Analysis of the microbial community diversity in various regions of the healthy oral cavity.

BACKGROUND: Microbiomics offers new methods for conducting epidemiological surveys of oral microbiota in large populations. Compared to curette sampling, swab sampling is more convenient and less technically sensitive, making it more suitable for such surveys. To verify the feasibility of using swabs for buccal mucosa sampling in large-scale studies, we collected samples from the buccal mucosa and tooth surfaces of healthy individuals using both swabs and curettes. Microbiomics was employed to analyze and compare microbial abundance and diversity between these two methods. METHODS: Four sites were assessed: the buccal mucosa on both sides and the buccal surfaces of the left and right mandibular first molars. Two sampling methods, swab and curette, were used to collect bacterial communities from healthy individuals. Specifically, buccal mucosa samples (n = 10) and tooth surface samples (n = 20) were analyzed using 16 S rDNA gene sequencing. Bacterial signals were detected through fluorescence in situ hybridization (FISH), targeting the bacterial 16 S rDNA gene. Metastats analysis and Wilcoxon test were used. RESULTS: A total of 383 OTUs were detected in the 30 samples, which belonged to 1 kingdom (bacteria), 11 phyla, 23 classes, 40 orders, 75 families, 143 genus, and 312 species. Among them, 223 OTUs were found on both the buccal mucosa and tooth surfaces. The statistics suggest that although there were no significant differences in colony composition, there were differences in the abundance and distribution of colonies on the dental and buccal mucosal surfaces. When detecting oral disease-causing pathogens such as Enterococcus faecalis and Porphyromonas gingivalis, the efficiency of detection is higher when using curette sampling. Compared to right tooth sampling with a curette, the swab sampling group had higher levels of Firmicutes, while Fusobacteria and Bacteroidetes were more prevalent in the curette tissues. CONCLUSIONS: In oral health individuals, there is no difference in the bacterial composition of the oral buccal mucosa and the dental surface, differing only in abundance. Thus, the buccal mucosa can act as a substitute for the teeth in epidemiological investigations exploring the bacterial composition of the oral cavity.

Elimination of E. faecalis with NaOCl versus chlorhexidine gluconate from primary molar root canal systems: an ex vivo model study.

OBJECTIVES: This ex vivo human study aimed to evaluate the efficacy of NaOCl and chlorhexidine gluconate (CHG) irrigations in eliminating Enterococcus faecalis from the RCS of primary molars. MATERIALS AND METHODS: Disinfected extracted primary molars were inoculated with E. faecalis for 24 h. Then, the RCS samples were then irrigated with either 2.5% NaOCl, 0.2% and 2% CHG, or sham saline. The samples were collected immediately after irrigation; and 24 h later, the bacterial viability and counts were measured using blood agar and qRT-PCR, respectively. Histological sections were used to measure E. faecalis penetration and viability in dentin tubules using fluorescence microscopy. RESULTS: The recovery of viable E. faecalis after the irrigation of the primary molars showed more significant bactericidal effects of NaOCl and 0.2% and 2% CHG than of saline. Immediately after the irrigation, the NaOCl group showed the greatest reduction in E. faecalis; and 24 h later, all the groups had lower viable E. faecalis than the saline control. The bacterial penetration was also lowest in the NaOCl group, although there was no difference in bacterial viability in the tubules between the groups. CONCLUSION: In primary teeth, NaOCl and CHG showed similar degrees of bacterial elimination efficacy in terms of E.faecalis. CLINICAL RELEVANCE: Within the limitations of this study, NaOCl and CHG have the similar ability to perform endodontic irrigation of primary ex vivo teeth regarding the elimination of E.faecalis, but NaOCl penetrates dentin tubules better.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study.

AIM: To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape. METHODOLOGY: After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%). RESULTS: All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05). CONCLUSION: The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

Efficacy of the GentleWave System in the removal of biofilm from the mesial roots of mandibular molars before and after minimal instrumentation: An ex vivo study.

