Histomorphometric evaluation of the effects of mandibular advancement appliance and low level laser therapy (LLLT) with different doses on condylar cartilage and subchondral bone in rats / Evaluación histomorfométrica de los efectos del aparato de avance mandibular y la terapia con láser de bajo nivel (TLBN) con diferentes dosis en cartílago condilar y hueso subcondral en ratas

The aim of this study was to evaluate the effects of mandibular advancement appliance and low level laser therapy (LLLT) with different doses on cellular hypertrophic changes in the mandibular condyle of rats. Forty-eight 8-week-old male Wistar albino rats weighing between 260 and 280 g were randomly divided into four experimental and control groups. Group I was the control group; group II was the mandibular advancement appliance group; group III was the 8 J/cm2 (0.25 W, 20 s) laser irradiation with mandibular advancement appliance group; and group IV was the 10 J/cm2 (0.25 W, 25 s) laser irradiation with mandibular advancement appliance group. Mandibular condyle cartilage and subchondral bone changes with different LLLT dose and mandibular advancement appliance were evaluated by histomorphometrical analysis. Subchondral bone fraction results showed that there were no significant differences between groups (p<0.05). The statistically significant differences found between control group and experimental groups in anterior and posterior cartilage layers thickness (p<0.05) and (p<0.01). Posterior and anterior condylar cartilage layers of rats react differentially to LLLT and mandibular advancement application. Maximum changes in condylar cartilage layers were found in 8 J/cm2 laser irradiation with mandibular appliance group.

El objetivo de este estudio fue evaluar los efectos del aparato de avance mandibular y la terapia con láser de bajo nivel (TLBN) con diferentes dosis sobre los cambios hipertróficos celulares, en el cóndilo mandibular de ratas. Cuarenta y ocho ratas albinas macho Wistar de 8 semanas de edad con un peso de 260 y 280 g se dividieron aleatoriamente en cuatro grupos experimentales y control. El grupo I control; grupo II, dispositivos de avance mandibular; grupo III de irradiación con láser de 8 J / cm2 (0.25 W, 20 s) con el grupo dispositivos de avance mandibular; y grupo IV con irradiación láser de 10 J / cm2 (0,25 W, 25 s) con el grupo de dispositivos de avance mandibular. El cartílago del cóndilo mandibular y los cambios en el hueso subcondral con diferentes dosis de TLBN y dispositivo de avance mandibular, se evaluaron mediante análisis histomorfométrico. Los resultados de la fracción ósea subcondral indicaron que no hubo diferencias significativas entre los grupos (p <0,05). Las diferencias estadísticamente significativas encontradas entre el grupo control y los grupos experimentales, en el grosor del cartílago anterior y posterior (p<0,05) y (p<0,01). Las capas de cartílago condilar posterior y anterior de las ratas reaccionan de manera diferencial a la aplicación de TLBN y avance mandibular. Se encontraron cambios significativos en las capas de cartílago condilar con irradiación láser de 8 J /cm2 con el grupo de dispositivos mandibulares.

Biomechanical and morphological changes produced by ionizing radiation on bone tissue surrounding dental implant

