Bacteriological Evaluation of Gingival Crevicular Fluid in Teeth Restored Using Fixed Dental Prostheses: An In Vivo Study.

The present in vivo study determined the microbiological counts of the gingival crevicular fluid (GCF) among patients with fixed dental prostheses fabricated using three different techniques. A total of 129 subjects were divided into three study groups: first, cobalt-chrome-based, metal-ceramic prostheses fabricated by the conventional method (MC, n = 35); the second group consisted of cobalt-chrome-based, metal-ceramic prostheses fabricated by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (CC-MC, n = 35); the third group comprised zirconia-based ceramic prostheses fabricated using the CAD/CAM technique (CC-Zr, n = 35). The control consisted of 24 patients using prostheses fabricated with either MC, CC-MC, or CC-Zr. The GCF was obtained from the subjects before treatment, and 6 and 12 months after the prosthetic treatment. Bacteriological and bacterioscopic analysis of the GCF was performed to analyze the patients' GCF. The data were analyzed using SPSS V20 (IBM Company, Chicago, IL, USA). The number of microorganisms of the gingival crevicular fluid in all groups at 12 months of prosthetic treatment reduced dramatically compared with the data obtained before prosthetic treatment. Inflammatory processes in the periodontium occurred slowly in the case of zirconium oxide-based ceramic constructions due to their biocompatibility with the mucous membranes and tissues of the oral cavity as well as a reduced risk of dental biofilm formation. This should be considered by dentists and prosthodontists when choosing restoration materials for subjects with periodontal pathology.

Nanopartículas de prata em bases de próteses de PMMA para controle de atividade microbiana / Silver nanoparticles in PMMA prosthesis bases to control microbial activity

Objetivo:Avaliar in vitro a atividade de Staphylococcus aureus e Candida albicans em bases de próteses convencionais à base de polimetilmetacrilato de metila com nanopartículas de prata incorporadas a sua composição. Métodos: Foi realizado um estudo experimental laboratorial com resinas acrílicas autopolimerizáveis comercialmente disponíveis, Vipi Flash/VIPI e JET/Clássico. Foram confeccionados 80 corpos de prova, divididos em 16 grupos (n = 5), referentes ao tipo de resina, tratamento (incorporação e imersão na solução de nanopartículas de prata) e microrganismo inoculado. As nanopartículas foram sintetizadas com ácido polimetacrílico, nitrato de prata e irradiadas com luz ultravioleta de baixa potência (~8W) por 6 horas, e as suas concentrações idealizadas pelo método de microdiluição em placas para determinação da concentração mínima inibitória frente aos microrganismos selecionados. Verificou-se ação bactericida e fungicida com concentração inicial de 25% e após fator de diluição 12,5%. Resultados: Houve dificuldade de incorporação das nanopartículas na resina acrílica, que pode decorrer da alteração da proporção 3:1 recomendada pelo fabricante ou pela redução ou inativação da ação da nanopartícula de prata pela interação com o polimetilmetacrilato. VIPI com inclusão de nanopartícula obteve menor aderência de biofilme de Candida albicans. Conclusão:A nanopartícula de prata mostrou-se eficaz na sua ação de controle de Candida albicans e Staphylococcus aureus no método de imersão, entretanto, a sua ação antimicrobiana foi comprometida após inclusão nas resinas acrílicas.

Aim:To perform an in vitro evaluation of the activity of Staphylococcus aureus and Candida albicansin conventional prosthesis bases, based on methyl polymethylmethacrylate with silver nanoparticles incorporated into the composition. Methods: An experimental laboratory study was carried out using commercially available self-curing acrylic resins, Vipi Flash/VIPI and JET/Clássico. Eighty specimens were manufactured and divided into 16 groups (n = 5), referent to the resin brand, treatment (incorporation and immersion in the silver nanoparticle solution), and inoculated microorganism. The nanoparticles were synthesized with polymethacrylic acid and silver nitrate, and were irradiated with a low power (~ 8W) ultraviolet light for 6 hours. Their concentrations were idealized by the method of microplate dilution to determine the minimum inhibitory concentration when compared to the selected microorganisms. Bactericidal and fungicidal activities were identified with an initial concentration of 25% and a subsequent dilution factor of 12.5%. Results:It was difficult to incorporate the AgNPs into the acrylic resin, which may well have resulted from the change from the 3:1 proportion recommended by the manufacturer or by reducing or inactivating the action of the silver nanoparticle by interaction with polymethylmethacrylate. VIPI with the inclusion of nanoparticles obtained a lesser Candida albicans biofilm adherence. Conclusion: Silver nanoparticles were effective in controlling Candida albicans and Staphylococcus aureus in the immersion method; however, the antimicrobial activity was compromised after inclusion in acrylic resins.

