Physical properties, marginal adaptation and bioactivity of an experimental mineral trioxide aggregate-like cement modified with bioactive materials.

PURPOSE: To evaluate the effect of adding wollastonite and bioactive glass to an experimental mineral trioxide aggregate-like cement (MTA) on the dimensional stability, compressive strength, solubility, bioactivity, and marginal adaptation by scanning electron microscopy (SEM) and X-ray diffraction (XRD). METHODS: Four groups were evaluated at 7, 14, and 21 days: MTA Angelus, experimental MTA-like cement (MTA Exp), BG10 (MTA Exp+10 wt% bioactive glass), and WO20 (MTA Exp+20 wt% wollastonite). To evaluate marginal adaptation, extracted teeth were endodontically obturated and root-end cavities were prepared and filled with the tested materials. RESULTS: Cements with bioactive materials showed minimal dimensional changes. Adding wollastonite or bioactive glass to MTA Exp reduces the compressive strength but does not affect solubility. Bismite (Bi2O3), larnite (Ca2SiO4), calcite (CaCO3) and carbonated hydroxyapatite (Ca5[PO4,CO3]3[OH]) were identified in the four cements; ettringite (Ca6Al2[SO4]3[OH]12·26H2O) and bismutite ([BiO]2CO3) were only observed in MTA Exp, BG10, and WO20. Cement-dentin interfaces were not observed after 14 days on the BG10 and WO20 cement composites due to the ettringite formation. CONCLUSION: Acicular growing crystals typical of hydroxyapatite were found on the surfaces of all cements. An improved marginal adaptation was observed with the addition of wollastonite or bioactive glass.

Prevalence of three-rooted primary mandibular first and second molars: clinical and radiographic findings in a Mexican population.

The aim of this study was to determine prevalence and describe the clinical and radiographic findings of three-rooted primary mandibular first and second molars in a Mexican population. Intraoral periapical radiograph, orthopantomogram or cone beam computed tomography (CBCT) were obtained. A total 2284 children from the state of Puebla, Mexico were examined, of whom 20 presented an anatomic variant in tooth crown shape. Of the total teeth with crown alterations, 10 first and 5 second primary mandibular molars were found to have supernumerary roots. In one case, it was possible to obtain micro-CT images. The study recorded prevalence, unilateral or bilateral occurrence, and ratio between sexes. Data were analyzed using descriptive statistics. Clinical findings were presence of an anatomical variation (tuberculum paramolare / right and/or left cervical convexity) in primary mandibular first molars. Second molars presented conventional crown morphology. Prevalence of three-rooted primary mandibular first and second molars was 0.44% and 0.22%, respectively. Male: female ratio for presence of threerooted primary mandibular first molars was 4:1, showing genetic predisposition in males, and for second molars it was 1.5:1, with no predisposition according to sex. The clinical and radiographic anatomical variants in primary molars should be considered by pediatric dentists during routine care because they may cause difficulties in restorations.

El objetivo de este estudio fue determinar la prevalencia, así como los hallazgos clínicos y radiográficos de los primeros y segundos molares primarios mandibulares con tres raíces en una población mexicana. Se obtuvieron radiografías periapicales intraorales, ortopantomografía o tomografía computarizada de haz cónico (TCHC). Fueron revisados en total 2284 niños originarios del estado de Puebla, México, de los cuales 20 sujetos presentaron una variante anatómica en la forma de la corona dental. En el total de dientes con alteraciones coronarias, se encontraron 10 primeros y 5 segundos molares primarios mandibulares con raíces supernumerarias. En un caso fue posible la obtención de imágenes de micro tomografía computarizada (micro-CT). Fueron registradas la prevalencia, la ocurrencia uni o bilateral y la relación entre sexos. Los datos se analizaron mediante estadística descriptiva. Los hallazgos clínicos fueron: presencia de una variación anatómica (tuberculum paramolare / convexidad cervical derecha y/o izquierda) en los primeros molares primarios mandibulares. Los segundos molares presentaron una morfología coronal convencional. Entre los hallazgos radiográficos, fue común encontrar un conducto en cada raíz. La prevalencia fue de 0,44% y 0,22% para los primeros y segundos molares primarios mandibulares con tres raíces, respectivamente. La relación por sexo en los primeros molares primarios mandibulares con tres raíces fue de 4:1, indicando una predisposición genética para el sexo masculino, mientras que, en los segundos molares, la razón fue de 1,5:1 sin predisposición por sexo. Las variantes anatómicas clínicas y radiográficas presentes en los molares primarios deben ser tomadas en cuenta por los odontopediatras durante su rutina de atención, ya que pueden ocasionar dificultades para la restauración.