Abstract Objective: This study analyzed the effect of ionizing radiation on bone microarchitecture and biomechanical properties in the bone tissue surrounding a dental implant. Methodology: Twenty rabbits received three dental morse taper junction implants: one in the left tibia and two in the right tibia. The animals were randomized into two groups: the nonirradiated group (control group) and the irradiated group, which received 30 Gy in a single dose 2 weeks after the implant procedure. Four weeks after the implant procedure, the animals were sacrificed, and the implant/bone specimens were used for each experiment. The specimens (n=10) of the right tibia were examined by microcomputed tomography to measure the cortical volume (CtV, mm3), cortical thickness (CtTh, mm) and porosity (CtPo, %). The other specimens (n=10) were examined by dynamic indentation to measure the elastic modulus (E, GPa) and Vickers hardness (VHN, N/mm2) in the bone. The specimens of the left tibia (n=10) were subjected to pull-out tests to calculate the failure load (N), displacement (mm) up to the failure point and interface stiffness (N/mm). In the irradiated group, two measurements were performed: close, at 1 mm surrounding the implant surface, and distant, at 2.5 mm from the external limit of the first measurement. Data were analyzed using one-way ANOVA, Tukey's test and Student's t-test (α=0.05). Results: The irradiated bone closer to the implant surface had lower elastic modulus (E), Vickers hardness (VHN), Ct.Th, and Ct.V values and a higher Ct.Po value than the bone distant to the implant (P<0.04). The irradiated bone that was distant from the implant surface had lower E, VHN, and Ct.Th values and a higher Ct.Po value than the nonirradiated bone (P<0.04). The nonirradiated bone had higher failure loads, displacements and stiffness values than the irradiated bone (P<0.02). Conclusion: Ionizing radiation in dental implants resulted in negative effects on the microarchitecture and biomechanical properties of bone tissue, mainly near the surface of the implant.

Apoptosis in bone defect of diabetic rats treated with low intensity laser: radiological and immunohistochemical approach / Apoptosis en ratones diabéticos con defecto oseo tratados con láser de baja intensidad: evaluación radiológica e inmunohistoquímica

The aim of this study is evaluate the efficacy of 904 nm laser diode in bone regeneration in the bone defect in diabetic rats. Six groups of 10 male Wistar rats and 2 mm bone defects drilled on the left and right tibia were used. The diabetic animals were treated with streptozotocin (40 mg/kg, i.v.). We compared the diode laser doses of treatment of bone defects 50 w ­ 4 J/cm and 100 w ­ 4J/. The right tibia was used for immunohistochemical analysis with the apoptosis markers XIAP and Caspase-3 and the left tibia was submitted to computer tomography (CT). Caspase-3 marker showed greater amount of apoptosis in all the untreated groups compared to both laser treatments. There was no statistical significance for XIAP marker. CT scan showed improvement of bone defect area and volume in both laser treated groups, control and diabetic. Therefore the low intensity laser therapy was effective in accelerating bone repair in both, control and diabetic groups. It was evidenced in our study that diabetes influences bone repair negatively.

Los objetivos de este estudio fueron evaluar la eficacia del láser diodo de 904 nm en la regeneración ósea del defecto óseo en ratas diabéticas. Se utilizaron seis grupos de 10 ratas Wistar macho y se generó un defecto óseo de 2 mm en las tibias izquierda y derecha de los animales. El animal diabético fue generado con estreptozotocina (40 mg / kg, i.v.). Se compararon las dosis de tratamiento de los defectos óseos con láser de diodo de 50 w - 4 J / cm y 100w - 4 J /. La tibia derecha fue utilizada para el análisis inmunohistoquímico con los marcadores de apoptosis XIAP y Caspasa-3 y la tibia izquierda fue sometida a tomografía computarizada. El marcador caspasa-3 mostró mayor cantidad de apoptosis en todos los grupos no tratados en comparación con ambos tratamientos con láser. No hubo significación estadística para el marcador XIAP. La tomografía computarizada mostró una mejoría del área y el volumen de los defectos óseos en ambos grupos tratados con láser, control y diabéticos. Por lo tanto, la terapia con láser de baja intensidad fue eficaz en la aceleración de la reparación ósea tanto en los grupos control como en los diabéticos. Se evidenció en nuestro estudio que la diabetes afecta negativamente la reparación ósea.

