Propylene Glycol Potentiates the Inhibitory Action of CTZ Paste on Antibiotic-Resistant Enterococcus faecalis Isolated from the Root Canal: An In Vitro Study.

This study aimed to evaluate if the change of vehicle for CTZ (Chloramphenicol, Tetracycline, zinc oxide, and Eugenol) paste improves the inhibition of Enterococcus faecalis in vitro. The vehicles evaluated alone and mixed with CTZ were Eugenol, propylene glycol (PG), super-oxidized solution (SOS), grapefruit-seed extract (GSE), and 0.9% saline solution as a negative control. A clinical isolate of E. faecalis was morphologically and biochemically characterized, and its antimicrobial susceptibility was tested using 20 antimicrobial agents. Once characterized, the clinical isolate was cultivated to perform the Kirby-Bauer disc diffusion method with paper discs embedded with the different vehicles mixed or used alone, and incubated at 37 °C for 24 h. Data were analyzed using one-way ANOVA, and the means were compared using Tukey test with a significance level of p < 0.05. For vehicles used alone, GSE presented the greatest inhibition showing a statistically significant difference with the rest of the vehicles. When vehicles were mixed with the CTZ paste, PG showed a greater inhibition with a statistically significant difference from the rest of the vehicles. In conclusion, the vehicle used to mix the CTZ paste plays an important role in the inhibition of E. faecalis in vitro; therefore, we consider that this can be an important factor to achieve success in the use of this technique.

Prueba de Push-Out para Evaluar la Fuerza de Adhesión entre dos Tipos de Postes Estéticos

Posterior a un tratamiento endodóntico, muchas veces el remanente es insuficiente para la retención de un material de restauración, por este motivo es necesario la colocación de un sistema de poste-muñón para otorgar retención a la restauración final. Con la aparición de diversos materiales para las restauraciones estéticas, se utilizan actualmente resinas reforzadas con fibra de vidrio como sistemas de postes y muñones para la restauración de dientes tratados endodónticamente. El objetivo del presente trabajo fue comparar la fuerza de adhesión en la prueba push-out de dos diferentes tipos de postes de fibra de vidrio; 3M RelyX y Rebilda Post GT (VOCO) adheridos con cementos duales correspondientes a la marca de los postes; RelyX U-200® Automix (3M ESPE) y Rebilda DC (VOCO). Se llevó a cabo un análisis de ANOVA de dos vías para comparar la fuerza adhesiva con la prueba push-out entre ambos grupos de estudio. Pese a que se observó que los postes Rebilda presentaron una media de fuerza de adhesión ligeramente mayor en comparación con los postes 3M (sin diferencia estadística significativa P>0,05) los últimos son clínicamente más fáciles de colocar, lo cual pudiera ser un factor decisivo para el clínico en el momento de la elección de un poste y su sistema de adhesión.

After an endodontic treatment, many times the remnant is insufficient for the retention of a restorative material, for this reason it is necessary to place a post-stump system to provide retention to the final restoration. With the advent of various materials for esthetic restorations, fiberglass-reinforced resins are now used as post and core systems for the restoration of endodontically treated teeth. The objective of the present work was to compare the bond strength in the push-out test of 2 different types of fiberglass posts; 3M RelyX and Rebilda Post GT (VOCO) bonded with dual cements corresponding to the post brand; RelyX U-200® Automix (3M ESPE) and Rebilda DC (VOCO). A 2-way ANOVA analysis was performed to compare push-out strength between both study groups. Although it was observed that the Rebilda posts presented a slightly higher mean bond strength compared to the 3M posts (with no significant statistical difference P>0.05), the latter are clinically easier to place, which could be a decisive factor for the clinician at the time of choosing a post and its adhesion system.

