Orientador: Pedro Duarte Novaes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T06:39:35Z (GMT). No. of bitstreams: 1 Silva_KarlaRovarisda_M.pdf: 5383756 bytes, checksum: f46eb2dfd48068a21c19841f2e4d3581 (MD5) Previous issue date: 2013 / Resumo: Os efeitos adversos da radioterapia sobre os tecidos orais vêm sendo estudados com intuito de, cada vez mais, entender como esta age sobre o organismo, bem como para o desenvolvimento de métodos ou substâncias que visem à minimização dessas sequelas. Dentre os tecidos que estão na área de exposição, está o ligamento periodontal, que se afetado, pode ocasionar a perna dentária que impreterivelmente interfere na qualidade de vida do indivíduo. Este trabalho teve como objetivo avaliar o efeito da radiação ionizante sobre o ligamento periodontal do dente incisivo de rato albinus wistar, por meio da microscopia de polarização e do teste de força. A amostra constituiu-se de 30 ratos albinus wistar machos divididos em dois grupos, o grupo controle (15) e o grupo irradiado (15). O grupo irradiado foi submetido à sessão única de radioterapia com dose de 15Gy e após 14 dias todos os animais foram sacrificados. Um animal de cada grupo foi perdido durante a execução do trabalho. Desta forma, sete animais de cada grupo foram submetidos ao teste de resistência do ligamento periodontal e os sete restantes tiveram a organização do colágeno avaliada através da microscopia de polarização. Os resultados mostraram que ambos os testes apresentaram diferença estatisticamente significante entre os grupos (p<0,001). Através dos coeficientes de correlação de Pearson encontrou-se também uma forte correlação entre os resultados dos testes (resistência/polarização) de cada grupo (controle/irradiado) (R = 0,683; p < 0,001). Portanto, concluiu-se que a radioterapia pode levar à diminuição da resistência à força de intrusão e provocou a desorganização do colágeno no ligamento periodontal / Abstract: The adverse effects of radiotherapy on oral tissues have been studied in order to increasingly understand how it works on the body, as well as for the development of methods and substances aimed at minimizing these sequelae. Among the tissues that are in the exposition area, is the periodontal ligament which, when affected, can lead to tooth loss, that unfailingly interferes with quality of life. This study had as purpose to evaluate the effect of ionizing radiation over the periodontal ligament of the incisive tooth of the albinus wistar rat, trough the polarizing microscope and the strength test. The sample was composed of 30 albinus wistar male rats, separated into two groups, the control group (15) and the irradiated one (15). The irradiated group was subjected to an only session of radiotherapy, with a 15Gy dose, and after 14 days all the animals were sacrificed. One animal in each group was lost during the study's execution. Hence, seven animals of each group were subjected to the periodontal's ligament resistance test, and the seven remaining had their collagen organization evaluated trough the polarizing microscopy. The results showed that both tests exhibited statistically significance difference between the groups (p<0,001). Using the Pearson correlation coefficients a strong correlation was also found between the tests results (resistance/polarizing) of each group (control/irradiated) (R = 0,683; p<0,0001). Thereby, the conclusion was that radiotherapy can lead to a diminished resistance to the intrusion strength and to a disorganization of the periodontal's ligament collagen / Mestrado / Radiologia Odontologica / Mestra em Radiologia Odontológica