Use of an Alternate Light Source to Detect Tooth and Bone

Resumo O objetivo desse trabalho foi identificar a combinação do comprimento de onda e filtro que melhor detecta dente e osso e verificar qual material biológico (esmalte, raiz dental ou osso) possui maior fluorescência quando exposto a uma fonte de luz alternativa (ALS). Amostras de dente e osso foram iluminadas com uma ALS e fotografadas. Os programas Adobe Photoshop™ e ImageJ™ foram usados para análise das imagens. Os dados obtidos das medidas dos pixels das fotografias foram submetidos a análise de variância. Os valores com efeitos significativos tiveram suas médias comparadas pelo teste de Tukey. Em todos os testes, o nível de significância adotado foi p≤0,05 e os valores calculados pelo sistema SAS. Os resultados mostraram que a melhor combinação para detectar dente e osso é o comprimento de onda 455 nm com o filtro laranja. A fluorescência da raiz é maior que a do esmalte que é maior do que o osso. O material biológico teve maior fluorescência que o material inerte. Esse conhecimento pode auxiliar o perito a triar e detectar esses materiais biológicos, por exemplo em situações em que dentes e pequenos ossos estiverem fragmentados, tanto na cena do crime quanto no laboratório.

Abstract The aim of this study was to identify the combination of wavelength and filter that best detects tooth and bone, and to determine which biological materials (enamel, dental root or bone) have highest fluorescence intensity when exposed to an alternate light source (ALS). Tooth and bone samples were lighted with ALS and photographed. Adobe Photoshop™ and ImageJ™ softwares were used for image analysis. Data obtained by measuring the photograph pixels were subjected to analysis of variance. The mean values of significant effects were compared by the Tukey test. In all tests, the significance level was set at p≤0.05 and the values calculated by the SAS system. The results showed that the best combination for detecting tooth and bone is an illumination wavelength of 455 nm with an orange filter. The fluorescence of dental root is greater than that of enamel, which in turn is greater than that of bone. The biological material had markedly higher fluorescence than the inert material. This knowledge can help the forensic expert to screen and detect biological materials, for example in situations where there are fragmented teeth and small bones, both at the scene and in the laboratory.

Imágenes de fluorescencia de rayos X en huesos humanos y su potencial aplicación in vivo / Images of X-ray fluorescence in human bones and their potential application in vivo

El conocimiento de la concentración y la distribución espacial de los elementos químicos presentes en diferentes órganos y tejidos resulta un parámetro útil para el diagnóstico de determinadas patologías o niveles por sobre los límites tolerables, por lo tanto el conocimiento de los elementos presentes en un tejido vivo, su concentración y distribución espacial podría proporcionar información relevante respecto del estado de salud de un individuo. Se presenta una aplicación de una nueva técnica de fluorescencia rayos X dispersiva en energía mediante barrido, la cual se puede aplicar a muestras de diferente composición y forma, a diferencia de, la mayoría de las técnicas existentes, que son aplicables sólo a muestras planas. Esta técnica permite la obtención de imágenes bidimensionales de los elementos químicos presentes en las muestras de un modo tanto mono como multielemental. En este trabajo es aplicada a un conjunto muestras óseas humanas y tarso y dedos de Gallus gallus (pollo) faenado, obteniéndose una distribución espacial 2D con diferentes niveles de intensidad fluorescente dependiendo del elemento detectado y de su concentración. Las imágenes logradas consideran áreas de hasta104 mm2, con una resolución espacial de hasta 0,25 mm2 y en un tiempo de adquisición de alrededor de 20 min. También se lleva a cabo un cálculo de la dosis de la radiación asociada a este tipo de análisis XRF, encontrándose que los niveles aplicados para la obtención de una imagen XRF son tolerables. Lo anterior permite concluir que sería posible el uso de esta técnica para una aplicación in vivo.

The knowledge of the concentration and spatial distribution that chemical elements present in different organs and tissues is a useful parameter for diagnosis of certain diseases or element levels above limits accepted as healthy. Therefore, development of techniques to identify the chemical elements present in a living tissue and obtaining information about their concentration and spatial distribution might be relevant to determine an individual's health status. This work presents an application of a new X-ray fluorescence technique, energy dispersive by scanning, which can be applied to samples of different composition and shape, unlike most of the existing techniques, only applicable to flat samples. This technique allows the acquisition of two-dimensional images of the chemical elements present in a sample in both mono and multi-elemental mode. In this work the technique is applied to a set of human bone samples and tarsus and fingers of a dead Gallus gallus (chicken), obtaining a 2D spatial distribution with different levels of fluorescence intensity, depending on the detected element and its concentration. The acquired images consider areas up to 104 mm2, with a spatial resolution of 400 mm2 and an acquisition time of about 20 min. Calculations of the radiation dose associated with this type of XRF analysis were also carried out, and the findings show that the levels applied to obtain an XRF image are tolerable. The latter leads to the conclusion that it would be possible to use this technique for an in vivo application.

