Análisis geométrico de la arquitectura trabecular de un hueso de bovino durante el proceso inducido de desmineralización / Geometric analysis of the trabecular architecture in a bovine bone during the process of induced demineralization

La masificación de la radiología digital ha hecho posible el estudio de diferentes patologías mediante imágenes de alta calidad diagnóstica. Existen diferentes patologías que afectan al tejido óseo, y que producen pérdida del mineral(1). Aquellas patologías se caracterizan por la pérdida de la arquitectura trabecular y un adelgazamiento de la cortical(7), visibles en la radiología. Aquellos cambios llevan al paciente a caer en el riesgo de sufrir futuras fracturas(8), por lo que se considera importante realizar un análisis de la geometría de las trabéculas ante este tipo de patología, con el fin de prever riesgos de fractura. Material y Métodos. Para realizar este estudio, se escogió un fémur de bovino(19). Este fue sumergido en ácido acético al 4 por ciento, con el fin de producir su desmineralización. Se le realizó una medición cada 24 horas mediante la adquisición de imágenes radiológicas, que fueron obtenidas con un equipo digital directo hasta observar cambios radiológicos evidentes en la población trabecular. Las imágenes fueron evaluadas mediante un software de libre acceso llamado ImageJ®(23), realizando mediciones trabeculares mediante la herramienta ROI, y se adquirieron los valores de área, perímetro y circularidad. Resultados. En las 10 trabéculas estudiadas se observaron y cuantificaron cambios en la arquitectura trabecular, aumentando el área en un 124 por ciento, el perímetro en un 53 por ciento y la circularidad se mantuvo en promedio constante. Conclusiones: Mediante la radiología digital, es posible evaluar la arquitectura trabecular mediante parámetros geométricos, los cuales nos indican que existen cambios muy pequeños a lo largo del tiempo. Se observó un aumento de tamaño en las trabéculas, pero sin pérdida de su forma.

Introduction. The mass use of digital radiology has made possible the study of different pathologies through high quality diagnostic images. There are different diseases that affect bone tissue and which produce mineral loss (1). Those diseases are characterized by loss of trabecular architecture and cortical thinning (7), visible in radiology. Those changes lead the patient to suffer the risk of future fractures (8), therefore it is considered important to analyze the geometry of the trabeculae in this kind of pathology in order to anticipate fracture risk. Material and Methods. For this study, a bovine's femur was chosen(19). This was immersed in 4 percent acetic acid to produce demineralization. Measurement was performed (in Clinica Alemana Santiago) every 24 hours by radiological imagings, which were obtained with digital radiology (DR) to observe obvious radiological changes in trabecular population. The images were evaluated by a freely available software called ImageJ® (23), by performing Trabecular measurements using the ROI tool, acquiring the values of area, perimeter and circularity. Results. In the 10 trabeculae studied, we observed and quantified changes in trabecular architecture, increasing the value of average area in 124 percent, perimeter in 53 percent and no change in circularity during the demineralization process. Conclusions. With digital radiography, it is possible to evaluate the trabecular architecture using geometric parameters, which indicate that there are very small changes over time. An increase in size of the trabeculae was observed, trabeculae was observed, but without loss of shape.

Time-dependent decalcifying effects of endodontic irrigants with antibacterial properties.

The aim of this study was to investigate the extent of calcium ion (Ca(2+)) removal on root dentin after treatment with 1.25% NaOCl, 2.5% NaOCl, 5.25% NaOCl, 2% chlorhexidine (CHX), 2% iodine potassium iodide (IKI), and MTAD in 3 immersion time periods. Extracted human mandibular premolars were bisected longitudinally, and the root halves (n = 70) were isolated with nail varnish, leaving the root canal exposed. The specimens were immersed in the test solutions, during which the amount of Ca(2+) release into the solutions was determined at 5, 10, and 15 minutes by flame photometry. The decalcifying effect of 5%, 2.5%, and 1.25% NaOCl and 2% IKI significantly increased within time (P < .05), with 5% NaOCl extracting the greatest amount of Ca(2+) at all treatment times. For 2% CHX and distilled water, a significant increase in the amount of Ca(2+) extraction from root dentin was only evident at 10 minutes (P < .05) and did not change at 15-minute readings. Between the 5- to 10-minute and 10- to 15-minute intervals, the greatest amount of increase in the rate of Ca(2+) extraction from root dentin was observed in the 2.5% NaOCl group. At 15 minutes, 2% CHX and distilled water showed the least amount of change. Among the test solutions, MTAD extracted the least amount of Ca(2+) at 5 minutes.

Histometric study of alveolar bone in rats submitted to ethanol during lactation

The present work studied the adverse effects of maternal exposure of rats to alcohol during lactation, on the development of their off spring. Histometric evaluation by karyometry and of the alveolar bone at the level of the first upper molar of the sucking was perfomed. Two groups of animals, one coming from mothers exposed to drinking water containing 20 percent ethanol during the total lactation period and the other of controls coming from mothers receiving only alcohol-free drinking water during this period. On the 21 first day of lactation the young of each group were aleatorily selected and following anesthesia, their heads severed; after histological treatment, serial 6 ìm sections on the frontal plane at the molar level, stained with hematoxilin and eosin, were obtained. The experimental results produced, suggest that sucking from ethanol-treated mothers, show retarded post-natal growth, their alveolar bones presenting scarce, little calcified trabeculae, and a more abundant bone marrow compared to controls.

