RESUMO

A escolha da plataforma protética em implantodontia é fundamental para garantir o sucesso a longo prazo dos procedimentos. Todos os tipos de conexão protética apresentam vantagens e desvantagens, cabendo ao cirurgião-dentista optar pelo o que melhor se adepta ao seu caso. Uma revisão de literatura foi realizada, abrangendo estudos relevantes que compararam essas duas plataformas protéticas em termos de biomecânica e estética. Foram analisadas revisões de literatura e estudos in vitro, sob as palavras-chave "cone morse", "biomechanics", "abuptment". As pesquisas foram feitas nas bases de dados Scielo e PubMed, e os artigos escolhidos deveriam abordar a estabilidade das conexões, a preservação óssea e a estética peri-implantar. Os resultados da revisão demonstram que a plataforma Cone Morse oferece uma interface mais estável, reduz o afrouxamento de parafusos e minimiza a infiltração bacteriana. Com isso, o Cone Morse contribui para a preservação das estruturas ósseas e gengivais ao redor do implante, tornando-se uma escolha valiosa, especialmente em procedimentos de reabilitação estética.

A choice of the prosthetic platform in implant dentistry is fundamental to ensure long-term success of procedures. All types of prosthetic connections have their advantages and disadvantages, and it's up to the dentist to choose what best suits their case. A literature review was conducted, encompassing relevant studies comparing these two prosthetic platforms in terms of biomechanics and aesthetics. Literature reviews and in vitro studies were analyzed using keywords such as "Cone Morse," "biomechanics," and "abutment." The research was conducted on Scielo and PubMed databases, and the selected articles should address connection stability, bone preservation, and peri-implant aesthetics. The review results demonstrate that the Cone Morse platform offers a more stable interface, reduces screw loosening, and minimizes bacterial infiltration. As a result, Cone Morse contributes to the preservation of bone and gingival structures around the implant, making it a valuable choice, especially in aesthetic rehabilitation procedures.

Assuntos

RESUMO

SUMMARY: Underage drinking has become a major public concern having a negative impact on the growth and development of the skeleton. Peak bone mass is attained during adolescence hence the aim of the study was to investigate the effect of acute binge alcohol consumption on trabecular morphometry and tensile strength of the adolescent mandible in the Sprague Dawley (SD) rat. The study comprised of 24 SD rats, aged 7 weeks, placed into either the alcohol-exposed [n=12 (6 males and 6 female)] or pair-fed control group [n=12 (6 male and 6 female)]. The treatment of the groups was as follows; the alcohol exposed group and the pair-fed control were administered a single daily dose of 3 g/kg of 20 % alcohol 3 days a week (alternate days) for 7 days and a caloric equivalent dose of maltose dextrin via oral gavage, respectively. The animals were terminated on day 7 via pentobarbital injection. The mandibles were harvested and scanned using a Nikon XTH 255L 3D-microCT scanner (Nikon Metrology, Leuven, Belgium), and biomechanical tests were done using a Shimadzu universal tensile strength testing machine (China). Following scanning and reconstruction, the trabecular morphometry was assessed using Volume Graphics Studio® software. A 3-point bending test was used to evaluate the tensile strength of the bone. Findings from our study showed changes in some trabecular parameters in the female alcohol-exposed group, while the male groups remained unaffected. No changes in tensile strength were seen when comparing male pair-fed control and alcohol-exposed groups and when comparing female pair-fed control and alcohol-exposed groups. Trabecular and tensile strength differences were observed between the sexes when comparing male pair-fed control and alcohol-exposed groups to female pair-fed control and alcohol-exposed groups. These findings do suggest that acute binge alcohol consumption has detrimental effects on the bone micro-architecture in female alcohol-exposed rats and that differences are seen between the sexes.