Avaliação da interface osso-implante em tíbias de coelho irradiadas / Bone-implant interface evaluation in irradiated rabbit tibiae

O câncer de cabeça e pescoço é comumente tratado por combinação de cirurgia e radioterapia. Nesses casos, a reabilitação com próteses implanto-suportadas muito pode contribuir para restabelecimento de estética e função. A radioterapia, entretanto, pode provocar diversos problemas tais como xerostomia, alteração da microbiota oral, aumento da suscetibilidade a processos infecciosos e prejuízo generalizado para o metabolismo dos tecidos envolvidos. A despeito de todas essas alterações, os implantes, em muitos casos, representam a única opção para uma recuperação funcional adequada. Diversas substâncias, tais como o plasma rico em plaquetas (PRP), já foram avaliadas no sentido de melhorar a integração óssea dos implantes, a qual é crítica no osso irradiado. O PRP contém alta concentração de plaquetas e fibrinogênio e pode ser obtido através da centrifugação do sangue coletado do paciente. A proposta do presente trabalho foi realizar um estudo experimental em animais de modo a determinar o quanto a irradiação pode prejudicar a formação da interface osso-implante além de mensurar o quanto a utilização do PRP pode modificar a osteointegração. Foram utilizados 18 coelhos divididos em três grupos: Grupo I, implantes instalados em osso não irradiado; Grupo II, implantes instalados em osso irradiado; Grupo III, implantes instalados em osso irradiado com uso do PRP. Todos os implantes foram instalados em epífise proximal de ambas as tíbias, que foram irradiadas 40 dias antes (1727cGy). Todos os animais foram sacrificados 40 dias após a instalação dos implantes para que fossem obtidas lâminas para análise histomorfométrica ao microscópio. Foram investigadas a extensão do contato osso-implante e a área de osso neoformado entre as espiras. ...

Efecto de la terapia láser de baja intensidad (LLLT) en defectos óseos en ratas / Effect of low level laser treatment (LLLT) in osseous defects created in rats

Objetivo: determinar si la terapia láser favorece la cicatrización del tejido óseo en defectos realizados en cresta tibial de ratas, haciendo evaluaciones a los 7, 14 y 21 días de tratamiento. Material y métodos: treinta ratas Wistar con defectos óseos en cresta tibial se dividieron en 3 grupos de 15 ratas cada uno. El grupo control sin tratamiento y el grupo experimental irradiado con láser AsGaAl con una longitud de onda 835 nm, una energía de 3.5 J, una fluencia de 90 J/cm2, un tiempo de irradiación por aplicación de 120 segundos, a una distancia de 2 mm durante 21 días seguidos. El equipo utilizado fue un AsGaAl marca DMC, modelo WL II unit 2910, con una longitud de onda de 685 nm - rojo visible 830 nm - infrarrojo una potencia de emisión de 35 mw y 100 mw, una tensión de alimentación de 90 v ~ 230 v y una potencia eléctrica de 10 w, fabricado en USA. Una vez fijadas en formol, se recuperaron las tibias libres de tejidos blandos. Se descalcificaron en EDTA, se incluyeron en parafina y se hicieron cortes histológicos que se tiñeron con hematoxilina-eosina. Los preparadosse observaron al microscopio y se midió por triplicado el porcentaje de hueso trabecular formado mediante la utilización del software analizador de imágenes Image Pro Plus. Resultados: A los 7 días el porcentaje de hueso trabecular fue de 43,3 ± 9,5 en el grupo control yde 53,7 ± 9,0 en el grupo láser irradiado (p < 0.05). No se encontraron diferencias significativas ni alos 14 días (62,3 ± 8,9 versus 58,7 ± 10,6%, respectivamente), ni a los 21 días (60,6 ± 12,7% versus 66,3 ± 5,3%, respectivamente). Conclusiones: Estos hallazgos sugieren que la aplicación de láser favorece la cicatrización ósea precozmente (7 días) en ratas con defectos tibiales, a los 14 y 21 días no se registraron efectos inhibitorios ni estimulantes significativos de la osificación.