AIM: To compare the efficacy of Enterococcus faecalis biofilm removal using the GentleWave System (GWS) (Sonendo Inc, CA) on non-instrumented versus minimally instrumented root canal systems. METHODOLOGY: Thirty-four mandibular molars were autoclaved and allocated to four groups: Negative control (n = 5); positive control (n = 5); Group 1: non-instrumentation + GWS (NI + GWS) (n = 12); and Group 2: minimal instrumentation + GWS (MI + GWS) (n = 12). Of 34 samples, 24 samples with Vertucci type 2 configuration within the mesial root of each sample were allocated to Groups 1 and 2 and then matched based on the working length and root canal configuration. After inoculation of samples with E. faecalis for 3 weeks, the GWS was used on Group 1 without any instrumentation and Group 2 after instrumentation of mesial canals until size 20/06v. CFU and SEM analysis were used. RESULTS: Log10 (CFU/mL) from the positive control, and Group 1 and 2 were 7.41 ± 0.53, 3.41 ± 1.54, and 3.21 ± 1.54, respectively. Both groups showed a statistically significant difference in the reduction of viable E. faecalis cells compared to the positive control (Group 1 [p = .0001] and Group 2 [p < .0001]), whilst showing no significant difference between the two tested groups (p < .05). CONCLUSION: The use of GWS on the non-instrumented root canal system could be an effective disinfection protocol in removing the biofilm without dentin debris formation.

Microbial load after selective and complete caries removal in permanent molars: a randomized clinical trial

Abstract The aim of this randomized clinical trial was to compare the remaining microbial load after treatments based on complete and selective caries removal and sealing. Patients with active carious lesions in a permanent molar were randomly allocated into 2 groups: a test group (selective caries removal-SCR; n=18) and a control group (complete caries removal - CCR; n=18). Dentin samples were collected following the excavation and three months after sealing. Streptococcus species, Streptococcus mutans, Lactobacillus species, and total viable microorganisms were cultured to count the viable cells and frequency of species isolation. CCR resulted in significant lower total viable microorganisms counts (p≤0.001), Streptococcus species (p≤0.001) and Lactobacillus species (p≤0.001) initially. However, after sealing, a decrease in total viable microorganisms, Streptococcus species, and Lactobacillus species in the SCR resulted in no difference between the groups after 3 months. In conclusion, selective caries removal is as effective as complete caries removal in reducing dentin bacterial load 3 months after sealing.

Resumo O objetivo deste ensaio clínico randomizado foi comparar os microrganismos remanescentes após tratamentos baseados em remoção total de tecido cariado e selamento e a remoção seletiva de tecido cariado e selamento. Pacientes com lesões de cárie ativas em molares permanentes foram divididos aleatoriamente em dois grupos: grupo teste (remoção seletiva de tecido cariado-SCR; n=18), e grupo de controle (remoção total de tecido cariado-CCR; n=18). Amostras de dentina foram obtidas após a remoção da tecido cariado e após 3 meses de selamento das cavidades. Streptococcus spp., Streptococcus mutans, Lactobacillus spp. e microrganismos viáveis totais foram cultivados para contagem de células e frequência de isolamento de espécies. CCR resultou em menores contagens totais de microorganismos viáveis (p≤0,001), Streptococcus spp. (p≤0,001) e Lactobacillus spp. (p≤0,001) inicialmente. Entretanto, após o selamento, uma redução significativa nas contagens totais de microrganismos viáveis, Streptococcus spp. e Lactobacillus spp. resultou em nenhuma diferença entre os grupos após 3 meses. Conclui-se que a remoção seletiva de cárie é tão seletiva quanto a remoção completa de cárie na redução da infecção dentinária após três meses com selamento da lesão.