Hyposalivation, oral health, and Candida colonization in independent dentate elders.

Hyposalivation is an important problem in elders and could interfere with several oral functions and microbial ecology. While the number of independent elders who retain more natural teeth increases worldwide, few studies examined hyposalivation in this population. Thus, this study aims to examine relationships between hyposalivation, oral health conditions and oral Candida colonization in independent dentate elders and evaluate factors associated with salivary flow and Candida carriage. We conducted a cross-sectional study in fifty-three dentate elders (≥65 years old with at least 4 pairs of posterior occlusal contacts) with no, or well-controlled, systemic conditions. Participants were interviewed for medical history, subjective dry mouth symptoms, oral hygiene practices and denture information. Unstimulated and stimulated salivary flow rates, objective dry mouth signs, gingival, tongue-coating, and root-caries indices were recorded. Stimulated saliva was cultured on Sabouraud-dextrose agar for Candida counts. Candida species were identified using chromogenic Candida agar and polymerase chain reaction. Statistical significance level was set at p<0.05. The results showed that hyposalivation was associated with higher gingival and tongue-coating indices (p = 0.003 and 0.015, respectively), but not root-caries index. Hyposalivation was also associated with higher prevalence of oral Candida colonization (p = 0.010; adjusted OR = 4.36, 95% confidence interval = 1.29-14.72). These two indices and Candida load were negatively correlated with unstimulated and stimulated salivary flow rates. Interestingly, non-albicans Candida species were more prevalent in denture wearers (p = 0.017). Hence, hyposalivation is a risk factor for poorer oral health and oral Candida colonization in independent dentate elders. Because of its potential adverse effects on oral and systemic health, hyposalivation should be carefully monitored in elders.

Efeito do extrato da própolis e do digluconato de clorexidina sobre a formação de biofilme por Candida albicans em resina acrílica / Effect of propolis extract and chlorhexidine digluconate on the biofilm formation by Candida albicans in acrylic resin

Objetivo: avaliar in vitro a ação antimicrobiana do extrato da própolis (EP) e do digluconato de clorexidina (DCHX) na formação de biofilme por Candida albicans em resina acrílica termopolimerizada. Métodos: o efeito do EP e DCHX em biofilmes de C. albicans foi avaliado pela quantificação de Unidades Formadoras de Colônias (UFCs), pela quantificação da biomassa por cristal violeta e de polissacarídeos por safranina. Para tanto, C. albicans foram pré-aderidas em corpos de prova e somente em microplacas de poliestireno, posteriormente foi realizado o tratamento com diferentes concentrações de EP (221 µg/mL e 443 µg/mL) e DCHX (0,25% e 0,5%). Resultados: foi demonstrada uma redução significativa na formação de biofilme por C. albicans com ambas as substâncias testadas e em todas as concentrações. Conclusão: de acordo com os resultados, observou-se que ambos os tratamentos foram eficazes na redução do biofilme e que o EP, por ser um produto natural, de baixo custo e sem afeitos colaterais, representa uma alternativa inovadora para o tratamento da candidose oral em usuários de próteses removíveis.(AU)

Objective: to evaluate in vitro the antimicrobial action of propolis extract (EP) and chlorhexidine digluconate (DCHX) in the biofilm formation by Candida albicans in thermopolymerized acrylic resin. Methods: the effect of EP and DCHX on C. albicans biofilms were evaluated through the quantification of Colony Forming Units (CFU's), the quantification of biomass by violet crystal and polysaccharides by safranin. For this purpose, C. albicans were pre-adhered to specimens and only on polystyrene microplates and subsequently the treatment was performed with different concentrations of EP (221 µg/mL and 443 µg/mL) and DCHX (0.25% and 0,5%). Results: a significant reduction in the biofilm formation by C. albicans was demonstrated, with both substances tested and in all concentrations. Conclusion: according to the results, it was observed that both treatments were effective in reducing biofilm and EP, being a natural product, low cost and without side effects, represents an innovative alternative for the treatment of oral candidiasis in users removable dentures.(AU)

A 3D printed microfluidic flow-cell for microscopy analysis of in situ-grown biofilms.

