RESUMO
BACKGROUND: Endoscopy has seen a significant development over recent years in various medical fields with its application expanding from the support of minimal invasive surgery to in situ imaging. In this context, the application of endoscopic techniques to assess the quality of the regenerated bone in situ in the drill hole before implant placement is an appealing approach. AIM: The aim of this study was to use short distance support immersion endoscopy (SD-SIE) to compare the quality of regenerated bone in healed postextraction sites, which are grafted with an in situ hardening ß-TCP, against ungrafted sites, before implant placement. This assessment was based on microscopic bone analysis in combination with the blood vessel count. METHOD: 13 spontaneously healed and 13 grafted postextraction sites in 3 men and 6 women, aged 26-83 years, were evaluated using SD-SIE after 4-6 months. SD-SIE was applied in drill holes before implant placement, and videos were taken from representative central buccal areas. The video recordings were analyzed using Image J software for (1) number of blood vessels per area (NBV), (2) relative area of vessels (VA), (3) relative area of mineralized bone (MBA), (4) relative area of unmineralized bone (UMBA), and (5) relative area of bone substitute (BSA). RESULTS: The grafted sites showed more (1) NBV as well as (2) VA (8.6 ± 1.1; 2.03 ± 0.28%) than the ungrafted sites (2.5 ± 0.6; 1.18 ± 0.36%) (independent t-test; p < 0.05); (3) MBA and (4) UMBA were similar to those in the grafted sites (86.3 ± 2.2 %; 13.7 ± 2.2 %) and to the ungrafted sites (89.5 ± 3.7%; 10.5 ± 3.6%) (independent t-test; p > 0.05); and (5) BSA in the grafted sites was 18.2 ± 5.4%. CONCLUSION: SD-SIE is an interesting new approach for in situ assessment of bone quality and blood supply before implant placement. The regenerated bone in ß-TCP grafted extraction sockets showed an increased vascularization compared to ungrafted sites providing a vital support for subsequent implant placement.
Assuntos
Perda do Osso Alveolar/cirurgia , Perda do Osso Alveolar/terapia , Processo Alveolar/cirurgia , Regeneração Óssea/ética , Substitutos Ósseos/administração & dosagem , Fosfatos de Cálcio/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Processo Alveolar/efeitos dos fármacos , Materiais Biocompatíveis/administração & dosagem , Regeneração Óssea/efeitos dos fármacos , Estudos de Casos e Controles , Implantação Dentária Endóssea/métodos , Implantes Dentários , Endoscopia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Extração Dentária/métodosRESUMO
Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue-equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity. Properties of standard Fricke gel dosimeter for high-dose levels are used as a starting point, and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low-dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose-dependency, showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain an adequate dosimeter response for low-dose levels. A suitable composition from among those studied is selected as a good candidate for low-dose-level radiation dosimetry consisting of a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, Xylenol orange, and tridistilled water. Dosimeter samples are prepared in standard vials for in-phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated using typical X-ray tubes for radiology and calibrated Farmer-type ionization chamber is used as reference to measure dose rates inside phantoms at vial locations. Once sensitive material composition is optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. The aim of this work consists of implementing the optimized gel dosimeter to perform direct measurements of absorbed dose in samples irradiated during microcomputed tomography scanning in order to preliminary assess dose levels for further scanning of small animals for further applications in veterinary and paleontology. As a first attempt, dose distributions were measured in water-equivalent phantoms having dimensions comparable to small animals, 100 to 1000 cm3, approximately. According to the obtained results, it is found that the proposed method shows satisfactory reliability and adequate performance for a promising gel dosimetry system.