Morphological Assessment and Cleaning Capacity of a Reciprocating System in Root Canals of Deciduous Teeth

Objective:To assess root canal morphological results and cleaning capacity in deciduous teeth instrumented with a reciprocating system.Material and Methods:15 deciduous molars and a total of 24 canals were selected for the study. Nine teeth(13 canals) were selected at random for microbiological analysis and 6 teeth (11 canals) were used for tomographic analysis of morphology. The roots used for the microbiological assessment were contaminated with standard strains of Enterococcus faecalis. All roots were instrumented using the WaveOne System with a Small (21:06) 21mm file and an X-Smart plus motor. Tomography was conducted with an I-CAT machine before and after instrumentation with the objective of analyzing the WaveOne System's shaping capacity. Statistics: Biostat 4.0 software was used to analyze results. The microbiological results (log10) and tomographic results (pixels) were analyzed using descriptive statistics and the Wilcoxon test.Results:There was a significant reduction in Enterococcus faecalis colony-forming units after instrumentation of the root canal systems of deciduous molars using the WaveOne system (p=0.0033) and significant enlargement of the root canal systems was observed after instrumentation (p=0.047), while morphology was maintained. Conclusion:The WaveOne System, using the Small file was effective for disinfection of the root canal systems of deciduous molars

The antimicrobial effect of iodine-potassium iodide after cleaning and shaping procedures in mesial root canals of mandibular molars

The aim of this study was to evaluate the antibacterial activity of 2% iodine potassium iodide (IKI) used as a final rinse after the cleaning and shaping procedures in mesial root canals of mandibular molars infected with Enterococcus faecalis. Seventy two mandibular first molars were used. The root canals were infected with Enterococcus faecalis for 30 days. After the infection procedures, the root canals were cleaned and shaped by using the ProTaper rotary system and manual files. The teeth were randomly assigned to four experimental groups (N=18). In group 1, the root canals were irrigated with sterile distilled water (control). In group 2, the root canals were irrigated with 1% Sodium hypochlorite (NaOCl) during instrumentation. In group 3, root canals were irrigated with 1% NaOCl during instrumentation and a five minute final irrigation using 2 % IKI. In group 4, the root canals were irrigated with 1% NaOCl during instrumentation and a 15 minutes final irrigation with 2 % IKI. Bacteria colony-forming units (CFU) from root canals were semi-quantified and the presence of negative cultures among the groups was compared using Fisher’s test (p < 0,05). The order of effectiveness was: 1% NaOCl plus 2% IKI for 15 minutes (95%), 1% NaOCl plus 2% IKI for 5 minutes (44%), 1% NaOCl (17%) and sterile distilled water (0%). Fisher’s exact test showed a significant difference among the groups (p<0.05). It was concluded that under in vitro conditions, IKI was able to eliminate the Enterococcus faecalis from infected dentin significantly in a 15-minute time frame after the cleaning and shaping procedures.

El objetivo del presente trabajo fue determinar el efecto in vitro del yoduro de potasio yodado al 2% posterior a la preparacion quimiomecanica en conductos radiculares infectados con Enterococcus faecalis. Para este estudio, se emplearon 72 primeras molares inferiores permanentes de humanos, los cuales fueron infectados con Enterococcus faecalis ATCC 29212. Los conductos fueron preparados mediante instrumentacion rotatoria y distribuidos de manera aleatoria en cuatro grupos de acuerdo al irrigante empleado: Grupo 1, agua destilada esteril; Grupo 2, NaOCl al 1%; Grupo 3: NaOCl al 1% IKI al 2% durante cinco minutos; y, Grupo 4: NaOCl al 1% mas IKI al 2% durante 15 minutos. Se tomaron muestras pre y postoperatorias de los conductos y se realizo la semicuantificacion microbiologica de las unidades formadoras de colonias de las bacterias. Fue comparada la presencia de cultivos negativos en los grupos mediante el test de Fisher utilizando un nivel de significancia de p < 0.05. El orden de efectividad para la desinfeccion de los conductos radiculares de mayor a menor fue: NaOCl al 1 % mas IKI al 2% durante 15 minutos (95%), NaOCl al 1% mas IKI al 2% durante 5 minutos (44%), NaOCl al 1% (17%) y agua destilada (0%). Se concluye, que bajo las condiciones in vitro de este estudio, el yoduro de potasio yodado empleado despues de la instrumentacion fue capaz de eliminar significativamente a la bacteria Enterococcus faecalis en un tiempo de 15 minutos.