Biofilm phenomena ranging from metabolic processes to attachment, detachment and quorum sensing are influenced by the fluid flow across the biofilm. A number of commercially available flow-cells allow for microscopy analysis of laboratory biofilms under flow, but there is a lack of shear controlled microfluidic devices that accommodate biofilms grown in situ on carriers or tissue samples. Therefore, we developed a flow-cell with adjustable geometry for microscopy analysis of in situ-grown biofilm samples under shear-controlled flow. The flow-cells were designed as one-piece disposable models, 3D-printed in resin and sealed with a coverslip after insertion of the biofilm sample. As a proof of concept, we studied the impact of stimulated saliva flow on pH developments in in situ-grown dental biofilms exposed to sucrose. Under static conditions, pH dropped in the biofilms, with pronounced differences between individual biofilms, but also between different microscopic fields of view within one biofilm. pH in the top layer of the biofilms tended to be lower than pH in the bottom layer. Under conditions of stimulated saliva flow (5 mm/min), pH rose to neutral or slightly alkaline values in all biofilms, and the vertical gradients were reversed, with the biofilm bottom becoming more acidic than the top. Hence, the present work demonstrates the importance of flow for the study of pH in dental biofilms.

Oral Biofilm on Dental Materials Among Khat Chewers.

BACKGROUND: Nowadays khat chewing habit is increasing among population in southern part of Saudi Arabia, Jazan and till date there is no literature investigating the effect of khat on oral biofilm on dental materials. OBJECTIVE: To evaluate and compare the bacterial biofilm on different types of dental restorative materials used in replacing missing tooth structures among khat chewers and non-khat chewers. MATERIALS AND METHODS: Hundred and twenty biofilm samples were collected from different dental restorations, such as All-ceramic (AL), Metal Ceramic (MC), Metal crowns or bridges (M), Composite (C), Glass Ionomer (GI) and Amalgam (A) restorations in non-khat and khat chewers (K). DNA extraction was done and subjected to PCR. Bacterial species, such as Streptococcus, Neisseria, Bacillus, Granulicatella and Veillonella were identified and counted. PCR products were also sequenced to detect similarity. Association between bacterial type and dental materials among non-khat and khat chewers were tested with Chi-Square test (Fishers Exact test). RESULTS: The frequency and percentage of Streptococcus species were marginally higher among khat chewers (42; 70%) compared with non-khat chewers (38; 63.3%) group. But the Veillonella species were higher among non-khat chewers (9: 15%), compared to the khat chewers group (7; 11.7%). No statistically significant difference was detected among species in both groups. In non-khat and khat chewer group, the maximum hits were related to Streptococcus spp. in glass ionomer, amalgam, and composite (restorative materials), followed by metal ceramic and metal (prosthetic materials). Veillonella spp. showed maximum hits in the metal group among non-khat chewers and in all-ceramic among khat chewers. Statically significant differences were recorded among composite and amalgam samples with p values 0.047 and 0.036 in khat chewer group. CONCLUSION: Khat chewers showed statistically significant differences in oral biofilm in the composite and amalgam restorative materials, but there were no significant differences found among any materials and species between the groups.

Candida albicans biofilms on different materials for manufacturing implant abutments and prostheses

BACKGROUND: Morphological, physical and chemical properties of both implants and prostheses can determine the biofilm formation on their surface and increase the risk of biological complications. The aim of this study was to evaluate the capacity of biofilm formation of Candida albicans on different materials used to manufacture abutments and prostheses. MATERIAL AND METHODS: Biofilm formation was analyzed on cp grade II titanium, cobalt-chromium alloy and zirconia, silicone, acrylic resin (polymethylmethacrylate) and nano-hybrid composite. Some samples were partially covered with lithium disilicate glass ceramic to study specifically the junction areas. C. albicans was incubated in a biofilm reactor at 37 °C with agitation. The biofilm formation was evaluated at 24 and 48 hours. In addition, the morphology of the biofilm was evaluated by scanning electron microscopy. RESULTS: C. albicans developed biofilms on the surface of all materials tested. Cobalt-chromium alloy showed the lowest density of adhered biofilm, followed by zirconia and titanium. Silicone and resin showed up to 20 times higher density of biofilm. A higher biofilm formation was observed when junctions of materials presented micro-pores or imperfections. CONCLUSIONS: The biofilm formed in the three materials used in the manufacture of abutments and prostheses showed no major differences, being far less dense than in the resins. Two clinical recommendations can be made: to avoid the presence of resins in the subgingival area of implant prostheses and to design prostheses placing cobalt-chromium alloy/ceramic or titanium/ceramic junctions as far as possible from implants

