Bone substitute in the repair of the post-extraction alveolus.

In recent years there has been increasing interest in the choice of the best material for bone substitutes. Experimental models enable estimation of biological potential, efficacy and safety of a biomaterial before its clinical application. The aim of this study was to evaluate the response of a bone substitute, UNC bone matrix powder (MOeP-UNC), for repairing the post-extraction alveolus in Wistar rats. Rats' first lower molars were extracted. The right alveoli were filled with MOeP-UNC hydrated with physiological saline (Experimental Group, EG), and the left alveoli were used as Control Group (CG). Thirty days after extraction, the animals were killed and the samples processed. Histological sections were made in vestibular-lingual direction at the level of the mesial alveolus of the first inferior molar (Guglielmotti et al. J. Oral Maxillofac. Surg. 1985;43(5):359-364). Repair of the alveoli at 30 days after extraction was evaluated histologically. Repair of the alveolus was optimum in the control group at 30 days, and the EG showed presence of MOeP-UNC particles in close contact with newly formed bone tissue (osseointegration). In the experimental model used, at 30 days post-surgery, the MOeP-UNC particles integrate compatibly with newly formed bone tissue.

Bone substitute in the repair of the post-extraction alveolus

In recent years there has been increasing interest in the choice of the best material for bone substitutes. Experimental models enable estimation of biological potential, efficacy and safety of a biomaterial before its clinical application. The aim of this study was to evaluate the response of a bone substitute, UNC bone matrix powder (MOeP-UNC), for repairing the postextraction alveolus in Wistar rats. Rats' first lower molars were extracted. The right alveoli were filled with MOeP-UNC hydrated with physiological saline (Experimental Group, EG), and the left alveoli were used as Control Group (CG). Thirty days after extraction, the animals were killed and the samples processed. Histological sections were made in vestibular- lingual direction at the level of the mesial alveolus of the first inferior molar (Guglielmotti et al. J. Oral Maxillofac. Surg. 1985;43(5):359-364). Repair of the alveoli at 30 days after extraction was evaluated histologically. Repair of the alveolus was optimum in the control group at 30 days, and the EG showed presence of MOeP-UNC particles in close contact with newly formed bone tissue (osseointegration). In the experimental model used, at 30 days post-surgery, the MOeP-UNC particles integrate compatibly with newly formed bone tissue.

En los ultimos anos se ha incrementado el interes por la eleccion del material mas adecuado como sustituto oseo. Los modelos experimentales permiten estimar el potencial biologico, la eficacia y seguridad de un biomaterial, previo a su aplicacion clinica. El objetivo del presente estudio fue evaluar la respuesta de un sustituto oseo, matriz osea-UNC en polvo (MOeP-UNC), en la reparacion alveolar post-exodoncia en ratas Wistar. Se realizo la exodoncia de los primeros molares inferiores. En los alveolos derechos se coloco MOeP-UNC hidratada con solucion fisiologica (Grupo Experimental, GE). Los alveolos izquierdos, fueron utilizados como Grupo Control (GC). A los 30 dias post-exodoncia los animales fueron sacrificados y las muestras obtenidas se procesaron, se realizaron cortes histologicos en sentido vestibulo-lingual a la altura del alveolo mesial del primer molar inferior (Guglielmotti et al. J Oral Maxillofac Surg. 1985;43(5):359-364). Se realizo la evaluacion histologica de la reparacion de los alveolos a los 30 dias post cirugia. El grupo control presento una optima reparacion alveolar a los 30 dias y en el GE se evidencio la presencia de las particulas de MOeP-UNC en intimo contacto con el tejido oseo neoformado (oseointegracion). En el modelo experimental utilizado, a los 30 dias post-cirugia las particulas MOePUNC se integran de manera compatible con el tejido oseo neoformado.

Furcation groove of maxillary first premolar, thickness, and dentin structures.

INTRODUCTION: Few studies mention the presence of furcation grooves in the palatal aspect of buccal roots in upper first premolars. Anatomic characteristics like external grooves or root curvatures predispose teeth to weakening during post placement. Roots with a large number of external sulci show more canal variations. Previous research found that the palatal wall is on average less than 1mm. There is a direct relation between the volume of dental structures and the capacity to resist occlusal loads. The purpose of this study was to evaluate the changes in dentin thickness and structures adjacent to the furcal groove. METHODS: The percentage that represented furcation groove in the buccal root was specified. The sample size selected was n=20. Three horizontal slices were made to the buccal root, coronal, middle, and apical. The angles of the grooves and dentin thickness were measured with a profile projector. RESULTS: In the coronal third, the depth of the groove was correlative with dentin thickness negatively, ie, while the depth increased, palatal dentin thickness decreased or vice versa. In the coronal and middle thirds, the palatal wall showed average dentin width smaller than the buccal. In some cases, the thickness was less than 1mm. In the apical third, palatal dentin thicknesses showed higher averages than the buccal. Structural changes were observed in dentin adjacent to the furcation groove. These results are discussed in the context of other research. Methodologic differences do not enable comparative studies. CONCLUSIONS: Dentin thickness corresponding to the furcal groove is variable; it presents structural changes and must be taken into account in endodontic and prosthetic procedures.