El consumo de alcohol entre menores de edad se ha convertido en una importante preocupación pública que tiene un impacto negativo en el crecimiento y desarrollo del esqueleto. La masa ósea máxima se alcanza durante la adolescencia, por lo que el objetivo del estudio fue investigar el efecto del consumo excesivo de alcohol en forma aguda sobre la morfometría trabecular y la resistencia a la tracción de la mandíbula en ratas adolescente Sprague Dawley (SD). El estudio estuvo compuesto por 24 ratas, de 7 semanas de edad, colocadas en el grupo control expuesto al alcohol [n=12 (6 machos y 6 hembras)] y alimentado en parejas [n=12 (6 machos y 6 hembras)]. El tratamiento de los grupos fue el siguiente; al grupo expuesto al alcohol y al control alimentado en parejas se les administró una dosis única diaria de 3 g/kg de alcohol al 20 % 3 días a la semana (días alternos) durante 7 días y una dosis equivalente calórica de maltosa dextrina mediante sonda oral, respectivamente. Los animales fueron sacrificados el día 7 mediante inyección de pentobarbital. Las mandíbulas se recolectaron y se escanearon utilizando un escáner 3D-microCT Nikon XTH 255L (Nikon Metrology, Lovaina, Bélgica), y las pruebas biomecánicas se realizaron utilizando una máquina de prueba de resistencia a la tracción universal Shimadzu (China). Después del escaneo y la reconstrucción, la morfometría trabecular se evaluó utilizando el software Volume Graphics Studio®. Se utilizó una prueba de flexión de 3 puntos para evaluar la resistencia a la tracción del hueso. Los hallazgos de nuestro estudio mostraron cambios en algunos parámetros trabeculares en el grupo de hembras expuestas al alcohol, mientras que los grupos de machos no se vieron afectados. No se observaron cambios en la resistencia a la tracción al comparar los grupos control de machos alimentados en parejas y los grupos expuestos al alcohol y al comparar los grupos control de las hembras alimentadas en parejas y los grupos expuestos al alcohol. Se observaron diferencias trabeculares y de resistencia a la tracción entre los sexos al comparar los grupos control de los machos alimentados en parejas y expuestos al alcohol con los grupos de control de hembras alimentadas en parejas y expuestas al alcohol. Estos hallazgos sugieren que el consumo excesivo de alcohol tiene efectos perjudiciales sobre la microarquitectura ósea en ratas hembras expuestas al alcohol y que se observan diferencias entre los sexos.

Assuntos

RESUMO

BACKGROUND: Micro-osteoperforation is a minimally invasive technique aimed at accelerating tooth movement. The goal of this novel experimental study was to assess tooth movement and stress distribution produced by the force of orthodontic movement on the tooth structure, periodontal ligament, and maxillary bone structure, with and without micro-osteoperforation, using the finite element method. MATERIALS AND METHODS: Cone-beam computed tomography was used to obtain a virtual model of the maxilla and simulate the extraction of right and left first premolars. Three micro-osteoperforations (1.5 x 5 mm) were made in the hemiarch on the distal and mesial surfaces of upper canines, according to the power tip geometry of the Propel device (Propel Orthodontics, Ossining, New York, USA). An isotropic model of the maxilla was fabricated according to the finite element method by insertion of mechanical properties of the tooth structures, with orthodontic force (1.5 N) simulation in the distal movement on the upper canine of a hemiarch. RESULTS: Initial movement was larger when micro-osteoperforations were performed on the dental crown (24%) and on the periodontal ligament (29%). In addition, stress distribution was higher on the bone structure (31%) when micro-osteoperforations were used. CONCLUSIONS: Micro-osteoperforations considerably increased the movement of both the dental crown and periodontal ligament, which highlights their importance in the improvement of orthodontic movement, as well as in stress distribution across the bone structure. Important stress absorption regions were identified within micro-osteoperforations.

Assuntos

RESUMO

Accurate transverse deformation measurements are required for the estimation of the Poisson function and volume ratio. In this study, pure silicone and soft composite specimens were subjected to uniaxial tension, and the digital image correlation method was used to measure longitudinal and in- and out-of-plane transverse stretches. To minimize the effects of measurement errors on parameter estimation, the measured transverse stretches were defined in terms of the longitudinal stretch using a new formulation based on Poisson's ratios and two stretch-dependent parameters. From this formulation, Poisson functions and volume ratio for soft materials under large deformations were obtained. The results showed that pure silicone can be considered isotropic and nearly incompressible under large deformations, as expected. In contrast, Poisson's ratio of silicone reinforced with extensible fabric can exceed classical bounds, including negative value (auxetic behavior). The incompressibility assumption can be employed for describing the stress-stretch curve of pure silicone, while volume ratios are required for soft composites. Data of human skin, aortic wall, and annulus fibrosus from the literature were selected and analyzed. Except for the aortic wall, which can be considered nearly incompressible, the studied soft tissues must be regarded as compressible. All tissues presented anisotropic behavior.

