The effect of a chemomechanical protocol to eliminate microorganisms from pulpectomized primary teeth: three case reports

Introduction: Description of the bacterial community before and after chemomechanical preparation (CP) with the removal of a smear layer (SL) in pulpectomized primary teeth has been little reported. Objective: These case reports describe the presence of total microorganisms and Enterococcus faecalis in root canals of primary incisors before and after CP with SL removal. Case Reports: Microbiological samples were collected from the root canals of three children (3.66±0.58 years old) with necrosis (n=2) and irreversible pulpal inflammation (n=1) in maxillary primary incisors. After teeth isolation with a rubber dam and antisepsis of the operative field, the sample collections were performed with sterile absorbent paper cones before and after the CP, which included irrigation with 2.5% sodium hypochlorite followed by 6% citric acid to remove the SL. The collected samples were analysed immediately at the end of the clinical procedures. The plates were incubated anaerobically for 48 hours at 37°C. The results were expressed as colony forming units (CFU)/mL. Results: Two of the three teeth showed total microorganisms before the CP. One incisor had no microorganisms in the initial collection. No CFU was counted in the samples collected after CP. Moreover, E. faecalis was not observed any time, either before or after the CP. Conclusions: E. faecalis was not detected in any sample, yet two of the three root canals had microorganisms before CP. In cases where microorganisms were initially found, 100% elimination was observed after the applied protocol.

Introdução: A descrição da comunidade bacteriana antes e após o preparo químico-mecânico (PQM) com remoção da smear layer (SL) em dentes decíduos pulpectomizados tem sido pouco relatada. Objetivo: Esses relatos de casos descrevem a presença de microrganismos totais e Enterococcus faecalis em canais radiculares de incisivos decíduos antes e após PQM com remoção de SL. Relatos dos Casos: Amostras microbiológicas foram coletadas do canal radicular de três crianças (3,66 ± 0,58 anos) com necrose (n = 2) e inflamação pulpar irreversível (n= 1) em incisivos decíduos superiores. Após o isolamento dos dentes com dique de borracha e antissepsia do campo operatório, as coletas das amostras foram realizadas com cones de papel absorvente estéril antes e após o PQM, que incluiu irrigação com hipoclorito de sódio 2,5% seguido de ácido cítrico 6% para retirada do SL. As amostras coletadas foram analisadas imediatamente ao final dos procedimentos clínicos. As placas foram incubadas em anaerobiose durante 48 horas a 37°C. Os resultados foram expressos em unidades formadoras de colônias (UFC)/mL. Resultados: Dois dos três dentes apresentaram microrganismos totais antes do PQM. Um incisivo não apresentava microrganismos na coleta inicial. Nenhuma UFC foi contada nas amostras coletadas após o PQM. Além disso, o E. faecalis não foi observado nenhum momento, nem antes, nem depois do PQM. Conclusão: Não foi detectado E. faecalis em nenhuma amostra, porém dois dos três canais radiculares apresentavam microrganismos antes do PQM. Nos casos em que foram encontrados microrganismos inicialmente, observou-se 100% de eliminação após o protocolo aplicado.

Influence of thickness, color, and polishing process of ethylene-vinyl-acetate sheets on surface roughness and microorganism adhesion.

BACKGROUND/AIM: The surface roughness of dental materials can make cleaning difficult, thus facilitating retention of food debris and accumulation of microorganisms. The aim of this study was to assess whether thickness, color, and the polishing process influence the surface roughness of ethylene-vinyl-acetate (EVA) sheets and the amount of microorganisms that adhere to them. MATERIALS AND METHODS: A total of 180 samples of EVA (5 × 5 mm) were divided into 9 groups according to thickness (G1 = 2 mm; G2 = 3 mm; and G3 = 4 mm), color (G4 = black and G5 = white), and type of polishing (G6 = Scheu™; G7 = Scheu™ associated with hot-air burner; G8 = Erkodent™ and G9 = Erkodent™ associated with hot-air burner). Mean value of 3 roughness parameters was assessed: Ra, Rq, and Rz (one-way ANOVA test and Tukey's test, P < .05). Seven samples of each group (n = 63) were inoculated with saliva for 2 hours to promote microbial adhesion and count the number of colony-forming units (CFUs) (one-way ANOVA test, P < .05). Scanning electron microscopy (SEM) of microbial adhesion and the effects of the polishing process on the surface was assessed. RESULTS: Only the polishing parameter presented less roughness (G2, G7 and G9; P < .05) as also observed on SEM. SEM characterized microbial adhesion but the CFU count was not statistically significant, independent of the assessed parameters. CONCLUSION: The polishing systems, Scheu™ and Erkodent™ in association with a hot-air burner, were effective in decreasing the surface roughness without influencing the amount of adhered microorganisms.