Early phenotypic and genotypic alterations in submandibular gland oncogenesis in rats.

The present study evaluates the phenotypic and genotypic changes that take place during early oncogenesis. The submandibular glands of male rats were injected with a 0.5% solution of 9,10-dimethyl-1,2-benzanthracene (DMBA) in acetone. Gland samples were taken at 0, 7, 30 and 150 days post-injection and submitted to histological, biochemical, immunocytochemical and PCR evaluation. Histopathological analysis was performed on hematoxylin-eosin stained slides. Total protein content was assessed by Lowry's method and the protein profile was analyzed by 12% SDS-PAGE. Bcl-2 was demonstrated by silver-enhanced gold immunolabeling. p53 immunolabeling was performed using the streptavidin-biotin system. All the treated animals developed carcinoma-like lesions at 30 and 150 days. Total protein concentration rose significantly (p < 0.05) above control values at 7, 30 and 150 days. The treated glands exhibited positive immunolabeling for p53 in the nuclei of neoplastic cells at 30 and 150 days. Treated glands also showed positive cytoplasmic immunolabeling for Bcl-2, exhibiting statistically significant differences between 7, 30 and 150 days (p = 0.0015), and with controls (p < 0.0001). No p53 mutations were observed whereas a point mutation, C-to-A, of the Bcl-2 gene was detected at 7, 30 and 150 days by PCR amplification. This mutation led to a single aminoacid change (thre --> asn) in the protein molecule. Our results suggest that the early histopathological changes correspond to quantitative and qualitative protein changes. The histopathological, biochemical, immunocytochemical and genetic alterations observed during the course of experimental carcinogenesis in the submandibular gland of the rat could constitute reproducible indices of malignant transformation applicable to human oncogenesis, given the high degree of homology between the oncogenes of mice, rats and human beings.

Early phenotypic and genotypic alterations in submandibular gland oncogenesis in rats

Se evaluaron modificaciones del fenotipo y genotipo en glándulas submandibulares durante el desarrollo temprano de la tumorogénesis. Glándulas submandibulares de ratas macho fueron inyectadas con una solución de 0.5 por ciento de 9,10 dimetil 1,2-benzathracene (DMBA) diluida en acetona. Muestras de glándulas fueron analizadas mediante técnicas histológicas, bioquímicas, inmunocitoquímicas y por PCR a los 0, 7, 30 y 150 días postinyección. Para los estudios histopatológicos se utilizó la técnica de hematoxilina-eosina. Se determinó la concentración de proteínas totales por el método de Lowry y se realizaron corridas electroforéticas en gel de poliacrilamida SDS-PAGE al 12 por ciento para determinar el perfil proteico. Se realizó inmunomarcación para Bcl-2 con oro coloidal-plata y para p53 por streptavidina-biotina. Todos los animales tratados desarrollaron cambios similares a carcinomas a los 30 y 150 días. La concentracióan de proteínas totales aumentó significativamente (p<0,05) a los 7, 30 y 150 días en relación a los controles. En glándulas inducidas la inmunomarcación fue positiva para la proteína p53 en núcleos de células neoplásicas a los 30 y 150 días. En las mismas glándulas, la marcación citoplasmática de Bcl-2 fue positiva a los 7, 30 y 150 días(p=0,0015) y en relación a los controles (p<0,0001). No se observaron mutaciones de p53, mientras que se observó una mutación puntual, C A del gen bcl-2 a los 7, 30 y 150 días que generó un cambio de aminoácidos en la proteína (thre asn). Nuestros resultados sugieren que los cambios histopatológicos tempranos corresponden a modificaciones cuantitativas y cualitativas de las proteínas. Las modificaciones observadas a nivel histopatológico, bioquímico, inmunocitoquímico y genético en la carcinomgénesis experimental de glándula submandibular de rata podrían representar parámetros reproducibles de transformaciones malignas transferibles al ser humano, dada la alta homología de estos oncogenes entre rata, ratones...

Oral health and salivary factors in rural schoolchildren.