Assuntos

RESUMO

Many voice disorders are linked to imbalanced muscle activity and known to exhibit asymmetric vocal fold vibration. However, the relation between imbalanced muscle activation and asymmetric vocal fold vibration is not well understood. This study introduces an asymmetric triangular body-cover model of the vocal folds, controlled by the activation of bilateral intrinsic laryngeal muscles, to investigate the effects of muscle imbalance on vocal fold oscillation. Various scenarios were considered, encompassing imbalance in individual muscles and muscle pairs, as well as accounting for asymmetry in lumped element parameters. Measurements of amplitude and phase asymmetries were employed to match the oscillatory behavior of two pathological cases: unilateral paralysis and muscle tension dysphonia. The resulting simulations exhibit muscle imbalance consistent with expectations in the composition of these voice disorders, yielding asymmetries exceeding 30% for paralysis and below 5% for dysphonia. This underscores the relevance of muscle imbalance in representing phonatory scenarios and its potential for characterizing asymmetry in vocal fold vibration.

Assuntos

RESUMO

The objective of this study was to evaluate the reliability of Modified Vector Coding in assessing the coordination and coordination variability of the lower limbs and pelvis during running and to determine the Minimal Detectable Change (MDC). Twenty-five healthy runners participated in a biomechanical analysis of treadmill running using a motion capture system. Modified vector coding was applied to assess the three-dimensional coordination among various pelvis and lower limb segmental couplings. Reliability was assessed using the Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM), MDC, and Bland-Altman analysis to ascertain measurement consistency, agreement, and the smallest clinically meaningful change that exceeds measurement error. The test-retest reliability for 33 of 42 segmental couplings analyzed was good to excellent, with ICC values ranging from 0.613 to 0.928 (p <0.05), which substantiates the robustness of modified vector coding in running biomechanics. However, nine couplings, particularly femur-tibia in the sagittal plane during midstance and foot in the frontal plane-tibia in the transverse plane during late stance, exhibited poor to moderate reliability. These findings underscore the need for cautious interpretation due to significant proportional bias (p <0.05). SEM and MDC provided insights into the precision and minimal clinically significant changes for each coupling. The findings confirm the reliability of modified vector coding for biomechanical analysis in running, with most couplings demonstrating consistent high reliability. Nevertheless, specific couplings should be interpreted with caution due to potential measurement errors. The application of MDC highlights the precision of modified vector coding in biomechanical analyses and emphasizes the importance of careful interpretation to improve clinical and research outcomes in running-related injuries.

Assuntos

RESUMO

Loading both lateral and medial compartments is crucial to understanding the effect of muscle fatigue during sidestep cutting. The present study investigated the changes in tibiofemoral contact forces in the medial and lateral compartments and the muscle force contributions during the sidestep-cutting manoeuvre after a handball-specific fatigue protocol. Twenty female handball athletes performed three trials of the sidestep-cutting manoeuvre before (baseline) and after the fatigue protocol. Motion capture and ground reaction forces were measured, and the data were processed in OpenSim. The variables were compared using statistical parametric mapping (SPM), with a significance level of p < 0.05. The results showed a decreased knee flexion angle during fatigue in the early stance phase. In addition, the post-fatigue analysis demonstrated significantly reduced forces in vasti muscles. Similarly, during fatigue, the SPM analysis showed decreased tibiofemoral contact forces in the vertical and anterior directions. Vertical force applied to both medial and lateral condyles demonstrated a significant reduction after the fatigue protocol. These results indicated that forces applied to the tibiofemoral joint were reduced following the fatigue protocol compared to the baseline values. However, no consistent evidence exists that fatigue increases the risk of knee injuries.

Assuntos

RESUMO

To investigate the biomechanical factors associated with patellofemoral pain in children and adolescents. A cross-sectional, population-based study conducted in Brazil from 2019 to 2023, involving students from public schools. Adjusted prevalence ratios and their respective 95% confidence intervals for the outcome in relation to independent variables were calculated for association analysis, adopting a significance level of 5%. Out of the total of 283 students, 152 were female and 182 were aged between 16 and 18 years old. A positive association was observed between the presence of patellofemoral pain and a poor movement quality in both lower limbs (right side: p = 0.04 and left side: p = 0.04) as well as with dynamic valgus of the left lower limb (p < 0.01). Patellofemoral pain in children and adolescents is associated with poor movement quality in the lower limbs and dynamic valgus of the left lower limb. Actions targeting these biomechanical factors may be crucial for early diagnosis and clinical treatment of this disfunction.