No disponible

Cytotoxicity and antimicrobial effects of citronella oil (Cymbopogon nardus) and commercial mouthwashes on S. aureus and C. albicans biofilms in prosthetic materials.

Although the effectiveness of some mouthwashes has been proven, phytotherapy is still a field to be explored as an alternative to commercial products. OBJECTIVE: To evaluate, in vitro, the cytotoxicity and efficacy of two solutions based on citronella oil (CN), on S. aureus and C. albicans biofilms (in formation-adhesion phase and 24 h-biofilm formation) on acrylic resin and nickel-chromium alloy samples (one trademark of each material), compared to two alcohol-free commercial mouthwashes. MATERIAL AND METHODS: Two solutions containing CN at concentrations of 5x and 10x the minimum bactericidal/fungicidal concentration (MBC/MFC) were prepared by microdilution. After contamination of the samples surfaces with these microorganisms, the mouthwashes (CN - 5x and 10x; CHX - 0,12% alcohol-free chlorhexidine and LT - alcohol-free essential oils) were evaluated. Mouthwash simulation was performed for 1 min at two moments, the first simulation after 4 h of microbial adhesion and 24 h-biofilm formation, and the second simulation, 6 h after the first simulation. For biofilm quantification, the number of cultured cells was evaluated by CFUs. The cytotoxicity assay was performed on HaCat epithelial cells and quantified by the MTT method. RESULTS: Tested solutions completely inhibited the growth of both microorganisms in the adhesion phase. All solutions showed inhibitory activity against 24 h-biofilm formation. However, CN led to greater microbial reduction, regardless of the surface of the sample. All solutions demonstrated a toxic effect. However, after serial dilution, CN presented the lowest cytotoxic effect. CONCLUSION: Citronella had a lower cytotoxic effect and a higher action compared to commercial solutions.

Denture stomatitis associated with small-colony variants of Staphylococcus aureus: a case report.

BACKGROUND: The small-colony variants (SCVs) of Staphylococcus aureus were isolated from persistent and recurrent infections, especially after placement of medical devices having direct contact with human tissues. The emergence of SCVs is a survival strategy of S. aureus which enables them to hide inside host's cells and induces a less severe immune response than to wild-type S. aureus. However, contrary to other medical devices, dental prosthesis as a surface potentially colonized by SCVs of S. aureus has not been examined thus far. We reported the first case of SCVs - S. aureus infection in denture wearer. CASE PRESENTATION: A 62-year-old woman with a complete removable acrylic denture presented extensive elevated erythematous lesions on the palate, compatible with denture stomatitis. The patient had a history of arterial hypertension, cigarette smoking and wearing denture at night. The fungal colonies, identified as Candida albicans, were cultured on Sabouraud agar. From three swabs (from hard palate mucosa, denture surface and angular cheilitis lesions) were cultured of pinpoint, clear, non-pigmented, and non-haemolytic colonies on Columbia agar. The small colonies turned out to be Gram-positive cocci, catalase-, Pastorex Staph Plus -, and clumping factor-positive, and oxidase-negative. Suspected phenotypically SCVs forms were definitively identified as S. aureus based on PCR amplification of species specific nuc and coa genes. Methicillin-resistance was verified by mecA gene detection. The isolates turned out to be susceptible to methicillin (MSSA) and resistant to gentamicin. The isolate was identified as menadione-auxotrophic variant. CONCLUSIONS: This case demonstrated that oral cavity in denture wearers may be a reservoir of small-colony variants of S. aureus, besides C. albicans. The prevalence of these bacteria and their role in the pathogenesis of oral diseases are not understood. Due to problems with their detection and identification, the true prevalence of oral SCVs may be underestimated.