In-Vitro silanization of dental enamel to prevent demineralization / Silanización in vitro sobre esmalte dental para prevenir desmineralización

Abstract Caries is a multifactorial disease that can negatively affect dental tissues through the demineralization process, which produces acids deriving from the metabolism of carbohydrates. Some strategies to prevent this process have been proposed, such as topical fluoride application, resin-based restorations, pit and fissures sealers, infiltrated resins, vaccines, mouthwashes, and several brushing techniques. Objective. To evaluate in vitro enamel hydrophobic modification as a method of prevention against demineralization. A descriptive and comparative study was carried out. Thirty premolars extracted for orthodontic reasons were obtained, encapsulated in epoxy resin, sectioned, and sanded to obtain specimens 3mm in thickness. The samples were pretreated with NaOCl and EDTA, incubated with 1 and 4% octadeyltrichlorosilane (OTS) or with 3 and 6% octadecyltriethoxysilane (TEOS) for 5min and for 8h. Subsequently, the samples were immersed in citric acid for 2 months. The samples were analyzed by their contact angle, infrared spectroscopy, scanning electron microscopy, atomic and confocal force, before and after treatment in citric acid. The samples coated with 1 and 4% OTS for 5min and 8h kept the silanizing agent on their surface after 2 months in citric acid. The treatment with TEOS was only effective at 6% with a reaction time of 5min. The modification with 1 and 4% OTS protects the surface of the tooth enamel from demineralization in acidic medium. The results indicate that treatment with 4% OTS is effective from 5min, which makes it appropriate in clinical practice.

Resumen Introducción. Caries es una enfermedad multifactorial que destruye en tejido dental por la desmineralización de ácidos generados en el metabolismo de carbohidratos. Algunos métodos preventivos, como fluoruro, resinas, selladores de fosetas y fisuras, resinas infiltradas, vacunas, enjuagues bucales, y un sinfín de técnicas de cepillado, han sido empleadas. Objetivo. Evaluar in vitro la modificación hidrofoba del esmalte como método preventivo en contra de la desmineralización. Materiales y Métodos. Un estudio decriptivo y comparativo fue empleado. Se obtuvieron treinta premolares sanos extraidos por razones ortodónticas y encapsulados en resina epóxica, seccionados y pulidos hasta obtener especímenes de 3mm de grosor. Las muestras fueron pretratadas con NaOCl y EDTA, incubadas en octadeciltriclosorilano (OTS) al 1 y 4% y octadeciltrietoxisilano (TEOS) 3 y 6% por 5min y 8h. Después, las muestras fueron sumergidas en ácido cítrico por 2 meses. Las muestras fueron analizadas con ángulo de contacto, espectroscopía infrarroja, microscopía electrónica de barrido, atómica y confocal, antes y después de tratamiento con ácido cítrico. Resultados. Las muestras cubiertas con OTS 1 y 4% por 5min y 8h mantuvieron el agente silanizante sobre la superficie después de 2 meses en ácido cítrico. El tratamiento con TEOS fue efectivo al 6% y con un tiempo de reacción de 5min. Conclusiones. La modificación con 1 y 4% de OTS proteje la superficie del esmalte dental contra la desmineralización en un medio ácido. Estos resultados indican que el tratamiento con OTS 4% es efectivo desde 5min de aplicación, lo cual es apropiado en la práctica clínica.

Effect of sodium hypochlorite in ground fluorotic enamel: Shear bond strength and surface analysis / Efecto del hipoclorito de sodio en esmalte fluorótico tallado: resistencia adhesiva al cizallamiento y análisis de la superficie