Prevalence of three-rooted primary mandibular first and second molars / Prevalencia de primeros y segundos molares primarios mandibulares con tres raíces

ABSTRACT The aim of this study was to determine prevalence and describe the clinical and radiographic findings of three-rooted primary mandibular first and second molars in a Mexican population. Intraoral periapical radiograph, orthopantomogram or cone beam computed tomography (CBCT) were obtained. A total 2284 children from the state of Puebla, Mexico were examined, of whom 20 presented an anatomic variant in tooth crown shape. Of the total teeth with crown alterations, 10 first and 5 second primary mandibular molars were found to have supernumerary roots. In one case, it was possible to obtain micro-CT images. The study recorded prevalence, unilateral or bilateral occurrence, and ratio between sexes. Data were analyzed using descriptive statistics. Clinical findings were presence of an anatomical variation (tuberculum paramolare / right and/or left cervical convexity) in primary mandibular first molars. Second molars presented conventional crown morphology. Prevalence of three-rooted primary mandibular first and second molars was 0.44% and 0.22%, respectively. Male: female ratio for presence of threerooted primary mandibular first molars was 4:1, showing genetic predisposition in males, and for second molars it was 1.5:1, with no predisposition according to sex. The clinical and radiographic anatomical variants in primary molars should be considered by pediatric dentists during routine care because they may cause difficulties in restorations.

RESUMEN El objetivo de este estudio fue determinar la prevalencia, así como los hallazgos clínicos y radiográficos de los primeros y segundos molares primarios mandibulares con tres raíces en una población mexicana. Se obtuvieron radiografías periapicales intraorales, ortopantomografía o tomografía computarizada de haz cónico (TCHC). Fueron revisados en total 2284 niños originarios del estado de Puebla, México, de los cuales 20 sujetos presentaron una variante anatómica en la forma de la corona dental. En el total de dientes con alteraciones coronarias, se encontraron 10 primeros y 5 segundos molares primarios mandibulares con raíces supernumerarias. En un caso fue posible la obtención de imágenes de micro tomografía computarizada (micro-CT). Fueron registradas la prevalencia, la ocurrencia uni o bilateral y la relación entre sexos. Los datos se analizaron mediante estadística descriptiva. Los hallazgos clínicos fueron: presencia de una variación anatómica (tuberculum paramolare / convexidad cervical derecha y/o izquierda) en los primeros molares primarios mandibulares. Los segundos molares presentaron una morfología coronal convencional. Entre los hallazgos radiográficos, fue común encontrar un conducto en cada raíz. La prevalencia fue de 0,44% y 0,22% para los primeros y segundos molares primarios mandibulares con tres raíces, respectivamente. La relación por sexo en los primeros molares primarios mandibulares con tres raíces fue de 4:1, indicando una predisposición genética para el sexo masculino, mientras que, en los segundos molares, la razón fue de 1,5:1 sin predisposición por sexo. Las variantes anatómicas clínicas y radiográficas presentes en los molares primarios deben ser tomadas en cuenta por los odontopediatras durante su rutina de atención, ya que pueden ocasionar dificultades para la restauración.

The presence of sinapyl lignin in Ginkgo biloba cell cultures changes our views of the evolution of lignin biosynthesis.

Suspension cell cultures (SCCs) from one of the oldest seed plants, Ginkgo biloba, show unpredictable alterations in the nature of the lignins, such as is the recruitment of sinapyl alcohol for lignin biosynthesis, compared with the woody tissues of the same species, which lack syringyl (S) lignins. These results show that, in this gymnosperm, the genes involved in sinapyl alcohol biosynthesis are latent and that their regulatory regions respond, by initiating gene expression, to the developmental signals and the environmental clues, which condition its in vitro culture. G. biloba SCCs not only synthesize S lignins but also their extracellular proteome contains both class III peroxidases capable of oxidizing sinapyl alcohol and enzymes involved in H2O2 production, observation which suggests that the peroxidase branch for the oxidative coupling of sinapyl alcohol units into lignins is operative. The incomplete knowledge of the G. biloba peroxidase-encoding genes led us to purify, characterize and partially sequence the peroxidase responsible for monolignol oxidation. When the major peroxidase from G. biloba SCCs (GbPrx) was purified to homogeneity, it showed absorption maxima in the visible region at 414 (Soret band), and at 543 and 570 nm, which calls to mind those shown by low-spin ferric peroxidases. However, the results also showed that the paraperoxidase-like character of GbPrx is not an obstacle for oxidizing the three monolignols compared with high-spin ferric peroxidases. Taken together, these results mean that the time at which the evolutionary gain of the segment of the route that leads to the biosynthesis of S lignins took place in seed plants needs to be revised.

Structural motifs of syringyl peroxidases are conserved during angiosperm evolution.