Effect of radiation on growing long bones of young albino rats

The deleterious effects of radiation have been recognized for a almost century and continue to be seen today, because of improved survival in patients treated for malignancy with radiotherapy with or without other treatments. The present study was designed to evaluate the effect of radiation on the weight and growth of long bones on young Albino rat litters. Anatomy Department, Basic Medical Science Institute, Jinnah Postgraduate Medical Center Karachi. July 2008 to December 2008. 20 litters [10 days age] of Albino rats were divided in two groups. Group A [control], and Group B, was given 5Gy gamma radiation to whole body for 2.02 mm. from 60-unit cobalt chamber. These groups were further divided into 2 sub-groups, each comprising of 5 litters, for 2 weeks and 4 weeks study. Their weight was observed weekly and their CRL, fore limb and hind limb was measured at the end of study. At the end of study, the animals were sacrificed under anesthesia; their long bones were removed and measured with Digital caliper. A significance decrease in the weight of irradiated animals was noted. There was a significant decrease in the measurement of CRL, Forelimb and Hind limb and there was a significant decrease in the length and width of long bones of radiated animals. Total body irradiation causes growth retardation, before epiphyseal plate closure. Irradiation of growing bone typically results in retardation of longitudinal growth

Aplicación de celda fotoacústica diferencial en la determinación de la permeabilidad de agua en hueso descalcificado / Application of differential photoacoustic cell to determine water permeability in decalcified bone

La espectroscopia mediante celda fotoacústica diferencial (CFD) tiene la capacidad de medir in situ el desarrollo de diversos procesos dinámicos, entre otros la difusión de agua a través de una membrana. Mediante esta técnicase realizó el estudio de permeación de agua en huesos de rata Wistar sanos y descalcificados. Los huesos descalcificados fueron tratados mediante estimulación electromagnética a fin de evaluar la actividad celular en el hueso y, en su caso, detener la descalcificación del mismo. En este trabajo fue posible determinar la viabilidad de la CFD para la evaluación de densidad ósea indirectamente, siendo posible efectuar la evaluación in situ de permeación de agua, así como la cantidad de agua retenida en la estructura ósea al finalizar las pruebas en CFD.

Harmful effects of 41 and 202 MHz radiations on some body parts and tissues.

Many types of invisible electromagnetic waves are produced in our atmosphere. When these radiations penetrate our body, electric fields are induced inside the body, resulting in the absorption of power, which is different for different body parts and also depends on the frequency of radiations. Higher power absorption may result into health problems. In this communication, effects of electromagnetic waves (EMW) of 41 and 202 MHz frequencies transmitted by the TV tower have been studied on skin, muscles, bone and fat of human. Using international standards for safe exposure limits of specific absorption rate (SAR), we have found the safe distance from TV transmission towers for two frequencies. It is suggested that transmission towers should be located away from the thickly populated areas and people should keep away from the transmission towers, as they radiate electromagnetic radiations that are harmful to some parts/tissues of body.

Effect of gamma rays on the bone repair process in rats with estrogen deficiency

This study aimed at evaluating the bone repair process in ovariectomized rats submitted to an irradiation procedure. For this purpose, one hundred rats were randomly divided in four experimental groups: control, ovariectomized, irradiated and irradiated/ovariectomized. A bone defect was made on all animals' tibias. Three days after surgery, only irradiated and irradiated/ovariectomized rats received 8 Gy of gamma rays on the lower limbs region. The animals were sacrificed 7, 14, 21 and 28 days after surgery in order to assess the repair process. It was possible to observe a delay in the bone repair process in the irradiated/ovariectomized group, in which there was a remarkable association between estrogen deficiency and ionizing radiation resulting in the reduction of newly formed bone production, thus accelerating the resorption process.