ABSTRACT: Evaluate the effect on the shear bond strength (SBS) of 5% NaOCl applied after acid etching on ground anterior teeth with fluorosis and analyze the surface with scanning electron microscopy (SEM), also compare fluorotic and healthy ground enamel by atomic force microscopy (AFM) and Vickers microhardness (VM). For the SBS test 30 anterior teeth with moderate and severe fluorosis according Dean index were selected by an examiner previously calibrated with an expert in fluorosis by using the intraclass correlation coefficient (ICC). With the help of a calibrated high speed diamond bur for veneer preparation and a parallel chamfer high speed diamond bur he vestibular face was prepared with a uniform reduction of .3 mm under water cooling. In one half of the vestibular face of the teeth the conventional adhesive procedure was carried out while in the other half was added an additional step with 5% NaOCl applied for 1 minute and washing after acid etchant. A resin post was adhered in each half and load was applied until fracture. The failure mode was evaluated and a SEM analysis was made. Posteriorly 10 samples of fluorotic and healthy ground enamel were used to measure the nanostructural characteristics by AFM (roughness average and absolute depth profile) and the VM in three operative steps (after ground, after etchant and after deproteinization). The Shapiro-Wilks and Brown-Forsythe methods were used to test the distribution of variables. The Paired Student's t-test was used to compare the differences between mean bond strength (MPa) in the two groups for SBS test. Chi- square analyzes were performed to compare the failure modes between groups. One- way ANOVA analysis and Tukey-Kramer post hoc test were used to compare groups for roughness average, absolute depth profile and Vickers microhardness. A greater SBS (32.17±4.20 MPa) and a surface more homogeneous and less contaminated were observed in the deproteinization subgruoup compared to the conventional subgroup (27.74±4.88 MPa). AFM parameters were greater in fluorosis subgroup than in healthy enamel subgroup. VM was lower in the fluorotic enamel in each operative step in comparation with healthy enamel. The use of 5% NaOCl as a deproteinizing agent after acid etchant in ground fluorotic enamel results in better adhesion, which may imply greater success in adhesive treatments. The ground surface of fluorotic enamel shows higher values of roughness and depth and lower values of VM which proves that there is a more irregular and less hard surface.

RESUMEN: Evaluar el efecto en la resistencia adhesiva al cizallamiento (SBS) de la aplicación de 5% de NAOCl después del grabado ácido en dientes anteriores fluoróticos tallados y analizar la superficie con microscopía electrónica de barrido (SEM), también comparar esmalte tallado fluorótico y sano por microscopía de fuerza atómica (AFM) y microdureza Vickers (VM). Para la prueba SBS 30 dientes anteriores con fluorosis moderada y severa de acuerdo al índice de Dean fueron seleccionados por un examinador previamente calibrado por un experto en fluorosis usando el coeficiente de correlación intraclase (ICC). La cara vestibular se preparó .3mm con la ayuda de una fresa calibrada para la preparación de carillas y una paralela con punta en chamfer de diamante a alta velocidad e irrigación. En una mitad de la superficie vestibular de los dientes se llevó a cabo el procedimiento adhesivo tradicional, mientras que en la otra mitad se incluyó un paso adicional con la aplicación de NaOCl al 5% por un minute y lavado posterior al grabado ácido. Un poste de resina fué adherido en cada mitad y se aplicó carga hasta la fractura. Se evaluó el modo de fallo y se realizó un análisis con SEM. Posteriormente se utilizaron 10 muestras de esmalte tallado fluorótico y sano para medir las características nano estructurales por medio de AFM (rugosisdad promedio y perfil de profundidad absoluta) y la VM en tres diferentes pasos operativos (posterior al tallado, posterior al grabado ácido y posterior a la desproteinización). Se utilizaron los métodos de Shapiro Wilks y Brown-Forsythe para conocer la distribución de las variables. Una T de student pareada se utilizó para comparar la diferencia entre los promedios de la fuerza de unión (MPa) entre grupos para la prueba SBS. Se llevaron a cabo análisis de chi cuadrada para comparer los modos de fallo entre los grupos. Análisis de ANOVA de una vía y Tukey-Kramer post hoc fueron utilizados para comparar los grupos para las variables rugosidad promedio, perfil de profundidad absoluta y microdureza Vickers. Se observó una mayor SBS (32,17±4,20 MPa) y una superficie más homogénea y menos contaminada en el subgrupo con desproteinización en comparación con el subgrupo convencional (27,74±4,88 MPa). Los parámetros de AFM fueron mayores en el subgrupo de fluorosis que en el subgrupo de esmalte sano. La VM fue más baja en el esmalte fluorótico en cada paso operativo en comparación con el esmalte sano. El uso de NaOCl al 5% como agente desproteinizante después del grabado ácido en el esmalte fluorótico tallado da como resultado una mejor adhesión, lo que puede implicar un mayor éxito en los tratamientos adhesivos. La superficie tallada del esmalte fluorótico muestra valores más altos de rugosidad y profundidad y valores más bajos de VM lo que prueba que existe una superficie más irregular y menos dura.