The aim of the present study was to assess the association between some salivary factors and the oral health status of rural schoolchildren of Córdoba (Argentina). The study involved 19 students (aged 5-14 years) who attended 8 rural schools of the region. We determined indices (r)dmf-t, (r)DMF-T and S-OHI. pH, salivary flow (vol/min), protein concentration, calcium and phosphate levels and the molar Ca/P ratio were evaluated in stimulated saliva. The arithmetic mean and standard error were assessed for each of the parameters. We employed the Principal Component Analysis (PCA) to assess the similarities and differences between salivary components for the splits (r)dmft = 0, (r)dmft > 0, (r)DMFT = 0 and (r)DMFT > 0. We observed a positive correlation (Spearman's coefficient, p < or = 0.05) between the concentration of proteins, calcium, phosphate and salivary flow. The mean values for the salivary parameters evaluated evidence differences in the oral health status between the different schools under study. In five of the schools evaluated, the variables that best explain the condition of caries disease were concentration of proteins, calcium, phosphate, and the Ca/P molar ratio. The variation observed in the oral health indicators, volume/minute and salivary components between schools evidences the need to perform individual studies for each school and consider the needs and possibilities of each community when designing programs to promote oral health.

Effect of platelet-rich plasma on the peri-implant bone response: an experimental study.

Platelet-rich plasma (PRP) is used as a source of growth factors to stimulate and accelerate bone formation and soft tissue healing. The use of PRP in bone regeneration, both around dental implants and in periodontic treatments, has become particularly appealing. The aim of this study was to evaluate the effect of PRP in an experimental model of osteogenesis around laminar implants. Fifteen male Wistar rats, weighing 90 +/- 10 g, were used in this study. One milliliter of blood was obtained from each animal by intracardiac puncture and transferred into Eppendorf tubes containing 10% sodium citrate. The tubes were centrifuged at 1500 rpm for 15 minutes and PRP was prepared. The laminar test was used to evaluate the bone peri-implant response. PRP and a titanium laminar implant were introduced into the right tibia (Ti/PRP group), whereas the left tibia (control) received only a laminar implant (Ti group). Thirty days postimplantation, the tibiae were resected, radiographed, and processed for embedding in acrylic resin. Ground sections (50 microm) were stained with toluidine blue. The peri-implant bone volume was evaluated histomorphometrically. Statistical analysis of the data was performed. The amount of newly formed bone in the Ti/PRP group (30 +/- 7 cm) was significantly greater than in the Ti group (16 +/- 3 cm). A greater volume of peri-implant bone was observed when PRP was used in the laminar implant test model.

Oral health and salivary factors in rural schoolchildren

El propósito del presente trabajo fue evaluar la asociación entre algunos factores salivales y el estado de salud bucodental de escolares rurales de Córdoba (Argentina). El estudio incluyó 199 alumnos entre 5 y 14 años de edad, asistentes a 8 escuelas de la región, determinándose los índice ceo-d(r) y CPO-D(r) y el índice IHO-S. En saliva estimulada se evaluó: pH, flujo salival (vol/min), concentración de proteínas, de calcio y de fosfato y la relación molar Ca/P. Para cada una de las variables se determinó media aritmética y error estándar. Se aplicó el análisis de componente principal (ACP) para explorar las similitudes y diferencias entre los componentes salivales para las categorías ceo-d(r) = 0, ceo-c(r) > 0, CPO-D(r) = 0 y CPO-D(r)>0. Se obsevó correlación positiva (coeficiente de Spearman, p>- 0.05) entre las concentraciones de proteínas, calcio, fosfato y flujo salival. Los valores medios de las variables salivales estudiadas muestran diferencias entre las distintas comunidades escolares, relacionadas con el estado de salud dental de las mismas. En cinco de las ocho excuelas investigadas las variables que mejor explican la condición de enfermedad de caries son concentración de proteínas, calcio, fosfato yla retención molar Ca/P. La variabilidad observada en los indicadores de salud dental, en el volúmen/minuto y en los componentes salivales entre escuelas, evidencia la necesidad de realizar análisis individualizados para cada escuela al momento de diseñar programas de promoción de salud bucal, que respeten las necesidades y posibilidades de cada comunidad.

Effect of low-power radiation (helium/neon) upon submandibulary glands.