Antibacterial Activity of Melaleuca alternifolia (tea tree essential oil) on Bacteria of the Dental Biofilm

Objective: To evaluate the antibacterial activity of tea tree EO on Streptococcus mutans (ATCC 25175), S. salivarius (ATCC 7073) and Lactobacillus rhaminosus (ATCC 9595). Material and Methods: The antibacterial activity of M. alternifolia EO was evaluated by the broth dilution method, by which minimum inhibitory and bactericidal concentrations (MIC and MBC) were determined. Serial dilutions range from 70243.90 µg/mL to 26.14 µg/mL. The MIC evaluation was performed in 96-well microplates, in which 100 µL of Brain Heart Infusion (BHI), 100 µL of the EO dilution and 5 µL of the inoculum (final concentration = 5x105 CFU/mL) were inserted. After 24 h of incubation, MIC was determined as the lowest concentration capable of inhibiting microbial growth, identified by the resazurin reaction (100 µg/mL). CBM was identified by the absence of subculture growths (50 µL) of dilutions equal to or greater than MIC. Tests were performed in triplicate and at three different times (n = 9). Pharmacological controls (0.05% and 0.12% Chlorhexidine), growth and sterility were used to validate the results. Results: The MIC of M. alternifolia compared to S. mutans, S. salivarius and L. rhaminosus was 1940.16 µg/mL, 3977.34 µg/mL and 3977.34 µg/mL, respectively. The MBC values were 70243.90 µg/mL, 3977.34 µg/mL and 34265.31 µg/mL, respectively. Conclusion: The essential oil of M. alternifolia presented antibacterial activity against the microorganisms evaluated when in high concentration.

Molecular Markers of Antimicrobial Resistance in Methicillin-Resistant Staphylococcus aureus SCCmec IV Presenting Different Genetic Backgrounds.

Methicillin-resistant Staphylococcus aureus (MRSA) carrying SCCmec type IV has emerged in hospitals worldwide. The aim of this study was to evaluate phenotypic and molecular characteristics of antimicrobial resistance in MRSA SCCmec IV isolates, presenting different genetic backgrounds, isolated from hospitals in Rio de Janeiro. The antimicrobial resistance of 128 S. aureus type IV isolates from 11 hospitals was characterized by the disk diffusion test and minimum inhibitory concentration (MIC) test. Mutations in parC gene, which encodes ciprofloxacin resistance, and genes associated with macrolide-lincosamide-streptogramin B (MLSb) resistance were also investigated. MRSA isolates belonging to USA400/ST1 (60 isolates), USA800/ST5 (40), USA1100/ST30 (13), and other 11 (15) lineages were mainly resistant to erythromycin (68%), ciprofloxacin (56%), and clindamycin (50%). The highest antimicrobial resistance rates were found among USA400 isolates (p < 0.05). The majority of them (90%) carried only the erm(C) gene and mainly presented two mutation types in the parC gene. The msr(A) gene was most frequently found among USA800 isolates (p < 0.05). Among MRSA type IV isolates from Rio de Janeiro hospitals, multiresistance, including mutations in parC gene, was associated to the USA400/ST1, while the msr(A) gene was associated with USA800/ST5 isolates, highlighting that these lineages could have more potential to persist in a hospital environment.

Does the Presence of Sucrose in Pediatric Antibiotics Influence the Enamel Mineral Loss and the Streptococcus mutans Counts in Dental Biofilm?

The role of antibiotics containing sucrose on the formation of dental caries is still controversial. This study aimed to investigate the effect of two antibiotics (amoxicillin and potassium clavulanate suspension), with and without sucrose, on human dental hardness and Streptococcus mutans counts in dental biofilm. Primary tooth fragments (n=72) were coated with nail varnish leaving a window of 2.25 mm diameter. Specimens were fixed in 24-well polystyrene plates, containing BHI medium. S. mutans (clinical strains) represented the inoculum to form biofilm on the fragments for 24 h. Twelve fragments were separated for the initial count of microorganisms (baseline). The other fragments were divided into 4 groups (n=12) of treatment: G1 (Clavulin(r)), G2 (Betamox(r)), G3 (chlorhexidine 0.12%), G4 (sucrose 10%). All specimens had their self-control area (covered area). The cross-sectional microhardness (CSMH) was evaluated for each specimen. All the treated groups had a loss of hardness compared to their self-controls (p<0.05). Both drugs inhibited the S. mutans growth and promoted no CSMH difference among them. Both antibiotics eliminated all formed biofilm and did not cause mineral loss from the enamel, regardless the presence of sucrose in its formulation.