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.

The underestimated problem of oral Candida colonization-An observational pilot study in one nursing home.

Objectives: Older people are at increased risk of intraoral yeast colonization. In this observational case series, we assessed Candida colonization among nine nursing home residents to investigate possible correlations with their individual characteristics, general health parameters, and oral care. We also described the effect of professional dental cleaning (PDC) including prosthesis cleaning on colonization cases. Materials and methods: General clinical and oral health was assessed in nine residents, and samples were taken from six oral mucosa sites or prosthetic surfaces. PDC was performed to achieve macroscopically clean results, and residents were re-examined 2 weeks later. Results: We found that six residents were intraorally colonized with Candida albicans; four also had Candida glabrata. Prostheses were particularly infected. Dementia, multimorbidity, and presence of prostheses reduced oral hygiene ability; requiring assistance for oral hygiene care was a risk indicator for Candida colonization. PDC reduced C. albicans (at the expense of increased C. glabrata) but was not optimal for maintaining Candida reduction. Conclusion: In this pilot study, Candida colonization is prevalent among nursing home residents, especially those with cognitive impairment, multimorbidity, or reduced oral hygiene capacity. Potential negative effects on general health necessitate diagnostic and therapeutic guidelines. PDC alone did not maintain the reduction in Candida colonization; additional methods for daily oral care are necessary.

Influence of Dental Prosthesis and Restorative Materials Interface on Oral Biofilms.

Oral biofilms attach onto both teeth surfaces and dental material surfaces in oral cavities. In the meantime, oral biofilms are not only the pathogenesis of dental caries and periodontitis, but also secondary caries and peri-implantitis, which would lead to the failure of clinical treatments. The material surfaces exposed to oral conditions can influence pellicle coating, initial bacterial adhesion, and biofilm formation, due to their specific physical and chemical characteristics. To define the effect of physical and chemical characteristics of dental prosthesis and restorative material on oral biofilms, we discuss resin-based composites, glass ionomer cements, amalgams, dental alloys, ceramic, and dental implant material surface properties. In conclusion, each particular chemical composition (organic matrix, inorganic filler, fluoride, and various metallic ions) can enhance or inhibit biofilm formation. Irregular topography and rough surfaces provide favorable interface for bacterial colonization, protecting bacteria against shear forces during their initial reversible binding and biofilm formation. Moreover, the surface free energy, hydrophobicity, and surface-coating techniques, also have a significant influence on oral biofilms. However, controversies still exist in the current research for the different methods and models applied. In addition, more in situ studies are needed to clarify the role and mechanism of each surface parameter on oral biofilm development.

A comparative evaluation of the effect of phototherapy of fiber post on its bond strength to dental composite.

The aim of the study was to evaluate the effect of diode laser as a phototherapy on surface treatment of fiber post and its bond strength to resin core build-up material. In this in-vitro study fifty fiber post of 1 mm tip-diameter and 20 mm length were used. The posts were mounted and randomly divided into 5 groups (n = 10) according to different surface treatment methods i.e. Group 1: Control, Group 2: Application of 37% Phosphoric Acid, Group 3: Treated with 40% H2O2, Group 4: Sandblasted with 50 µm aluminium oxide particles and Group 5: treated with diode laser. In all specimens including control, a cylinder of resin composite around the fiber post was made. All Specimens were mounted in a universal testing machine. Push-out test was performed and bond strengths were calculated. Using analysis of variance (ANOVA) and post hoc Tukey multiple comparisons test, means of push out bond strength were compared among the study groups. The highest bond strength was shown among Sandblasted [50 µm, Aluminium Oxide (Al2O3)] group [139.86] and the lowest push-out bond strength was observed in Control specimens [75.73]. The bond strength values of fiber post treated with Diode laser [100.81] and 40% H2O2 [105.64] were comparable.

[Control of cross-contamination in dental prostheses laboratories in Galicia]. / Control de la infección cruzada en los laboratorios de prótesis dental de Galicia.