O objetivo deste trabalho foi avaliar o processo de reparo ósseo em ratas ovariectomizadas submetidas ao procedimento de irradiação. Para isto, cem ratas foram aleatoriamente divididas em quatro grupos experimentais: controle, ovariectomizado, irradiado e ovariectomizado/irradiado. Um defeito ósseo foi confeccionado nas tíbias de todos os animais. Três dias após a cirurgia, apenas os animais pertencentes aos grupos irradiado e ovariectomizado/irradiado receberam 8 Gy de radiação gama na região dos membros inferiores. Os animais foram sacrificados 7, 14, 21 e 28 dias após a cirurgia. Foi possível observar um atraso no processo de reparo ósseo nos animais do grupo ovariectomizado/irradiado, no qual houve uma marcante associação entre deficiência de estrógeno e radiação ionizante, resultando na redução da produção de osso neoformado, acelerando o processo de reabsorção.

Microwave-induced fast decalcification of rat bone for electron microscopic analysis: an ultrastructural and cytochemical study

Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4ºC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37ºC. In the first day, the specimens were irradiated 9 times and stored at 40ºC overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.

A preservação da estrutura de ossos é dependente da qualidade e da velocidade em que ocorre o processo de desmineralização. Neste estudo foi observada a ultraestrutura de maxila de rato descalcificada utilizando microondas. Ratos Wistar sofreram perfusão com paraformaldeído e o segmento de maxila retirado e fixado em glutaraldeído. Após esta etapa algumas amostras foram descalcificadas por imersão em solução de Warshawsky durante 45 dias a 4(0)C. Outras amostras foram submetidas a irradiação por microondas (forno de microondas doméstico 700 Watts de potência), durante 20 s/350 W/ ± 37ºC. No primeiro dia foram realizadas um total de 9 irradiações e os espécimes foram deixadas posteriormente a 4ºC por 12 h na solução descalcificadora sem agitação. No segundo dia, os fragmentos foram submetidos à nova irradiação totalizando 20 banhos, trocando-se a solução e o gelo a cada banho. A seguir algumas amostras foram pós-fixadas com tetróxido de ósmio e outras com tetróxido de ósmio e piroantimonato de potássio. As amostras foram observadas em microscópio eletrônico de transmissão. Os resultados mostraram que o processo de descalcificação ativado por microondas reduziu para 48 h o período de descalcificação, o qual pelo método tradicional ocorre em 45 dias.

Effects of low level pulsed radio frequency fields on induced osteoporosis in rat bone.

Effect of modulated pulsed electromagnetic fields (PEMFs; carrier frequency, 14 MHz. modulated at 16 Hz of amplitude 10 V peak to peak) on sciatic neurectomy induced osteoporosis in rat femur and tibia resulted in statistically significant increase in bone mineral density, and deceleration in bone resorption process and consequently further osteoporosis in rat bone. These results suggest that such an effective window of pulsed radio frequency fields may be used therapeutically for the treatment of osteoporosis.

Efeitos da radiaçäo laser de dióxido de carbono em tecido ósseo: estudo macroscópico em ratos / Effect of carbon dioxide laser radiation on osseous tissue: macroscopic study in rats