Animal models are essential for making the transition from scientific concepts to clinical application. Such models have proven valuable for spinal research. The cervical spine of sheep is often used because there is similar geometry between sheep and human. Although anatomical similarities are important, biomechanical correspondence is imperative to understand the effects of disorders, surgical techniques, and implant designs. Therefore, the purpose of this study was to conduct a comprehensive study of the sheep cervical spine biomechanics, including experimental and finite element analysis. To determine the flexibility of the multilevel spine, ten adult Suffolk sheep C2-C7 spines were tested, undergoing flexion-extension, lateral bending, and axial rotation. In addition to intact multilevel testing, the roles of the stabilizing structures were studied by sequentially destabilizing function spinal units. The sheep spine is highly flexible, especially in lateral bending (±65˚); motion increases with caudal progression. The sheep spine also has a large neutral zone accounting for 50-75% of the total motion. The facets and capsular ligaments play a key role in stabilization, providing the most stability at the C2-C3 level. In addition to flexibility testing, the sheep spinal ligaments underwent tensile testing until failure to determine the material properties. The ligamentum flavum has the largest failure stress and the capsular ligaments have the largest mean failure force. The longitudinal ligaments have the largest failure strain and the lowest failure force. Overall, the C2-C3 ligaments had the highest failure forces as compared to the ligament type at different levels. This corresponds to the stability the ligaments have at the C2-C3 level during flexibility testing. Moreover, a finite element model of the C2-C7 sheep cervical spine was developed and validated to provide additional insight in the sheep biomechanics. The model compared favorably with experimental testing for all loading cases except extension. In general, the model matched the experimental results within one standard deviation for the multilevel motion as well as the motion at each level. Since the sheep is highly flexible and there is a large neutral zone it was difficult to capture the nonlinearity in all loading directions. The model was used to study the effects of fusion at the C3-C4 level. As expected the motion at the fusion was less than one degree, with the non-fused levels accommodating the loss in motion. The motion increased 15-27%, with the largest increase at C6-C7. To obtain the same rotation as the intact model (±2.5 Nm), larger moments were required, increasing to over 5 Nm for flexion and lateral bending and over 3 Nm for extension and axial rotation. The study provides insight into the sheep cervical spine biomechanics. Researchers and scientists should consider the high flexibility and large neutral zone when designing a study that is to correlate to human spines. The model provides additional details such as stresses in the bone and intervertebral disc that can help researchers determine the effects of different surgical techniques and implant designs. Overall, this study provides valuable biomechanical data that can aid designing preclinical animal studies of the sheep.

No description available.

As an exploratory, developmental injury intervention study, this research investigated the efficacy of providing psychological intervention in the form of relaxation and guided imagery to a group of orthopedic patients recovering from major knee surgery. Utilizing a prospective, experimental research design with 30 subjects randomly assigned to either an intervention, placebo, or control group, this study employed physiological as well as psychological outcome measures. Intervention consisted of 10 individual mental practice sessions for intervention group members as an adjunct to physical therapy. Content of these sessions was intentionally designed to facilitate physiotherapy goals. Imagery protocols with which to deliver these standardized sessions were also designed to directly parallel established physical rehabilitation protocols. Placebo group participants were exposed to nonspecific intervention factors of attention and support, while control group members completed their physical therapy as usual. Results of this study revealed that for this sample of anterior cruciate ligament (ACL) orthopedic patients, psychological injury intervention in the form of relaxation and guided imagery contributed to statistically significant better physical and psychological outcomes. Strength and extension improvement, as well as reduction in state, trait, and reinjury anxiety, were superior for the intervention group as compared to placebo and control groups from preintervention (2 weeks postsurgery) to post-intervention (24 weeks postsurgery). Other benefits of the intervention, according to subject self-report, included pain and stress management, empowerment, control of recovery, and overall body wellness . Implications of these research findings are discussed, as well as suggestions offered for subsequent injury intervention research.