Influence of Heated Hydrofluoric Acid Surface Treatment on Surface Roughness and Bond Strength to Feldspathic Ceramics and Lithium-Disilicate Glass-Ceramics.

PURPOSE: To evaluate the effect of heated and room-temperature hydrofluoric (HF) acid on surface roughness parameters (Ra and Rq) and microtensile bond strength (µTBS) on feldspathic ceramic and lithium-disilicate glass-ceramics. MATERIALS AND METHODS: Disk-shaped samples made from both ceramics were divided into groups according to surface treatment: feldspathic ceramic polished surface (FP), feldspathic ceramic + 60 s of 9% HF acid etching at room temperature (FC), feldspathic ceramic + 60 s of 9% HF acid etching heated to 70°C (F70), lithium-disilicate polished surface only (LP), lithium disilicate + 20 s of 9% HF acid etching at room temperature (LC), and lithium disilicate + 20 s of 9% HF acid etching heated to 70°C (L70). To evaluate Ra and Rq, non-overlapping readings were taken on the surface of each sample with a contact stylus profilometer. To measure microtensile bond strength (µTBS), samples of groups FC, F70, LC and L70 received their corresponding surface treatment, were silanized and then bonded using a dual-cure composite cement to resin composite disks. After 24 h, samples were sectioned to obtain specimens for µTBS. Representative samples from each group were examined using scanning electron microscopy (SEM) to analyze the morphology of the etched surface. The data were analyzed for statistical significance using Welch's ANOVA with the Games-Howell multiple-comparison post-hoc test. RESULTS: For both surface roughness parameters and HF acid etching at room temperature (FC and LC) showed a significant increase (p < 0.001) in surface roughness when compared to polished surfaces (FP and LP). Furthermore, the use of heated HF acid etching significantly increased (p < 0.001) the surface roughness of the ceramic when compared to their counterpart sample of HF acid etching at room temperature. Group L70 obtained the highest µTBS of all groups (29.11 ± 8.26 MPa) and was significantly higher (p < 0.001) than that of the other experimental groups. There were no statistical differences (p > 0.05) between groups FC (19.94 ± 4.14), F70 (18.24 ± 5.29), and LC (17.87 ± 6.96). CONCLUSION: The use of 9% HF acid etching heated to 70°C resulted in significantly higher surface roughness and improved bond strength onto lithium-disilicate glass-ceramic compared to surface HF acid etching at room temperature.

Análisis Elemental de las Propiedades Morfológicas, Físicas y Químicas de Dos Instrumentos Rotatorios Protaper Universal

RESUMEN: Los instrumentos rotatorios utilizados en el tratamiento de conductos dentales necesitan cumplir con ciertas características físicas que le confieran un uso correcto, adecuado y seguro para su uso clínico. En el mercado comercial existen una serie de instrumentos importados que dejan en duda la autenticidad de estos debido a sus bajos costos. En este estudio evaluamos física, química y morfológicamente dos kits de instrumentos rotatorios Protaper universal (Dentsply) mediante análisis de MEB, EDX, microdureza y EDS. Uno de los kits (grupo 1) se adquirió directamente de la casa comercial y otro kit importado que a simple vista no parecía cumplir con los estándares de calidad de un correcto empaquetado (grupo 2). En el análisis de MEB se observaron características morfológicas muy diferentes entre ambos kits, el grupo 2 presentó diversas irregularidades en la superficie de las limas, sin embargo, en el EDS no se encontró diferencia alguna. En cuanto al análisis de microdureza se observó una estadística estadísticamente significativa y en el EDS se observaron mayores picos de intensidad en cuanto a la aleación de Ni-Ti en el grupo 2. Estos resultados sugieren que existen instrumentos rotatorios importados que a pesar de su bajo costo pueden presentar ciertas características muy similares a los kits auténticos, sin embargo, física y químicamente pueden resultar en un riesgo para su uso clínico debido a la diferencia entre estos.