BACKGROUND: Dental laboratories are a potential source of cross-contamination. This study aims to assess its control in Galicia. METHODS: Voluntary random telephone interviews resulted in 149 completed questionnaires. The variables are described by percentages or means and standard deviations. A bivariate analysis was undertaken using the Chi square test. RESULTS: Participants were mostly middle-age (mean=45.7, SD=9.8) males (68.5%) with 20.8 (SD=10.5) years of professional experience in middle-size urban (58.4%) laboratories, who identified a higher risk when receiving items from the clinic (80.6%). Most technicians (57.7%) have a written protocol. Many (55.0%), significantly older males, do not check for item disinfection. Most technicians use gloves (62.4%) particularly younger staff at larger laboratories. Fifty-five point seven percent had been vaccinated against hepatitis B. Only 22.0% of technicians reported receiving training in cross-contamination control. CONCLUSIONS: Identified cross-infection control practices are below standards, and lack of training and protocols are a matter for concern.

Effect of Type II Diabetes Mellitus, Candida Albicans and Streptococcus Mutans on the Biofilm Formation on Prosthetic Materials.

AIM: To investigate the biofilm formation on Prosthetic materials as affected by type II diabetes mellitus, Candida albicans and Streptococcus mutans. MATERIALS AND METHODS: Two types of saliva, natural saliva, and artificial saliva were collected and prepared respectively. The natural saliva was divided into diabetic and non-diabetic saliva. The artificial saliva was further divided into two groups, one inoculated with Streptococcus mutans and the second with Candida albicans. The 150 samples of various prosthetic materials were prepared using nickel-chromium alloy, ceramic, soft liner, tooth molding powder; heat cured the acrylic resin. The samples were then immersed in natural saliva and artificial saliva and studied for biofilm formation. RESULTS: Diabetic saliva formed more biofilm than non-diabetic saliva. Streptococcus mutans were able to form more biofilm than Candida albicans in artificial saliva on constitutive androstane receptor (hCAR) and spinal length (SL). In Diabetic saliva, there was a significant difference in the biofilm formation seen between MC and NCA (p < 0.05). No biofilm was formed on hCAR in natural saliva (diabetic or non-diabetic). In artificial saliva inoculated with Candida albicans and streptococcus mutans there is a significant difference in the biofilm formation in all the materials except NCA. CONCLUSION: Diabetic saliva has more potential to form biofilm than non-diabetic saliva. Also, Candida albicans and Streptococcus mutans both can form a biofilm on materials used with the maximum formation on hCAR. Smoother materials formed less biofilm than rougher surfaces like hCAR, PCM, SL. CLINICAL SIGNIFICANCE: It is desirable for dental restorative materials to have a low susceptibility for accumulation and formation of biofilm as it may lead to pathologies such as dental caries, periodontal disease, peri-implantitis, etc. which are plaque-related. The most commonly used materials in prosthodontics have been used in the study to establish a direct relationship with the formation of biofilm, this, in turn, helps us to take the right call in choosing a material for a patient with an already compromised systemic condition.

The essential oil of Allium sativum as an alternative agent against Candida isolated from dental prostheses / Aceite esencial de Allium sativum como tratamiento alternativo contra aislamientos de Candida procedentes de prótesis dentales

Background. The colonization of the surfaces of dental prostheses by Candida albicans is associated with the development of denture stomatitis. In this context, the use of fluconazole has been proposed, but its disadvantage is microbial resistance. Meanwhile, the oil of Allium sativum has shown an effect in controlling biofilm formation by C. albicans. Aims. The objective of this study was to determine the antifungal activities of the essential oil of A. sativum and fluconazole against clinical isolates of Candida species obtained from rigid, acrylic-based partial or total dentures and to compare these agents’ effects on both biofilm and planktonic cells. Methods. A total of 48 clinical isolates obtained from the acrylic surface of partial or complete dentures were examined, and the following species were identified: C. albicans, Candida glabrata, Candida tropicalis, and Candida krusei. For each isolate, the antifungal activities of the essential oil of A. sativum and fluconazole against both biofilm and planktonic cells were evaluated using the Clinical & Laboratory Standards Institute (CLSI) M27-A3 method. The isolates were also evaluated by semiquantitative XTT reduction. Results. All planktonic Candida isolates were susceptible to the essential oil of A. sativum, whereas 4.2% were resistant to fluconazole. Regarding susceptibilities in biofilms, 43.8% of biofilms were resistant to A. sativum oil, and 91.7% were resistant to fluconazole. Conclusions. All planktonic cells of the different Candida species tested are susceptible to <1mg/ml A. sativum oil, and the majority are susceptible to fluconazole. Susceptibility decreases in biofilm cells, with increased resistance to fluconazole compared with A. sativum oil. The essential oil of A. sativum is thus active against clinical isolates of Candida species obtained from dentures, with effects on both biofilm and planktonic cells in vitro (AU)