Considerando que la lactancia es un período importante y vulnerable, y que la exposición materna al alcohol durante esta fase puede provocar efectos adversos en las crías en desarrollo, el propósito del presente trabajo es evaluar histométricamente (mediante cariometría y estereología), el hueso alveolar a nivel del primer molar superior, de ratas lactantes sometidas a los efectos del etanol. Con esa finalidad utilizamos dos grupos, uno que recibió etanol al 20 por ciento en el bebedero, durante todo el período de lactancia (21días), y otro que recibió solo agua. En el 21° día de lactancia, 5 ratas de cada grupo fueron aleatoriamente seleccionadas. Después de sacrificados, los animales fueron fijados en formol al 10 por ciento. Las cabezas, separadas de los cuerpos, fueron incluidas en parafina, y cortadas seriadamente con 6 Lim de grosor, a partir de un plano frontal al nivel de los molares, y teñidas con hematoxilina y eosina. Basados en los resultados presentes, es posible concluir que el etanol al 20 por ciento en el agua de beber, administrado a ratas lactantes, provoca los siguientes efectos: reducción significativa del peso corporal, alteraciones de las trabéculas del hueso alveolar, observadas estereológicamente, evidenciadas por trabéculas delicadas y poco calcificadas, con médula abundante, núcleos menores en osteoblastos y osteocitos y más achatados en los primeros, y con osteocitos de volúmenes citoplasmático y celular menor y densidad numérica mayor.

[In vitro experiments on effect of soft drinks on dental enamel]. / In-vitro-Experimente über die Auswirkungen von Erfrischungsgetränken auf die Zahnhartsubstanz.

The composition and dental properties of eight different soft drinks, representing some of the most popular types used in the U.K., were examined. Demineralisation experiments were conducted on hydroxylapatite, the basic component of dental enamel, determining calcium dissolving by atomic absorption spectroscopy and phosphorus by UV/vis spectrophotometry. The titratable acid content of the drinks was found to give a better guide than their pH to their potential dental erosiveness. The sugars content, in their ready-to-drink form, varied from zero in a low-calorie product up to almost 14% in a black-currant drink, but using a technique with a relatively long contact time, and in the absence of intact dental plaque, the demineralising action on hydroxylapatite of the acids already in the drinks eclipsed the effects of the acid generated by oral micro-organisms from the sugars in the drinks. The pure citrus juices showed potentially the worst dental properties, followed by the orange and blackcurrant concentrates after dilution to their ready-to-drink form, with least demineralisation from the carbonated drinks, and a cola drink giving especially low figures.

Evaluation of factors associated with glucocorticoid-induced osteopenia in patients with rheumatic diseases.

In 161 ambulatory rheumatic disease patients receiving long-term prednisone therapy, diaphyseal mass (DM) and metaphyseal mass (MM) of the forearm were measured by single photon absorptiometry, and bone radiographs were reviewed when available. Multivariate analysis of treatment and patient characteristics demonstrated that glucocorticoid-induced osteopenia (defined as an elevated DM:MM ratio) and bone fractures occurred with similar frequency in patients of each sex, in whites and blacks, in patients with various rheumatic diseases, and in patients receiving different regimens of prednisone therapy. However, large cumulative doses of prednisone were associated with elevated DM:MM ratios as well as with bone fractures, and menopause or age greater than or equal to 50 years (males or females) was associated with bone fractures. We conclude that long-term therapy with various prednisone regimens results in glucocorticoid-induced osteopenia and fractures. This affect is cumulative, occurs in all patient groups, and results in more bone fractures in certain groups.

Calmodulin activity in corticosteroid-induced osteopenia.

A reproducible high-pressure liquid chromatography assay of calmodulin, a multifunctional calcium-dependent modulating protein, was developed for cartilage and bone by using cyclic nucleotide phosphodiesterase activity as the basis for standard curve determination. Calmodulin activity was then measured in rabbits that were made osteopenic by prednisolone injection in an effort to characterize in vivo cellular events. A significant rise in bone calmodulin levels was noted when this data was correlated with osteocyte and osteoblast content by quantitative histomorphometry. This suggests that calmodulin mediates steroid effects on the collagen matrix as well as on calcium homeostasis. Diminished calmodulin levels in weight-bearing cartilage of steroid-treated animals has as yet unresolved significance. Further characterization of calmodulin activity appears warranted in the study of osteopenic states at the subcellular level.

Skeletal demineralization and growth retardation in inflammatory bowel disease.

Skeletal growth and mineralization in 54 adolescent and adult patients with inflammatory bowel disease have been analyzed comprehensively. Quantitative and qualitative radiologic techniques consisted of conventional roentgenography, photon absorptiometry, and radiographic morphometry. The data are correlated with the type, duration, and severity of disease, and with several modes of therapy. The results indicate the osteopenia and retardation of growth are common in patients with inflammatory bowel disease, particularly in adolescents, in whom the effects of corticosteroids on the skeleton are most deleterious.

Enamel demineralization by snack foods.

The amount of enamel destroyed by salivary fermentation of snack foods and confections was not dependent on their sugar content; starch, flavoring agents, and other components also played a part. Most enamel destruction was produced by fruit-flavored candies in which the inherent acid or high sugar concentration or both inhibited bacterial fermentation.