The most distinctive variation in the monomer composition of lignins in vascular land plants is that between the two main groups of seed plants. Thus, whereas gymnosperm (softwood) lignins are typically composed of guaiacyl (G) units, angiosperm (hardwood) lignins are largely composed of similar levels of G and syringyl (S) units. However, there are some studies that suggest that certain angiosperm peroxidases are unable to oxidize sinapyl alcohol, and a coniferyl alcohol shuttle has been proposed for oxidizing S units during the biosynthesis of lignins. With this in mind, a screening of the presence of S peroxidases in angiosperms (including woody species and forages) was performed. Contrarily to what might be expected, the intercellular washing fluids from lignifying tissues of 25 woody, herbaceous, and shrub species, belonging to both monocots and dicotyledons, all showed both S peroxidase activities and basic peroxidase isoenzymes analogous, with regard the isoelectric point, to the Zinnia elegans basic peroxidase isoenzyme, the only S peroxidase that has been fully characterized. These results led to the protein database in the search for homologies between angiosperm peroxidases and a true eudicot S peroxidase, the Z. elegans peroxidase. The findings showed that certain structural motifs of S peroxidases are conserved within the first 15 million years of angiosperm history, because they are found in peroxidases from the two major lineages of flowering plants, eumagnoliids and eudicotyledons, of note being the presence of these peroxidases in Amborella and Nymphaeales, which represent the first stages of angiosperm evolution. These phylogenetic studies also suggest that guaiacyl peroxidases apparently constitute the most "evolved state" of the plant peroxidase family evolution.

Changes in stem lignins (monomer composition and crosslinking) and peroxidase are related with the maintenance of leaf photosynthetic integrity during Verticillium wilt in Capsicum annuum.

• Verticillium dahliae is a soilborne pathogen that causes vascular wilt in pepper (Capsicum annuum var. annuum). Here we study to what extent changes in the lignification response of peppers condition tolerance of wilt. • For this, the quantum yield (ΦPSII ), the linear electron transport rate (ETR), and the lignification response (monomer composition and crosslinking) were studied in three C. annuum cultivars differing in degree of tolerance. • The results showed that in tolerant cultivars (Padrón and Yolo Wonder), both ΦPSII and ETR showed significantly higher levels at saturating photosynthetically active radiation values. This was not, however, the case for cv. Luesia, which showed a significant decrease in ΦPSII , ETR and nonphotochemical quenching values, suggesting that photochemical processes are strongly damaged in this cultivar as a consequence of the disease. The analysis of stem lignins in tolerant cultivars revealed that they were mainly composed of p-hydroxyphenyl units, while levels of ß-O-4-linked coniferyl and sinapyl alcohols were significantly lower. • It is concluded that through the observed changes in stem lignins (monomer composition and crosslinking) peppers retard, since they maintain leaf photosynthetic integrity, but do not stop (since wilt symptoms are not avoided) V. dahliae fungal hyphae penetration.

Capsaicinoids in vegetative organs of Capsicum annuum L. in relation to fruiting.

Pepper (cv. Padrón) shows a spatial gradient in the content of phenolic compounds, and particularly of capsaicinoids, along the stem. These compounds were consistently more abundant in apical fruits than in fruits belonging to middle and basal segments. Analysis of the two principal capsaicinoids in fruits showed that the proportion of capsaicin was always higher than that of dihydrocapsaicin. Capsaicinoids were also found to be present in vegetative organs, such as stem and leaves. In this case, the proportion of individual capsaicinoids was different than that in fruits, and dihydrocapsaicin was found to be more abundant. To find out whether the capsaicinoids in vegetative organs came from the fruits, the floral buds were removed and fruit formation was prevented. Capsaicinoids were not detected in the stem and leaves of floral bud-deprived plants, suggesting that they did originate from the fruit.

Realidad de la Conductometria Tentativa / Reality of the Attempt of Conduct Measurement

La finalidad de esta tesis de grado, es la de aportar a la odontologia en su area de endodoncia un estudio sobre la realidad de la ocnductometria tentativa, ya que son muy pocas las investigaciones que se conocen sobre el tema y consideramos de vital importancia su amplio conocimiento ya que la toma de una conductometria exacta es la base del exito del tratamiento endodontico. El estudio esta basado en un metodo clinico de recoleccion de datos, los cuales fueron tomados de pacientes atendidos en la clinica de adultos de la Fundacion Universitaria San martin y en Brigadas de Salud hechas en el municipio de Sibate. El informe consta de 9 capitulos los cuales sintetizamos a continuacion: 1-Anatomia del diente. En este capitulo se describe la anatomia y numero de los dientes permanentes. 2-Anatomia, histologia y fisiologia de la pulpa. En este capitulo se describen las funciones, desarrollo, anatomia, irrigacion, histologia y fisiologia de la pulpa. 3-Radiologia en endodoncia. En este capitulo se resumen los conceptos basicos de la radiologia, las sugerencias para la toma de radiografias en endodoncia y los errores en los que se puede incurrir. 4-Apertura en endodoncia. En este capitulo hablaremos de los objetivos de la apertura, tecnica general para la preparacion de acceso, la forma de apertura de cada diente, asi como los errores que se cometen. 5-Importancia de la conductometria en endodoncia. En este capitulo hablaremos de la importancia que tiene la conductometria en el tratamiento radicular - teniendo (RESUMEN TRUNCADO EN 1650 CARACTERES)..