O laser de dióxido de carbono (CO²), pelas suas propriedades intrínsecas, tem se tornado um instrumento cirúrgico importante; entre estas podemos citar: hemostasia, reduçäo do edema e da dor pós-operatória e esterilizaçäo do campo cirúrgico. Seu uso em tecido ósseo para realizaçäo de osteotomias ainda é questionável, principalmente devido à possibilidade de iatrogenias causadas pelo aumento da temperatura tecidual, bem como destes efeitos na área paraincisional. O propósito deste estudo foi proporcionar a confecçäo de um plano piloto visando analisar macroscopicamente os efeitos da radiaçäo laser de CO² em tíbia de rato a fim de estabelecerem-se parâmetros de segurança quanto a potência. Foram utilizados 12 ratos. Após anestesia, os ossos foram submetidos a radiaçäo com potência de 1, 3 e 5 watts. Os animais foram sacrificados nos tempos imediatamente após, 3, 7 e 14 dias após a irradiaçäo, visando à remoçäo do osso tratado. Os espécimes obtidos foram observados através de lupa estereoscópica com aumentos de 14, 25 e 40 vezes e fotografados para posterior análise. Os resultados permitiram concluir que a potência de 1 watt proporciona uma melhor qualidade de resposta à reparaçäo e que as potências de 3 e 5 watts provocaram o atraso na cronologia de reparo

Effect of radiation on the bone around healed, osseointegrated dental implants

This experimental study was designed to evaluate the bone reaction around endosteal implants after exposure to ionizing radiation, and to compare this reaction in two different types of implants; hydroxyapatite [HA] coated and titanium plasma sprayed implants. For each of twenty-four male white rabbits; the right femur was implanted with titanium plasma sprayed implant while the left side was implanted with HA-coated implant. After a period of 8 weeks during which the implant osseointegrated, the animals were divided randomly and equally [N=12] into 2 groups; control [C] and experimental [E]. In the later group, both femurs were exposed to cobalt 60 units; 200 rad per day, 5 days a week for 5 weeks. Standardized X Ray were taken for each implant, immediately postoperative as well as, 2nd, 4th, 8th and 20th week post-operative. Bone reaction was detected by measuring bone density around implants using gray scale analysis. Bone density in group C increased from 79 +/- 4.85 to 126.2 +/- 3.22 and from 77.8 +/- 3.16 to 135.6 +/- 4.24 for titanium plasma sprayed and HA- coated implants respectively, and in group E from 81.2 +/- 5.11 to 115.6 +/- 5.24 for titanium plasma sprayed implants and 78.4 +/- 3.64 to 124.9 +/- 4.93 for HA-coated implants. All differences were statistically significant [P<0.05] among each group, and statistically insignificant [P>0.29] between both groups. The results of this study suggested that, fractionated irradiation dose of 50 Gy might not induce an apparent deleterious effect on healed osseointegrated dental implants. Moreover, upon exposure to irradiation, HA-coated implants might provide a better bone reaction than titanium plasma sprayed implants

Efeitos do laser CO² na mandíbula de ratos: estudo através da microscopia eletrônica de varredura / Effects of CO² laser irradiation on rat mandibles: study by scanning electron microscopy

A face lateral do corpo da mandíbula de ratos foi irradiada pelo laser CO² com disparos contínuos de 10 watts de potência. Após três meses, o sulco formado pela irradiação apresentou, em uma grande extensão, material fundido com diversas fraturas. Após sete meses, o periósteo neoformado recobriu amplas áreas da incisão, que apresentou ainda material carbonizado. Um ano após a incisão, o periósteo neoformado estava composto por fibras colágenas, que formaram feixes espessos, transversais à incisão, ou malhas regulares, que recobriram a incisão. Ainda nessa fase, resquícios de material carbonizado foram verificados, caracterizando um retardo na regeneração óssea

Efeitos do raio laser CO2 na superfície óssea da mandíbula de recém-nascidos: estudo ao microscópio eletrônico de varredura / Effects of CO2 laser on the jaw bone surface of newborn infant: an electron microscopy study

No presente trabalho descreve-se a açäo do raio laser CO2 em mandíbulas de recém-nascidos humanos com o auxílio da microscopia eletrônica de varredura. Observou-se a formaçäo de um sulco relativamente profundo, bordas bem delimitadas de tecido ósseo adjacente semelhantes àquelas notadas em estruturas dentais