Antecedentes. La colonización por parte de Candida albicans de las superficies de las prótesis dentales se asocia con el desarrollo de estomatitis. Se ha propuesto el uso de fluconazol, pero su desventaja es la resistencia microbiana. El aceite de Allium sativum ha mostrado su efectividad al controlar la formación de biopelícula de objetivos. Objetivos. Determinar la sensibilidad de cepas clínicas de especies de Candida, obtenidas de prótesis dentales parciales o totales rígidas de base acrílica, al aceite esencial de A. sativum y comparar su efecto en células planctónicas y en biopelícula. Métodos. Se incluyeron 48 cepas clínicas de la superficie acrílica de prótesis dentales totales o parciales, identificadas entre las siguientes especies: C. albicans, Candida glabrata, Candida tropicalis y Candida krusei. Se evaluó la sensibilidad de cada una al aceite esencial de A. sativum y al fluconazol mediante la metodología M27-A3 del CLSI, tanto sobre células planctónicas como en biopelícula, y mediante el método semicuantitativo de la reducción de XTT en el último caso. Resultados. Todas las cepas planctónicas de Candida fueron sensibles al aceite esencial de A.sativum, mientras que el 4,2% fue resistente al fluconazol. En cuanto a su sensibilidad en biopelícula, el 43,8% fue resistente a A. sativum y el 91,7% lo fue al fluconazol. Conclusiones. Todas las cepas en forma planctónica de las diferentes especies de Candida fueron sensibles a concentraciones inferiores a 1mg/ml del aceite esencial de A. sativum y en menor proporción a fluconazol. La sensibilidad disminuyó en las células en biopelícula, con mayor resistencia al fluconazol en comparación con el aceite esencial de A. sativum. Por tanto, el aceite esencial de A. sativum es activo frente a cepas clínicas de diferentes especies de Candida, obtenidas de dentaduras, con efectos en biopelícula y células planctónicas in vitro (AU)

Characterization of Oral Microbiota in Removable Dental Prosthesis Users: Influence of Arterial Hypertension.

INTRODUCTION: Studies have described the possible relation between oral infections and atherosclerotic events. OBJECTIVE: To characterize the oral microbiota of normotensive and hypertensive users of dental prostheses. METHODS: The sample consisted of 41 complete dental prosthesis users, divided into groups: 21 participants with systemic arterial hypertension and 20 normotensive participants. The data collection included the characteristics of the sociodemographic variables and the determination of the microbial load in the saliva. For the descriptive analyses, Statistical Package for the Social Sciences was used. The description of the proportional differences between the groups was based on the application of Mann-Whitney's statistical test. Statistical significance was set at 5% (p < 0.05). RESULTS: The analysis of the oral microbiota showed the vast growth of aerobic microorganisms in all samples from both groups. The microbial load of streptococci and staphylococci was significantly higher among hypertensive participants. Candida yeasts were detected in the saliva culture of most samples. The hypertensive participants rank in the category of very high colonization index/high risk of infection related to this microorganism. CONCLUSIONS: The mouth of dental prosthesis users, especially when hypertensive, can constitute an important reservoir of pathogens, indicating an established inflammatory or infectious condition or risk for developing this condition.

Occurrence and antimicrobial susceptibility of enteric rods and pseudomonads isolated from the dental prostheses biofilm.