Assuntos
Imagens de Fantasmas , Radiometria/instrumentação , Radiometria/métodos , Compostos Ferrosos , Humanos , Doses de Radiação , Reprodutibilidade dos Testes , Soluções , Microtomografia por Raio-XRESUMO
El objetivo de este trabajo fue determinar un algoritmo matemático para cuantificar directamente el ángulo de convergencia (AC) en troqueles de preparaciones dentarias. El modelo experimental consistió en preparaciones coronarias simuladas sobre troqueles de yeso, en el cual el AC fue calculado por tres formulas trigonométricas. Las formulas fueron obtenidas de un modelo matemático en el cual la preparación coronaria representa una forma de pirámide truncada, la cual permite una proyección triangular en un plano. Fueron realizadas 60 mediciones in situ sobre las paredes de 15 troqueles. Se obtuvo una imagen de cada troquel usando una cámara digital (Schick® CDR). El AC fue medido usando la herramientas del software (Control). Los datos fueron analizados estadísticamente y se aplicaron test de propagación de errores. Los ángulos calculados con las tres fórmulas matemáticas ([F1], [F2] y [F3]) mostraron un alto nivel de correlación con el grupo control excepto para dos muestras. Dentro de las limitaciones de este estudio podemos concluir que a través de este algoritmo matemático, es posible cuantificar directamente el AC de las preparaciones coronarias en troqueles. Actualmente la evaluación de los AC tanto en preparaciones realizadas por alumnos de pregrado de odontología como por dentistas, se hacen de manera subjetiva. Las tres fórmulas presentadas en el algoritmo tiene una correlación alta para cuantificar el AC en troqueles. La [F3], es la que mas correlación logra en todas las muestras (0,89).
The aim of this study was to determine a mathematical algorithm to directly quantify the convergence angle (AC) dyes tooth preparations. The experimental model system consisted of crown preparations dyes simulated on plaster, which the CA was quantify by three trigonometric formulas. Formulas were obtained from mathematical models representing the crown preparation as a truncated pyramid shape, allowing a triangular projection on the plane. 60 direct measurements were made in situ on the walls of 15 dyes. An image was obtained from each dye using a digital camera (Schick ® CDR). The CA were measured using software tools (Control). The data were statistically analyzed and test data were applied to propagation of errors. The angles calculated with the three math formulas ([F1], [F2] and [F3]) showed a high level of correlation with the control except for two samples. Within the limitations of this study we can conclude that through this mathematical algorithm, it is possible to directly quantify the AC preparation coronary dyes. Currently the evaluation of AC in both preparations made by undergraduate students of dentistry as well as dentists, are made subjectively. The three formulas presented in the algorithm have a high correlation to quantify the AC dyes. The [F3], correlation is the most accomplished in all samples.
Assuntos
Humanos , Algoritmos , Coroas , Processamento de Imagem Assistida por Computador , Implantação Dentária/métodos , Preparo do Dente/métodos , Implantes Dentários , Modelos DentáriosRESUMO
BACKGROUND: In Chile, three Hantavirus seropositive rodent species (O longicaudatus, A olivaceus and A longipilis) are distributed from the Pacific coast to the Andes mountains and represent nearly 90% of the rodents captured in the Xth Region. AIM: To study the seroprevalence of Hantavirus among captured rodent species and its relationship with the appearance of human cases of pulmonary syndrome. MATERIAL AND METHODS: From May 1998 to September 2001, 675 rodents were captured in the region. Serum samples were tested by ELISA for the presence of IgG antibodies against Andes and Sin Nombre virus. Sera from human cases with a suspected Hantavirus infection were analyzed for IgM antibodies against Black Lagoon virus and for IgG antibodies against Andes and Sin Nombre virus. RESULTS: Twenty two of the 675 rodents were seropositive for the virus, 18 O longicaudatus and 4 A longipilis. Regional seroprevalence changed from 2.2% in 1998, 0.0% in 1999, 1.0% in 2000 and up to 7.1% in 2001. A total of 77 positive human cases were studied from 1998 to March 2002. Although there were positive cases in all seasons, data showed a spring-summer seasonal preponderance. A relationship between the flowering of "colihue" bushes and the increased values of rodent abundance, seroprevalence and positive animals was established. CONCLUSIONS: A dispersal movement of O longicaudatus to open habitats close to human outdoor activities during the dry season was confirmed.