Evaluation of food retention in occlusal surfaces of first primary molars / Evaluación de la retención de alimentos en las superficies oclusales de los primeros molares temporales

Some food characteristics, like stickiness and consistency, can modify the time for food removal from the mouth as well as favors the activity of cariogenic bacteria, increasing dental caries risk. This study aimed to observe food retention in contact with a cariogenic substrate in 24-30 months old children. Therefore, 27 children (54 teeth) were evaluated. They intake a chocolate cookie and the food retention area was documented by digital photography in two experimental times (to: 0 and t1: 30 minutes) and it was calculated using Image Tool 3.0 software. The food retention surface index (mm2) was statistically reduced (Wilcoxon’s test, p=0.001) after 30 minutes for both maxillary (to: 0.37 +/- 0.04 and t1:0.042 +/- 0.015) and mandibular (to: 0.30 +/- 0.03 and t1: 0.078 +/- 0.019) molars. No differences were observed between the groups in food retention surface index at the initial time. At the final time, the mandibular molars show a higher retention area than the maxillary ones (Mann-Whitney’s test, p=0.04). The prevalence of food retention at the mandibular molars is higher than the maxillary molars (Chi Square’s test, p=0.03). In conclusion, first primary mandibular molars retain more food than the maxillary molars, being in agreement with clinical results of dental caries’ prevalence.

Algunas características de los alimentos, como la viscosidad y consistencia, puede modificar el tiempo para el retiro de alimentos de la boca, así como favorecer la actividad de las bacterias cariogénicas, y el aumento de riesgo de caries dental. Este estudio tuvo como objetivos verificar la retención de alimentos en contacto con un sustrato cariogénico en niños de 24-30 meses de edad. 27 niños (54 dientes) fueron evaluados. Se realizo la ingesta de una galleta de chocolate, y la zona de retención del alimento fue documentada por la fotografía digital en dos tiempos de experimentación (to: 0 y t1: 30 minutos) y se calculó utilizando el software Image Tool 3.0. El índice de superficie (mm2) de retención de alimentos fue estadísticamente reducido (test de Wilcoxon, p = 0,001) después de 30 minutos para molares maxilares (to: 0,37 +/- 0,04 y t1: 0,042 +/- 0,015) y mandibulares (to:0,30 +/- 0,03 y t1: 0,078 +/- 0,019). No se observaron diferencias en El índice de superficie de retención de alimentos entre los grupos en el tiempo inicial. En el momento final, los molares inferiores muestran una zona de retención superiores a los maxilares (prueba de Mann-Whitney, p = 0,04). La prevalencia de la retención de alimentos en los molares inferiores fue más alta que los molares superiores (Chi cuadrado, p = 0,03). En conclusión, los primeros molares mandibulares primarios retienen más alimentos que los molares superiores, siendo concordante con los resultados clínicos de la prevalencia de caries.

Estreptococos cariogénicos predominantes, niveles de infección e incidencia de caries en un grupo de escolares: estudio exploratorio / Predominant cariogenic Streptococcus, infection level and caries incidence in a group of schoolchildren: en exploratory study

Objetivo: Estudiar la distribución de estreptococos cariogénicos, niveles de infección y su asociación con la incidencia de caries. Metodología: Sesenta escolares (8 y 10 años), seguidos durante 18 meses. Se registró caries, niveles bacterianos de estreptococos en muestras de placa; por medio de análisis bioquímico se hizo la tipificación bacteriana, se calculó la incidencia de caries en el molar muestreado. Resultados: El 80 por ciento de los estreptococos correspondieron al grupo mutans (40 por ciento S. sobrinus, 32 por ciento S. mutans, 5 por ciento S. rattus y 3 por ciento S. cricetus). El 20 por ciento restante correspondió a otros estreptococos (S. salivarius, S. mitis y S. sanguis). El 55 por ciento de los niños presentó conteos 105 ufc/mL en placa y el 30 por ciento desarrolló caries en el molar estudiado. Un modelo de regresión logística múltiple de pasos sucesivos mostró asociación entre la bacteria predominante y los niveles de infección (P < 0.01). No se demostró asociación entre bacteria predominante e incidencia de caries (P > 0.05). Sin embargo con el mismo modelo ponderado según los niveles de infección, mostró una asociación significativa (P < 0.0018). Conclusión: La asociación de cepas de estreptococos con la incidencia de caries en niños es dependiente del nivel de infección