ABSTRACT: Rotatory files are instruments used in the treatment of dental canals roots. These instruments need to comply with certain physical characteristics for a correct, adequate and safe use for clinical use. In the commercial market there are a series of imported instruments that cast doubt on their authenticity due to their low costs. In this study we physically, chemically and morphologically evaluated two Protaper universal rotary instrument kits (Dentsply) using SEM, EDX, microhardness and EDS analysis. One of the kits (group 1) was purchased directly from the commercial house and another imported kit that a simple view did not seem to meet the quality standards of a correct packaging (group 2). In the SEM analysis, very different morphological characteristics were observed between both kits, group 2 presented various irregularities on the surface of the files, however, no difference was found in the EDS. Regarding the microhardness analysis, a statistically significant statistic was observed and in the EDS, higher intensity peaks were observed in terms of the Ni-Ti alloy in group 2. These results suggest that there are imported rotary instruments that despite their low cost can present characteristics very similar to authentic kits, however, physically and chemically they can result in a risk for their clinical use due to the difference between them.

Saliva: What Dental Practitioners Should Know about the Role of This Biofluid in the Transmission and Diagnostic of SARS-CoV-2.

A novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has become a global ongoing pandemic. This pandemic represents a great work risk for all health professionals, it includes dental professionals who are in constant contact with saliva, which represents one of the main routes of transmission of the disease. This is due to the fact that a wide variety of oral tissues and cells are susceptible to infection by SARS-CoV-2 and that they express the ACE2 receptor, which is the main route of entry of the virus into cells, as well as the proteins TMPRSS and furin that contributes to the binding of the virus to the host cells. According to recent studies, some of the oral cells most susceptible to infection by SARS-CoV-2 are the epithelial cells of the salivary glands. This explains the presence of the virus in the saliva of infected patients and provides scientific evidence that supports the use of saliva as a biofluid that offers the opportunity to develop new detection and diagnostic techniques. This is because saliva is much easier to collect compared to nasopharyngeal swab. However, the presence of the virus in saliva, also represents a great source of transmission, since the main form of infection is through microscopic drops that are generated when infected people cough or sneeze. Likewise, health professionals, such as dentists are exposed to contagion through saliva. The objective of this review article is to provide a perspective on the main cells and tissues that can be affected by the virus, the risk of contagion that the presence of the virus in saliva represents for dentists; and the new techniques developed from saliva samples for the diagnosis and surveillance of SARS-CoV-2 infection. This review is expected to contribute to the knowledge of oral health professionals about the risk of saliva in the spread of SARS-CoV-2, but also its advantages as a diagnostic tool for pandemic control. In conclusion, the authors can mention that information that provides more scientific evidence of the mechanisms of infection of the coronavirus in oral cells and tissues is being published continually. This also explains the presence of the virus in the saliva of infected people and the risk of contagion that this means. It also provides scientific evidence of the use of saliva as a biofluid for the detection, diagnosis, monitoring, and control of the spread of the virus.

Characterization of Enamel After the Use of Oral Hygiene Auxiliaries with Whiteners / Caracterización del esmalte después del uso de auxiliares de higiene bucal con blanqueadores

ABSTRACT The purpose of this study was to evaluate the effect of the use of the combined auxiliaries of oral hygiene with whitening agents on the micro-hardness and micro-morphology of dental enamel. Materials and Methods. 40 human incisors were used and sectioned to obtain 4x4mm samples and divided into four study groups. Group 1: Electric brushing with Toothpaste (BTP); Group 2: Electric brushing with Toothpaste+mouthwash (BTP+MW); Group 3: Electric brushing with Toothpaste+whitening pen (BTP+WP); Group 4: Electric brushing with Toothpaste+mouth wash+whitening pen (BTP+MW+WP). Samples were submitted toVickers micro-hardness test and visualized using scanning electron microscopy (SEM). Results. All groups, with the exception of group 1, showed a decrease in micro- hardness values after applying the treatments (p<0.05). Likewise, when comparing the values after the treatments between the groups, significant statistical differences were found in all of comparisons except for those of groups 2 and 4. SEM images showed changes in the morphology in all the study groups with the exception of group 1. Conclusion. Significant changes such as decrease in micro-hardness as well as in the topography of the enamel surface such as elevations, craters, porosities and etching patterns were founded after the use of the combination of auxiliaries of oral hygiene with whitening agents.