The knee is the most complex joint in the human body. It consists of a system of muscle, bone, and ligaments that endures repetitive loading during daily and athletic activities. When this loading is excessive, damage  to the knee occurs leading to a decreased quality of life.The medial collateral ligament (MCL) is one of the 4 major ligaments known to be commonly injured in the knee. The risk of injury to the knee joint increases with the elderly and individuals who experience chronic dehydration. For this reason, the focus of this study is to compare different mechanical quantities that can be used to analyze damage to the MCL. In this study, a novel mechanical testing protocol is used to progressively induce damage in dehydrated rat MCLs by performing tensile tests. This involves stretching the ligaments along their longitudinal axes to consecutive and increasing displacements starting at a 0.4 mm displacement and in increments of 0.2 mm until complete failure occurs. The load and change in length that the ligament experiences are measured at each displacement. Three different methods were evaluated to determine subfailure and damage propagation in rat MCLs: changes in tangent stiffness and chord stiffness, and changes in the load value at the 0.4 mm displacement for each load-displacement curve. The findings of this study indicate that the tangent stiffness and load at the 0.4 mm displacement provide information of the early onset of damage propagation. The decrease in chord stiffness of the ligament does not indicate damage progression in the ligament, but rather is the sign of the imminent failure of the MCL.This study provides insightful data into understanding the subfailure damage in the MCL. / Master of Science

No description available.

No description available.

Little research has been done to validate the biomechanical principles of tibial tuberosity advancement (TTA) throughout stance. The present study evaluates the effects of TTA on kinematics of the cranial cruciate (CrCL) deficient stifle during early, middle, and late stance. Cadaveric pelvic limbs were evaluated for the effects of TTA on kinematics under a load equivalent to 30% bodyweight and under the following treatment conditions: intact CrCL, CrCL deficient, TTA-treated, and TTA treated + meniscal release. Electromagnetic tracking sensors were used to determine tibial subluxation and rotation relative to the femur. Transection of the CrCL resulted in significant cranial tibial subluxation during early, middle, and late stance and significant internal rotation during early and middle stance. TTA normalized tibial subluxation in early, middle, and late stance but was unsuccessful in normalizing axial rotation in middle stance. Meniscal release had no effect on cranial/caudal or rotational displacement when performed following TTA.

Objective: The objective of this work was to characterize the nonlinear anisotropic material constitutive response of the interspinous ligament (ISL). Methods: Cadaveric test samples of the interspinous ligament were tested using the anisotropic small punch test. The measured force-displacement response served as experimental input into a system identification optimization routine to determine the constitutive material parameters that replicated the measured material response. Results: The constitutive behavior of the ISL is notably different from that reported for knee, shoulder, and hip ligaments. Specifically, the high collagen fiber content and unique collagen architecture provided a stiffer material response. The results from the present work were compared with available data from the literature for the ISL and were found to be consistent with reported failure stress and strain to failure. Conclusion: The ISL has unique constitutive properties and architecture that provide mechanical and clinical stability to the lumbar spine during flexion. The characterization data obtained during accomplishment of this thesis provide valuable insights into these roles. The present work provides a first step to fully characterize and understand both physiological and pathological motion of the spine. Further research is necessary to clarify the contributions of spinal ligaments to spine stability and how damage to spinal ligaments may contribute to chronic lower back pain.

The purpose of this project is to quantify the effects of increasing spinal ligament fidelity on the mechanics of the human lumbar spine using finite element analysis (FEA). In support of this goal, a material characterization study was completed to provide anisotropic, nonlinear material parameters for the human anterior longitudinal ligament. (ALL). Cadaveric samples of the human ALL were tested using a punch test technique. Multi- axial force-deformation data were gathered and fit to a commonly used transversely isotropic material model using an FEA system identification routine. The resulting material parameters produced a curve that correlated well with the experimental curve (R2≥0.98). Recently published material data on several major spinal ligaments have been incorporated into an existing finite element model of the human lumbar spine. This data includes the results from the above mentioned material characterization, similar material characterizations of the supraspinous (SSL) and interspinous (ISL) ligaments, localized material properties of the SSL and pre-strain data for the ISL, SSL and ALL. These results have been incorporated both separately and compositely into the finite element model and each configuration has been simulated in spinal flexion, extension, axial rotation and lateral bending. Results suggest that the effects of increased ligament model fidelity on bone strain energy were moderate and the effects on disc pressure were slight, and do not justify a change in modeling strategy for most clinical applications. There were significant effects on the ligament stresses of the ligaments that were directly modified, suggesting that these phenomenon should be included in FE models where ligament stresses are the desired metric.