Correlación entre el índice de placa de superficies libres e índice de placa oclusal en niñas / Correlation between free surfaces plaque index and occlusal plaque index in girls

El objetivo de este trabajo fue analizar la asociación y correlación entre el índice de placa oclusal e índice de placa de Loe y Silness en un grupo de niñas entre 6 y 12 años de edad que asisten a una Escuela Hogar de la Ciudad de Buenos Aires. Fue registrado el índice de placa de Loe y Silness (IP), en 309 molares y premolares, en las superficies vestibular, mesial, distal y lingual o palatino. En las mismas piezas fue registrado el índice de placa oclusal (IPO) según Macucho M. E. y colaboradores. (J. Dent. Res. 78(5): Abstr. 77, 1999). Se realizó la media aritmética y error estándar, X2, coeficiente de correlación de Spearman y distribución de frecuencia de ambos índices. Los resultados mostraron un índice de placa oclusal e índice de superficies libres de Loe de X 1,65+-0,10 y 1,42+-0,08 respectivamente. Se observó asociación y correlación significativa (p<0,001) entre ambos índices: X2: 10,69; rho 0,49. La distribución de frecuencia de ambos índices en molares y premolares muestran algunas concordancias entre los grados de severidad de placa. Los resultados obtenidos muestran que si bien hay asociaciones y correlaciones, el registro simultáneo permitiría la obtención de índices de placa que incluyan todas las superficies dentarias (AU)

Immunohistochemical and biochemical analysis of laminin in neonatal rat first molars / Análise imunohistoquimica e bioquímica da laminina de primeiros molares neonatais de rato

Rabbit polyclonal antibody against mouse EHS laminin was used to investigate the distribution and composition of laminin in the rat first molar tooth germ. Immunohistochemical analysis showed that laminin is expressed in the inner and outer epithelia of the enamel organ and in small blood vessels in the dental papilla and strellate reticulum. Immunoblots revealed that tooth germ laminin differs from EHS laminin. Tooth germ laminin contain ß chains, while the (alfa)1 chain is substituted by a 300-kDa chain. Two-dimensional electrophoresis analysis of tooth germ extract showed that ß chains appeared as four spots with approximate pI values of 6.6, 7.5, 7.8 and 8.5. These results indicate that more than one type of laminin isoform is present in the first molar tooth germ. Additionally, we have shown that despite the early degradation of tooth germ basement membrane, the laminin molecule is still intact at the time of birth

Eficacia antimicrobiana de las soluciones de hidróxido de calcio y clorhexidina al 0.1 por ciento sobre la flora bacteriana de molares temporales necrosados / Antomicrobial efficacy of calcium hydroxide and chlorhexidine solutions of 0.1 percent to the bacterial flora of necrosed temporal tooth

En el presente trabajo se realizó un estudio comparativo de la eficacia antimicrobiana in vitro de las soluciones de hidróxido de calcio y clorhexidina al 0.1 por ciento sobre la flora bacteriana aislada de molares temporales necrosados de niños entre cinco y ocho años. Las muestras fueron sembradas en placas petri con agar sangre heminamenadiona. A una de las placas se le colocó en la superficie un disco de papel filtro embebido en clorhexidina al 0.1 por ciento, a otra placa hidróxido de calcio y la tercera fue usada como control. En estas condiciones fueron cultivadas en anaerobiosis por siete días. Se concluyó que el efecto antibacteriano in vitro de la clorhexidina es significativamente mayor que el del hidróxido de calcio sobre la flora bacteriana aislada de molares temporales necrosados