RESUMEN El propósito de este estudio fue evaluar el efecto del uso de los auxiliares de higiene oral combinados con agentes blanqueadores sobre la microdureza y la micro-morfología del esmalte dental. Materiales y métodos. Se utilizaron 40 incisivos humanos y se seccionaron para obtener muestras de 4x4 mm los cuales se dividieron en cuatro grupos de estudio. Grupo 1: cepillado eléctrico con pasta de dientes (BTP); Grupo 2: cepillado eléctrico con pasta dental+enjuague bucal (BTP+MW); Grupo 3: cepillado eléctrico con pasta dental+pluma blanqueadora (BTP+WP); Grupo 4: cepillado eléctrico con pasta dental+enjuague bucal+pluma blanqueadora (BTP+MW+WP). Las muestras fueron analizadas por medio de microdurezaVickers y microscopía electronica de barrido (SEM). Resultados. Todos los grupos, con la excepción del grupo 1, mostraron una disminución en los valores de microdureza después de aplicar los tratamientos (p<0.05). Del mismo modo, al comparar los valores después de los tratamientos entre los grupos, se encontraron diferencias estadísticamente significativas en todas las comparaciones, excepto en las de los grupos 2 y 4. Las imágenes de SEM nos muestran cambios en la morfología en todos los grupos de estudio con la excepción del grupo 1 Conclusión. Cambios significativos como la disminución de la microdureza y los cambios en la topografía de la superficie del esmalte, como elevaciones, cráteres, porosidades y patrones de grabado, se encontraron después del uso de la combinación de auxiliares de la higiene oral con agentes blanqueadores.

Diagnostic accuracy of three placement sites for the cold test in subjects amongst different age groups.

BACKGROUND: The cold test is a specific test of pulp sensitivity and is part of the endodontic diagnosis. The aim of this study was to identify the diagnostic accuracy including sensitivity, specificity, accuracy, positive predictive value and negative predictive value in three sites for the cold test in teeth with a need for endodontic treatment within different age groups from both genders. METHODS: A cross-sectional study was performed, evaluating 425 subjects. Two hundred and fifty-eight subjects from both genders from the ages of 17-27, 28-39, 40-50, and 51-65 years-old participated in the study. The cold test studied was 1, 1, 1, 2-tetrafluoroethane, and the gold standard was established through direct pulp inspection. The sites evaluated in the study were: The sites evaluated in the study were: a) the middle third of the buccal surface; b) the cervical third of the buccal surface, and c) the middle third of the lingual surface. RESULTS: The highest diagnosted accuracy was observed on the middle third buccal surface with an accuracy of = 0.97, a sensitivity of = 1.00, a specificity of 0.95, a predictive value of = 0.95 and a negative predictive value of = 1.00. This was in the female group aged from 40 to 50 years old. CONCLUSION: The tables of this study can be used as an auxiliary for pulp sensitivity tests.

Identification of the Most Appropriate Site for the Cold Test in Molar Teeth / Identificación del sitio más apropiado para la prueba de frío en dientes molares

Abstract A test frequently used to complement endodontic diagnoses is the cold test; however, in the last 20 years, authors have reported incorrect results within pulp sensitivity tests. Specifically, a high frequency of false results in posterior teeth, were found. The aim of this study was to identify the most appropriate site for the cold test in molar teeth with a need for endodontic treatment, calculating predictive values, accuracy and reproducibility. A cross-sectional study was performed, evaluating 390 subjects. A total of 152 subjects of both genders from the ages of 15-65 years old participated. The ideal standard was established by direct pulp inspection, and the cold test agent used was 1,1,1,2-tetrafluoroethane. The patients were divided into four groups in relation to the molar tooth: (1) mandibular first molar, (2) mandibular second molar, (3) maxillary first molar, and (4) maxillary second molar. 169 teeth and 676 sites were studied. (a) The most appropriate sites for cold test were the middle third of the buccal surface and cervical third of the buccal surface in the mandibular molars with the following results: Middle third of the first molar: Accuracy 0.93, positive predictive value 0.90 and negative predictive value 0.96. Middle third of the second molar: Accuracy 0.93, positive predictive value 1.00 and negative predictive value 0.90. In relation to third cervical the results were: First molar: Accuracy 0.93, positive predictive value 0.89 and negative predictive value 0.97 y second molar: Accuracy 0.93, positive predictive value 1.00 and negative predictive value 0.90. (b) The highest reproducibility was observed in the middle third of the buccal surface with cervical third of the buccal surface in the mandibular second molar (1.00). The most appropriate site and reproducibility of the sites are auxiliary to complement endodontic diagnose with the cold test.