Assuntos

RESUMO

INTRODUCTION: Cine-MRI (cine-magnetic resonance imaging) sequences are a key diagnostic tool to visualize anatomical information, allowing experts to localize and determine suspicious pathologies. Nonetheless, such analysis remains subjective and prone to diagnosis errors. OBJECTIVE: To develop a binary and multi-class classification considering various cardiac conditions using a spatiotemporal model that highlights kinematic movements to characterize each disease. MATERIALS AND METHODS: This research focuses on a 3D convolutional representation to characterize cardiac kinematic patterns during the cardiac cycle, which may be associated with pathologies. The kinematic maps are obtained from the apparent velocity maps computed from a dense optical flow strategy. Then, a 3D convolutional scheme learns to differentiate pathologies from kinematic maps. RESULTS: The proposed strategy was validated with respect to the capability to discriminate among myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy, abnormal right ventricle, and normal cardiac sequences. The proposed method achieves an average accuracy of 78.00% and a F1 score of 75.55%. Likewise, the approach achieved 92.31% accuracy for binary classification between pathologies and control cases. CONCLUSION: The proposed method can support the identification of kinematically abnormal patterns associated with a pathological condition. The resultant descriptor, learned from the 3D convolutional net, preserves detailed spatiotemporal correlations and could emerge as possible digital biomarkers of cardiac diseases.

Introducción. Las secuencias del cine-resonancia magnética (cine-MRI, cine magnetic resonance imaging) son una herramienta diagnóstica clave para visualizar la información anatómica que les permite a los expertos localizar y determinar aquellas anomalías que resulten sospechosas. No obstante, este análisis sigue siendo subjetivo y propenso a errores de diagnóstico. Objetivo. Desarrollar una clasificación binaria y multiclase, considerando diferentes condiciones cardiacas, mediante un modelo espaciotemporal que permita resaltar los movimientos cinéticos para caracterizar cada enfermedad. Materiales y métodos. Este estudio se centra en el uso de una representación de convolución 3D para caracterizar los patrones cinéticos durante el ciclo cardiaco que puedan estar asociados con enfermedades. Para ello, se obtienen mapas cinéticos a partir de mapas de velocidad aparente, calculados mediante una estrategia de flujo óptico denso. A continuación, un esquema de convolución 3D "aprende" a diferenciar patologías a partir de mapas cinemáticos. Resultados. La estrategia propuesta se validó según la capacidad de discriminar entre infarto de miocardio, miocardiopatía dilatada, miocardiopatía hipertrófica, ventrículo derecho anormal y un examen normal. El método propuesto alcanza una precisión media del 78,0 % y una puntuación F1 score del 75,55 %. Asimismo, el enfoque alcanzó el 92,31 % de precisión para la clasificación binaria entre enfermedades y casos de control. Conclusiones. El método propuesto es capaz de apoyar la identificación de patrones cinéticos anormales asociados con una condición patológica. El descriptor resultante, aprendido de la red de convolución 3D, conserva correlaciones espaciotemporales detalladas y podría surgir como posible biomarcador digital de enfermedades cardiacas.

Assuntos

RESUMO

BACKGROUND: People with Parkinson's Disease (PwPD) have motor symptoms that directly interfere on dry land walking performance. Despite the shallow water walking is a viable and beneficial physical intervention for PwPD, it lacks information on the comparison of the biomechanical responses of the shallow water walking by PwPD and age paired healthy individuals. RESEARCH QUESTION: Are there differences in the spatiotemporal and angular responses of shallow water walking by older adults with and without Parkinson's disease? METHODS: In this cross-sectional study, ten older adults (9 men/1 women) with Parkinson disease (PwPD group) and ten older adults (3 men/7 women) without Parkinson's disease (Older group) walked in shallow water at self-selected comfortable speed on pool floor in the immersion depths of waist and xiphoid levels. The 2D kinematic data from the sagittal plane was collected to calculate the walking speed, stride length, stride frequency, duty factor, walk ratio, lower limb joints' range of motion and peak angular speed RESULTS: Both groups reduced similarly the walking speed with the immersion depth increase. The speed decrease was achieved by a reducing both the stride frequency and stride length only in the PwPD. The PwPD had lower contact phase than Older in the waist depth, probably due to the reduced risk of fall in water immersion and to attenuate drag force effects. The total range of joint motion was similar between groups, while the peak angular speed of ankle and knee reduced in the deeper depth in both groups. SIGNIFICANCE: The present findings can help professionals of aquatic rehabilitation to choose the best depth for exercise programs, according to the treatment objectives. To our knowledge, this was the first study that analyzed spatiotemporal and angular variables during shallow water walking of PwPD at different depths and compared them with older people without Parkinson's disease.

Assuntos