OBJECTIVE: The aim of this work was to study the effect of low-power laser radiation on guinea pig salivary glands. BACKGROUND DATA: Low-power laser radiation changes some cellular functions. The effect on salivary glands has not been sufficiently studied. MATERIALS AND METHODS: One hundred and forty-four male guinea pigs (150 +/- 30 g body weight) were used. The animals were divided into two groups: control group (fed animals and those undergoing 2, 4, 8, 10, and 12 h of fasting) and experimental group (irradiated). Both the right and left submandibular glands were later irradiated with helium-neon laser at 7-mW power, with a 0.75-mm spot, under continuous pulse for 2 min in a one-session exposure; a 11.2 J/cm(2) energy density was applied. Then, the irradiated animals were fed, or underwent 2, 4, 8, 10 and 12 h of fasting. Samples of submandibular glands were taken with a punch (5 mm diameter) and were used for optic and transmission electron microscopy studies. RESULTS: The structural observations showed that the irradiation effect was progressive; and showed a trophic stimulant effect at 2 h following irradiation, with vasodilatation, vascular congestion, perivascular infiltrate, and a necrotic picture of glandular parenchyma at longer times. The ultrastructural observations showed alterations of rough endoplasmic reticulum. CONCLUSION: We propose that low-power laser radiation with the doses applied in this study disturbs protein synthesis and secretion of guinea pig submandibulary glands.

Effects induced by isoproterenol during synthesis and secretion of the parotid gland: experimental structural studies

The effect of isoproterenol, a â-adrenergic agonist, on the parotid gland of guinea pig was studied in vivo. Male guinea pigs were fasted 12 h, and then injected intraperitoneally with isoproterenol (30 mg/kg). The parotid glands were processed for light and transmission electron microscopy using conventional techniques. Morphological analysis showed massive granular secretion 2 h after isoproterenol injection and an enlarged apical surface of the plasma membrane, as indicated by the presence of microvilli. Twenty-four hours after injection of isoproterenol the gland had still not returned to its pre-stimulation state. The effect of isoproterenol decreased with time and the apical surface of the plasma membrane eventually resumed its normal (basal) appearance. These data showed that the maximum secretagogue effect of isoproterenol on parotid gland of guinea pig was evident 2 h after injection and decreased according to the time.

Adaptación a las paredes cavitarias de incrustaciones metálicas y de resinas / Adaptation to wall cavities of metal and resin inlays

El propósito del siguiente trabajo fue investigar la adaptación de las incrustaciones metálicas comparadas con incrustaciones de resinas directas. En premolares extraídos por razones periodontales se realizaron cavidades mesiooclusodistales de características semejantes que fueron restaurados respetando las normas e indicaciones de diferentes materiales. Un grupo fue restaurado con incrustaciones metálicas y otro con incrustaciones de resinas directas. Las mediciones se efectuaron en tres sectores diferentes y se observaron en microscopio electrónico de barrido marca Phillips 500 B. Los datos fueron comparados estadísticamente. Los elementos dentarios restaurados con incrustaciones de resinas directas mostraron una mejor adaptación a las paredes cavitarias mostrando diferencias estadísticamente significativas cuando se comparan las incrustaciones metálicas

Resistencia traccional de incrustaciones metálicas y de resinas / Tensile strenght of metallic and resin inlays

El propósito de este trabajo fue efectuar un estudio comparativo de la resistencia traccional en incrustaciones metálicas y de incrustaciones de resinas directas. En premolares superiores sanos se realizaron cavidades mesiooclusodistales de características semejantes y fueron restaurados de la siguiente manera. Un grupo, con incrustaciones metálicas convencionales, cementadas con cemento de fosfato de zinc y otro grupo con incrustaciones de resinas directas, cementadas con un cemento resinoso. Todos los dientes fueron colocados en una máquina Instron TT.CM de compresión tracción hasta lograr la fractura del sistema diente-restauración. Las fuerzas medias requeridas en los dos grupos fueron comparadas estadísticamente. Los dientes restaurados con incrustaciones de resina directa cementados con un cemento resinoso demostraron una mayor resistencia traccional ofreciendo una diferencia estadísticamente significativa que el grupo de incrustaciones metálicas convencionales, cementadas con cemento de fosfato de zinc

Caracterización estructural y citoquimica de las glandulas salivales de ratas adrenalectomizadas / Structural and cytochemical characterization of the salivary glands of adrenalectomized rats

Considerando que el rol de ciertas hormonas adrenales sobre las glándulas salivales no ha sido suficientemente aclarado, decidimos el estudio de los cambios estructurales y citoquímicos que la adrenalectomía causa sobre estos órganos. El estudo estructural y citoquímico en submaxilar muestra modificaciones del parénquima glandular. Estos cambios se mantienen desde 7 hasta 45 días. No se encouetran alteraciones significativas en sublingual. Los resultados obtenidos sugieren que se producirían modificaciones en los productos de secreción de estas glándulas