Resumen Una prueba frecuentemente utilizada para complementar los diagnósticos endodónticos es la prueba de frío. Sin embargo, en los últimos 20 años, los autores han reportado resultados incorrectos con las pruebas de sensibilidad pulpar. Específicamente, se ha observado una alta frecuencia de resultados falsos en dientes posteriores. El objetivo del estudio fue identificar el sitio más adecuado para la prueba de frío en dientes molares con necesidad de tratamiento endodóntico, calculando valores predictivos, exactitud y reproducibilidad. Se realizó un estudio transversal donde se evaluaron a 390 sujetos. 152 sujetos de ambos sexos de 15 a 65 años cumplieron con los criterios de inclusión. El estándar ideal que se utilizó en el estudio fue la inspección directa de pulpa en la cámara pulpar y la prueba de frío utilizada fue el 1,1,1,2-tetrafluoroetano. Los pacientes fueron divididos en cuatro grupos en relación al diente molar: (1) primer molar mandibular, (2) segundo molar mandibular, (3) primer molar maxilar, y (4) segundo molar maxilar. En el estudio se evaluaron 169 dientes con 676 sitios. (a) Los sitios más adecuados para la prueba de frío fueron el tercio medio y el tercio cervical de la superficie bucal en los molares mandibulares con los siguientes resultados: Tercio medio del primer molar: Exactitud 0.93, valor predictivo positivo 0.90 y valor predictivo negativo 0.96. Tercio medio del segundo molar: Exactitud 0.93, valor predictivo positivo 1.00 y valor predictivo negativo 0.90. En relación al tercio cervical los resultados fueron: Primer molar: Exactitud 0.93, valor predictivo positivo 0.89 y valor predictivo negativo 0,97 y segundo molar: Exactitud 0.93, valor predictivo positivo 1.00 y valor predictivo negativo 0.90. (b) La más alta reproducibilidad (1.00) se observó entre el tercio medio con el tercio cervical de la superficie bucal en el segundo molar inferior. El sitio más apropiado y la reproducibilidad de los sitios son auxiliares para complementar el diagnóstico endodóntico con la prueba de frío.

Effects of silver nanoparticles on the bonding of three adhesive systems to fluorotic enamel.

The objective was to evaluate the effect of adding silver nanoparticles into three commercial adhesive systems (Excite™, Adper Prompt L-Pop™ and AdheSE™). Nanoparticles were prepared by a chemical method then mixed with the commercial adhesive systems. This was later applied to the fluorotic enamel, and then micro-tensile bond strength, contact angle measurements and scanning electron microscopy observations were conducted. The commercial adhesive systems achieved the lowest micro-tensile bond strength (Excite™: 11.0±2.1, Adper Prompt L-Pop™: 14.0±5.4 and AdheSE™: 16.0±3.0 MPa) with the highest adhesive failure mode related with the highest contact angle (46.0±0.6º, 30.0±0.5º and 28.0±0.4º respectively). The bond strength achieved in all the experimental adhesive systems (19.0±5.4, 20.0±4.0 and 19.0±3.5 MPa respectively) was statistically higher (p<0.05) than the control and showed the highest cohesive failures related to the lowest contact angle. Adding silver nanoparticles in order to decrease the contact angle improve the adhesive system wetting and its bond strength.

