assessed using specific questionnaires; clinical parameters such as anatomical characteristics of support were evaluated with the Kapur classification; salivary flow (SF) was calculated by the volume of unstimulated saliva per minute; and microbial load was determined by counting colony forming units (CFU) of target microorganisms present in the biofilm collected from dentures and palate. OHIP-EDENT assessed the OHRQoL. Kendall's tau_b and Spearman tests were applied with a significance level of 5%. Results 184 patients (143 female and 41 male) aged 65.5 ± 6.8 years were evaluated. Positive correlations were found for sex (women; p=0.013, r=0.16), individuals who started to consume alcoholic beverages as a young adult (18-27 years) (p=0.008, r=0.22), CFU of Candida spp. (p<0.001, r=0.27 denture; p<0.001, r=0.31 palate); Candida albicans (p=0.004, r=0.22 denture; p=0.003, r=0.25 palate), and Candida glabrata (p=0.004, r=0.22 denture; p=0.001, r=0.27 palate). Moreover, negative correlations with DS were found for CFU of Staphylococcus spp. (p=0.004, r=-0.20 palate) and enterobacteria (p=0.002, r=-0.24 palate), as well as a negative correlation between SF (p=0.009, r=-0.193) and DS. The CFU of Staphylococcus spp. and enterobacteria on the palate significantly correlated with OHRQoL. Conclusion Being female, consuming alcoholic beverages as a young adult, CFU of Candida spp., Candida albicans, Candida glabrata, and salivary flow may be the most significant risk factors for DS. The microbial load of Staphylococcus spp. and enterobacteria seems to influence the quality of life for complete denture wearers.

Protocol with non-toxic chemicals to control biofilm in dental unit waterlines: physical, chemical, mechanical and biological perspective.

Biosafety in dentistry aims to combat cross-contamination and biofilm in dental unit waterlines. The aim was to investigate from a physical, chemical, mechanical and biological perspective, a protocol for using chemical products (citric acid, sodium bicarbonate and sodium chloride) to improve and maintain water quality in dental unit waterlines. Change in microhardness and corrosion tendency were observed in stainless steel samples. On the polyurethane surfaces, there were changes in color, microhardness and roughness. Anti-biofilm evaluations revealed a significant reduction in the biofilm biomass, metabolic activity and residual biofilm. These findings suggest that the protocol analyzed in this study showed an innovative potential against biofilm in dental unit waterlines, preserving the physical, chemical and mechanical properties of the materials.

Influence of glucose supplementation on biofilm formation of Candida albicans and Candida glabrata isolated from diabetic and non-diabetic individuals.

OBJECTIVE: This study evaluated the effect of different glucose concentration on biofilm formation of Candida albicans and Candida glabrata strains isolated from diabetic and non-diabetic individuals. METHODS: The study was divided into two stages: (I) selection and identification of 48 C. albicans and C. glabrata strains by polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR/RFLP); (II) evaluation of biofilm formation by means of viability rates (colony-forming units), biofilm dry matter (mg) and biofilm-covered areas (µm2). Statistical comparisons were performed through nonparametric analysis of longitudinal data in factorial experiments with pairwise comparisons using Friedman Conover's test (α = 0.05). RESULTS: All the Candida spp. had their identifications confirmed by PCR/RFLP. C. albicans biofilm of strains from diabetic individuals cultivated in different glucose concentration showed higher viability rates than strains from non-diabetic individuals. No difference was observed on viability of C. glabrata biofilm. Regarding biofilm dry matter, C. albicans biofilm of strains from diabetic individuals cultivated in different glucose concentration showed lower amount in weight than strains from non-diabetic individuals. In C. glabrata strains, this result was only observed in biofilms cultivated with no glucose supplementation. With regard to biofilm-covered areas, only glucose supplementation and non-diabetic condition showed a positive effect on C. albicans biofilm development, and no condition affected C. glabrata biofilm formation. CONCLUSION: The strain type (C. albicans and C. glabrata) isolated from diabetic and non-diabetic individuals influenced on biofilm formation, but glucose supplementation did not.