O papel dos antibióticos contendo sacarose na formação de cárie dentária é ainda controverso. Este estudo teve como objetivo investigar o efeito de dois antibióticos (amoxicilina / clavulanato de potássio suspensão oral), com e sem sacarose, na dureza do esmalte dental humano e na contagem de Streptococcus mutans no biofilme dental. Fragmentos de dentes decíduos (n = 72) foram revestidos com verniz deixando uma janela de exposição de 2,25mm de diâmetro. Os espécimes foram fixados em placas de poliestireno de 24 poços, contendo meio de cultura BHI. S. mutans (estirpes clínicas) representaram o inoculo para formar biofilmes sobre os fragmentos por 24 h. Doze fragmentos foram separados para a contagem inicial de microrganismos (baseline). Os restantes dos fragmentos foram divididos em 4 grupos (n = 12) de tratamento: G1 (Clavulin(r)), G2 (Betamox(r)), G3 (clorexidina 0,12%), G4 (sacarose a 10%). Todas as amostras tiveram sua área de controle (área coberta). A microdureza transversal (CSMH) foi avaliada para cada espécime. Todos os grupos tratados tiveram uma perda de dureza quando comparados com os seus respectivos controles (p <0,05). Ambos os fármacos inibiram o crescimento de S. mutans e não promoveram diferença da CSMH entre eles. Ambos os antibióticos eliminaram todo o biofilme formado, não promovendo assim, perda mineral do esmalte, independente da presença de sacarose na sua formulação.

Oral bacteria adherence to suture threads: an in vitro study.

PURPOSE: This study investigated the adherence of oral microorganisms to different types of suture threads. METHODS: Pieces of thread were distributed on 24-well plates, according to the following groups: (G1) nylon, (G2) silk, (G3) polyglactin 910, (G4) polyglactin 910 with triclosan. Blank control (G5) consisted of one thread from each group. Adherence to thread tests was performed to observe adhesion of total microorganisms from saliva or two isolates of Prevotella intermedia (ATCC49046) and Fusobacterium nucleatum (ATCC51190). Brain-heart infusion (BHI) medium with or without bacterial inoculum (1.8 × 10(7) CFU/mL) was added to each well of microplates. The microplates were incubated in an anaerobic chamber at 37 °C, for 5 days for biofilm formation. RESULTS: There was no difference between the groups as regard to adhesion of F. nucleatum (p > 0.05). For P. intermedia, the threads in G1 and G4 showed a lower level of adhesion (p < 0.05), with no difference between them. Against total microorganisms, G1 presented a lower level of adherence (p < 0.05), followed by G4; and no difference was observed between G2 and G3. CONCLUSIONS: Total microorganisms and P. intermedia have different affinities to the tested suture threads, whereas F. nucleatum presented a similar adherence level. Among the threads, nylon (G1), followed by polyglactin 910 with triclosan (G4) presented the lowest microbial adherence level.

Heterogeneous resistance to vancomycin and teicoplanin among Staphylococcus spp. isolated from bacteremia

This study evaluated the BHIA screening method with 4 or 6 mug/mL of vancomycin to detect glycopeptides heteroresistant staphylococci strains isolated from bacteremia. A total of 213 staphylococci strains were isolated from 106 patients between October/2001 and November/2002 in a tertiary hospital in Rio de Janeiro city. Fifty-seven (53.8 percent) patients presented Staphylococcus aureus, while coagulase-negative staphylococci (CNS) were isolated from 49 (46.2 percent). Resistance rates for oxacillin of 26.3 percent and 81.6 percent were found for the staphylococci isolates, respectively. Thirteen CNS isolated from nine (8.5 percent) patients grew on agar screening with 4 mug/mL of vancomycin and showed heterogeneous profiles of resistance for vancomycin and teicoplanin by the population analysis profile method. Only 30.8 percent of them grew at the concentration 6 mug/mL. Bacterial infection and use of antimicrobial therapy were common among these patients. Alert about the emergence of oxacillin-resistant staphylococci presenting heteroresistance to glycopeptides is important in order to achieve judicious use of antimicrobials. Vancomycin agar screening test could help to confirm the presence of these isolates in hospitals.

Heterogeneous resistance to vancomycin in Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus warneri clinical strains: characterisation of glycopeptide susceptibility profiles and cell wall thickening.

The population analysis profile (PAP) method as well as analysis of autolytic activity and cellular ultrastructure by transmission electron microscopy (TEM) were used to characterise Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus warneri clinical strains with reduced susceptibility to glycopeptides. All strains showed heterogeneous profiles to vancomycin and teicoplanin by the PAP method. Subpopulations that grew in the presence of high concentrations of each drug were selected from the PAP as derivative strains. Their glycopeptide minimal inhibitory concentrations (MICs) were determined and subsequently all parental and derivative strains were grown in one-half of the MIC of vancomycin or teicoplanin. An increase in cell wall thickness of all derivative strains was seen by TEM, with statistically significant values (P<0.01) compared with their respective parental strains. In general, variable rates of autolysis among the strains were observed. Cell wall thickness is an important factor involved in glycopeptide resistance and, in association with PAP results, confirmed the Brazilian coagulase-negative staphylococci clinical isolates as being heteroresistant to glycopeptides. Detection of these heteroresistant organisms is important in order to achieve more judicious use of vancomycin and teicoplanin in hospitals.