OBJECTIVE:: To determine the occurrence and the in vitro antimicrobial susceptibility of enteric rods and pseudomonads from the denture biofilm of 52 subjects at the Center for Dental Specialties of Sobral/ Ceara, Brazil. MATERIAL AND METHODS:: Denture biofilm was collected and samples plated on MacConkey agar. The isolated bacterial colonies were identified using the BBL Crystal enteric/non-fermenter system. Antibiotic bacterial susceptibility was assessed by the disc diffusion method of amoxicillin, amoxicillin/clavulanic acid, doxycycline, tetracycline, tobramycin, imipenem, cefotaxime, and ciprofloxacin. The Minimum Inhibitory Concentration (MIC) of cefotaxime, tobramycin, doxycycline, imipenem, and ciprofloxacin was determined for 40 species by E-test. RESULTS:: 34 subjects (65.4%) harbored enteric rods in their prostheses. Klebsiella pneumoniae (26.5%), Escherichia coli (23.5%), and Enterobacter aerogenes (23.5%) were the most prevalent species. All organisms were susceptible to ciprofloxacin and most species were resistant to amoxicillin or amoxicillin/clavulanic acid, demonstrating variable sensitivity patterns to other antimicrobials. However, the MIC showed the emergence of strains with reduced sensitivity to ciprofloxacin (MIC90≥3 µg/ mL) and cefotaxime (MIC90≥2 µg/mL). CONCLUSION:: The findings show high prevalence of nosocomial diseases-related bacterial species and low susceptibility to antimicrobial drugs. Therefore, these results imply caution against the indiscriminate use of broad spectrum antibiotics in dental practice.

Occurrence and antimicrobial susceptibility of enteric rods and pseudomonads isolated from the dental prostheses biofilm

ABSTRACT Aspiration of oral bacteria leads to cardiac and respiratory infectious diseases and dentures can act as a reservoir for pathogenic microorganisms. Objective: To determine the occurrence and the in vitro antimicrobial susceptibility of enteric rods and pseudomonads from the denture biofilm of 52 subjects at the Center for Dental Specialties of Sobral/ Ceara, Brazil. Material and Methods: Denture biofilm was collected and samples plated on MacConkey agar. The isolated bacterial colonies were identified using the BBL Crystal enteric/non-fermenter system. Antibiotic bacterial susceptibility was assessed by the disc diffusion method of amoxicillin, amoxicillin/clavulanic acid, doxycycline, tetracycline, tobramycin, imipenem, cefotaxime, and ciprofloxacin. The Minimum Inhibitory Concentration (MIC) of cefotaxime, tobramycin, doxycycline, imipenem, and ciprofloxacin was determined for 40 species by E-test. Results: 34 subjects (65.4%) harbored enteric rods in their prostheses. Klebsiella pneumoniae (26.5%), Escherichia coli (23.5%), and Enterobacter aerogenes (23.5%) were the most prevalent species. All organisms were susceptible to ciprofloxacin and most species were resistant to amoxicillin or amoxicillin/clavulanic acid, demonstrating variable sensitivity patterns to other antimicrobials. However, the MIC showed the emergence of strains with reduced sensitivity to ciprofloxacin (MIC90≥3 μg/ mL) and cefotaxime (MIC90≥2 μg/mL). Conclusion: The findings show high prevalence of nosocomial diseases-related bacterial species and low susceptibility to antimicrobial drugs. Therefore, these results imply caution against the indiscriminate use of broad spectrum antibiotics in dental practice.

Candida/Candida biofilms. First description of dual-species Candida albicans/C. rugosa biofilm.

Denture liners have physical properties that favour plaque accumulation and colonization by Candida species, irritating oral tissues and causing denture stomatitis. To isolate and determine the incidence of oral Candida species in dental prostheses, oral swabs were collected from the dental prostheses of 66 patients. All the strains were screened for their ability to form biofilms; both monospecies and dual-species combinations were tested. Candida albicans (63 %) was the most frequently isolated microorganism; Candida tropicalis (14 %), Candida glabrata (13 %), Candida rugosa (5 %), Candida parapsilosis (3 %), and Candida krusei (2 %) were also detected. The XTT assay showed that C. albicans SC5314 possessed a biofilm-forming ability significantly higher (p < 0.001) than non-albicans Candida strains, after 6 h 37 °C. The total C. albicans CFU from a dual-species biofilm was less than the total CFU of a monospecies C. albicans biofilm. In contrast to the profuse hyphae verified in monospecies C. albicans biofilms, micrographies showed that the C. albicans/non-albicans Candida biofilms consisted of sparse yeast forms and profuse budding yeast cells that generated a network. These results suggested that C. albicans and the tested Candida species could co-exist in biofilms displaying apparent antagonism. The study provide the first description of C. albicans/C. rugosa mixed biofilm.