Clinical study of the biofilm of implant-supported complete dentures in healthy patients.

OBJECTIVE: The purpose of this study was to quantify the area covered by biofilm and identify bacteria and yeasts present in mandibular acrylic resin full-arch implant-supported fixed prostheses. BACKGROUND: Biofilm control of implant-supported fixed prosthesis is hampered by their design, and it can cause oral and systemic problems, mainly in immunocompromised patients like the elder. Knowledge about microbiota reinforces the awareness about the need for periodic professional cleaning maintenance. MATERIALS AND METHODS: Twenty prostheses were unscrewed, washed in 0.89% sodium chloride, stained with eosin 1% and photographed. The area covered by biofilm was digitally delimited and quantified. Biofilm samples were collected, diluted up to 1:107 , seeded in chromogenic agar media and incubated for 48 hours, at 37°C, for counting of colony-forming units (CFU/mL). DNA hybridization was performed to complement the identification and quantification of microorganisms. Data were analyzed using Mann-Whitney test, Spearman correlation and Fisher's exact test (α = .05). RESULTS: An average of 62% of the gingival surface of the prostheses was covered by biofilm. Enterococcus spp. (5.82 ± 1.38 log10 CFU/mL) and Staphylococcus aureus (5.75 ± 2.02 log10 CFU/mL) showed higher prevalence in cultures. Patients with five implants had less biofilm compared to those with four implants (P = .031) but had higher Escherichia coli counts (P = .039). In DNA hybridization, Streptococcus pneumoniae, Veillonella parvula and Fusobacterium nucleatum presented higher quantification and were present in all the samples; patients over 65 years old contained more Candida tropicalis (P = .049); prostheses on five implants presented lower quantification for several species. CONCLUSION: Biofilm was present on all prostheses, containing potentially pathogenic microorganisms. The number of implants may play a role in quantification of biofilm and in microorganism counts.

Increased diversity, fungal burden, and virulence of oral Candida spp. in patients undergoing anti-tuberculosis treatment.

Some studies have demonstrated a high prevalence of Candida species in patients with tuberculosis (TB). This is most likely due to long-term antimicrobial therapy. To date, no longitudinal studies addressed the effects of anti-TB treatment on the fungal burden and virulence of Candida spp. This study investigated the prevalence and virulence of Candida spp. in the oral cavity of 30 TB patients at different stages of treatment through a cohort study. These results were compared with those of 60 systemically healthy individuals in a cross-sectional study. Oral rinse samples from TB patients were collected before 45 and after 120 days of treatment. In the control group, the biological samples were collected only once. Candida spp. were identified by restriction fragment length polymorphism (RFLP) assays, and the following virulence factors were studied: phospholipase C and proteinase production, as well as Candida spp. biofilm and hyphae formation. The clinical diagnosis of TB and its treatment time were associated with the greater fungal burden (p < 0.0001), presence of non-albicans Candida (NAC) species (p = 0.0003), and increased virulence factors when compared with the Candida spp. isolated from systemically healthy individuals. The results showed that anti-TB treatment time was responsible for the increased fungal burden and isolation of NAC in TB patients (p = 0.0233). The increased prevalence, quantification, and virulence of Candida spp. isolated from the oral cavity of TB patients highlight the greater risk of oral lesions and cases of systemic dissemination in these patients.

Complete denture hygiene solutions: antibiofilm activity and effects on physical and mechanical properties of acrylic resin.