Efecto del blanqueamiento y el remineralizante sobre la microdureza y micromorfología del esmalte dental / Effect of whitening and remineralizing agent on the microhardness and micromorphology of dental enamel

Diversos estudios han demostrado mayor o menor grado de afectacióndel esmalte después del uso de los distintos tratamientos para blanqueamiento dental. Por este motivo, se han propuesto varios métodos ytratamientos remineralizantes que pudieran revertir los efectos negativosde dicho tratamiento. El objetivo del presente trabajo fue evaluar el efecto del Opalescence PF 15 por ciento (peróxido de carbamida al 15%) y delremineralizante Flor-Opal (NaF al 1.1 por ciento), ambos de la casa comercialUltradent, así como de la saliva artifi cial sobre la microdureza y la micromorfología del esmalte humano. Se utilizaron 10 incisivos centrales superiores recién extraídos provenientes de centros de salud del Puerto de Veracruz, México. Réplicas de estos dientes fueron obtenidas en lasdiferentes fases del tratamiento de blanqueamiento para ser posteriormente observadas en el microscopio electrónico de barrido (MEB). Asimismo, se realizaron mediciones de microdureza en la superficie del esmalte de los dientes seleccionados durante las diferentes fases del tratamiento de blanqueamiento. Se observó que la microdureza del esmalte se ve disminuida (aunque no significativamente) después de la aplicación del peróxido de carbamida al 15 por ciento, y vuelve a subir después de la aplicación de los remineralizantes, para posteriormente volver a descender siete días después del uso de los mismos. Los datos de microdureza coincidieron con los de micromorfología obtenidos enel MEB. Se concluye que el peróxido de carbamida al 15 opr ciento sí afecta lamicromorfología de la superficie del esmalte, además de que disminuyela microdureza del mismo. Con el uso del remineralizante Flor-Opal se onsiguieron mayores valores de microdureza y mejores características micromorfológicas comparado con la saliva artificial.

Studies have shown varying degrees of involvement of the enamel following the use of tooth-whitening treatments. Consequently, a range of methods and remineralizing treatments have been proposed to reverse their negative effects. The aim of this study was, therefore, to evaluate the effect of Opalescence PF 15% (carbamide peroxide 15%) and the remineralizing treatment Flor-Opal (1.1% NaF), both produced by Ultradent, as well as artifi cial saliva on the microhard-ness and micromorphology of human enamel. Ten recently-extracted central incisors from health centers in the port of Veracruz, Mexico, were used. Replicas of these teeth were made at the various stages of the whitening treatment in order to observe these under a scanning electron microscope (SEM). Microhardness measurements were also taken on the surface of the enamel of the teeth selected at each of the various stages of the whitening treatment. The microhardness of the enamel was found to decrease (though not signifi cantly) after the ap-plication of carbamide peroxide 15%, then increase again following the application of the remineralizing agents, only to decrease again seven days after these were applied. The microhardness data coincided with that for micromorphology obtained from the SEM. We conclude that carbamide peroxide 15% does affect the micromorphology of the enamel surface and also decreases its microhardness. Flor-Opal produced higher microhardness values and better micromorphological characteristics compared to artifi cial saliva.

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes.

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria.

Clinical evaluation of the accuracy of conventional radiography and apex locators in primary teeth.

PURPOSE: The purpose of this study was to clinically evaluate the accuracy of conventional radiography and 2 apex locators (Root ZX and ProPex) in determining the working length of root canals in primary teeth and to compare the results with scanning electron microscopy (SEM). METHODS: A general medical and oral history was obtained from 1,600 children and 50 children were selected. The working lengths of the primary teeth root canals were determined with conventional radiography and 2 apex locators (Root ZX and ProPex). These results were compared with the ideal standard using SEM. To determine the difference among means of the different methods, the Wilcoxon test was applied. To determine the accuracy of the methods with the ideal standard (SEM), the Lin interclass correlation coefficient (ICC) was used. RESULTS: Sixty-one canals were evaluated and there were no significant difference in the 3 techniques in accuracy of determination of the working length of the canals. The most accurate method of determining the working length of the root canals in primary teeth was the Root ZX (ICC=0.72), followed by the ProPex (ICC=0.70), and the least accurate was conventional radiography (ICC=0.67). CONCLUSION: The apex locators were more accurate than conventional radiography in determining the working length.