BACKGROUND: Appropriated denture hygiene is a predictive factor for longevity of rehabilitation treatment and maintenance of the oral mucosal health. Although, disinfectant solutions are commonly used as denture cleansers, the impact of these solutions on acrylic resin-based dentures remain unclear. OBJECTIVE: To evaluate, in vitro, the antibiofilm activity of complete denture hygiene solutions and their effects on physical and mechanical properties of acrylic resin. METHODOLOGY: For antibiofilm activity measurement acrylic resin specimens were contaminated with Candida albicans, Candida glabrata and Streptococcus mutans. After biofilm growth, the specimens were assigned to the hygiene solutions: Distilled water (Control); 0.2% Sodium hypochlorite (SH); Efferdent Power Clean Crystals (EPC) and 6.25% Ricinus communis (RC). The viability of microorganisms was evaluated by agar plate counts. In parallel, physical, and mechanical properties of the acrylic resin were evaluated after simulating a 5-year period of daily immersion in the previously mentioned solutions. The changes in surface roughness, color, microhardness, flexural strength, impact strength, sorption and solubility were evaluated. Data were compared by ANOVA followed by the Tukey test or Kruskal-Wallis followed by the Dunn test depending on the distribution (α=0.05). RESULTS: Regarding antibiofilm action, SH eliminated all microorganisms while EPC and RC exhibited moderate action against S. mutans (p=0.001) and C. glabrata (p<0.001), respectively. Relative to effects on the physical and mechanical properties of the acrylic resin, RC led to higher values of color change (p=0.030), hardness (p<0.001), surface roughness (p=0.006) and flexural strength (p<0.001). Moreover, RC induced the highest values of changes in solubility (p<0.001). EPC promoted greater changes in surface morphology, whereas immersion in SH retained the initial appearance of the acrylic resin surface. All hygiene solutions reduced the impact strength (p<0.05). CONCLUSION: SH presented the most effective antibiofilm activity. In addition, changes on properties were observed after immersion in RC, which were considered within acceptable limits.

Action of disinfectant solutions on adaptive capacity and virulence factors of the Candida spp. biofilms formed on acrylic resin.

BACKGROUND: Understanding the behavior of Candida spp. when exposed to denture disinfectants is essential to optimize their effectiveness. Changes in the virulence factors may cause increased resistance of Candida spp. to disinfectant agents. OBJECTIVE: To evaluate the microbial load, cellular metabolism, hydrolytic enzyme production, hyphae formation, live cell and biofilm quantification of Candida albicans, Candida tropicalis and Candida glabrata after exposure to disinfectant solutions. METHODOLOGY: Simple biofilms were grown on heat-polymerized acrylic resin specimens, and divided into groups according to solutions/strains: distilled water (control); 0.25% sodium hypochlorite (NaOCl 0.25% ); 10% Ricinus communis (RC 10%); and 0.5% Chloramine T (CT 0.5%). The virulence factors were evaluated using the CFU count (microbial load), XTT method (cell metabolism), epifluorescence microscopy (biofilm removal and live or dead cells adhered), protease and phospholipase production and hyphae formation. Data were analyzed (α=0.05) by one-way ANOVA/ Tukey post hoc test, Kruskal-Wallis test and Wilcoxon test. RESULTS: NaOCl 0.25% was the most effective solution. CT 0.5% reduced the number of CFUs more than RC 10% and the control. RC 10% was effective only against C. glabrata. RC 10% and CT 0.5% decreased the cellular metabolism of C. albicans and C. glabrata. Enzyme production was not affected. Hyphal growth in the RC 10% and CT 0.5% groups was similar to that of the control. CT 0.5% was better than RC 10% against C. albicans and C. tropicalis when measuring the total amount of biofilm and number of living cells. For C. glabrata, CT 0.5% was equal to RC 10% in the maintenance of living cells; RC 10% was superior for biofilm removal. CONCLUSIONS: The CT 0.5% achieved better results than those of Ricinus communis at 10%, favoring the creation of specific products for dentures. Adjustments in the formulations of RC 10% are necessary due to efficacy against C. glabrata. The NaOCl 0.25% is the most effective and could be suitable for use as a positive control.