Research progress on the mechanical compatibility of restorative materials with dental tissue / 口腔疾病防治

@#As the main means of mastication, teeth can withstand countless functional contacts. The mechanical properties of teeth are closely related to their tissue structure. Enamel and dentin have a high hardness and modulus of elasticity, and their graded structure allows them to withstand bite forces without being susceptible to fracture. When tooth tissue is defective, full crown restoration is often needed to restore the normal shape and function of the tooth. Metal materials, ceramic materials, and polyetheretherketone (PEEK) materials are commonly used for crown restoration. Metal materials have certain disadvantages in terms of aesthetics and are relatively rarely used in clinical practice. Ceramic materials with different compositions exhibit differences in performance and aesthetics, but their elastic modulus and hardness are much higher than those of dental tissue, resulting in mismatching mechanical properties. In contrast, the elastic modulus of PEEK is lower than that of tooth tissue and similar to that of bone tissue, but its properties can be improved by fiber reinforcement. Notably, when the mechanical properties of a restoration material and tooth tissue are not fully matched, the interface between them often forms a potential weak link, which ultimately affects the stability and long-term effect of the restoration. This article introduces the mechanical properties and corresponding structural characteristics of enamel and dentin. On this basis, the advantages and limitations of existing restoration materials are analyzed, and the possibility of biomimetic design of full crowns is further explored.

Comportamiento Mecánico de un Premolar Humano Sano Sometido a Fuerzas Funcionales y Disfuncionales en un MEF / Mechanical Behavior of a Healthy Human Premolar Subjected to Functional and Dysfunctional Forces in a FEM

El propósito de este estudio fue analizar el comportamiento mecánico de la estructura dental sana de un primer premolar inferior humano sometido a fuerzas funcionales y disfuncionales en diferentes direcciones. Se buscó comprender, bajo las variables contempladas, las zonas de concentración de esfuerzos que conllevan al daño estructural de sus constituyentes y tejidos adyacentes. Se realizó el modelo 3D de la reconstrucción de un archivo TAC de un primer premolar inferior, que incluyó esmalte, dentina, ligamento periodontal y hueso alveolar considerando tres variables: dirección, magnitud y área de la fuerza aplicada. La dirección fue dirigida en tres vectores (vertical, tangencial y horizontal) bajo cuatro magnitudes, una funcional de 35 N y tres disfuncionales de 170, 310 y 445 N, aplicadas sobre un área de la cara oclusal y/o vestibular del premolar que involucró tres contactos estabilizadores (A, B y C) y dos paradores de cierre. Los resultados obtenidos explican el fenómeno de combinar tres vectores, cuatro magnitudes y un área de aplicación de la fuerza, donde los valores de esfuerzo efectivo equivalente Von Mises muestran valores máximos a partir de los 60 MPa. Los valores de tensión máximos se localizan, bajo la carga horizontal a 170 N y en el proceso masticatorio en la zona cervical, cuando la fuerza pasa del 60 %. Sobre la base de los hallazgos de este estudio, se puede concluir que la reacción de los tejidos a fuerzas funcionales y disfuncionales varía de acuerdo con la magnitud, dirección y área de aplicación de la fuerza. Los valores de tensión resultan ser más altos bajo la aplicación de fuerzas disfuncionales tanto en magnitud como en dirección, produciendo esfuerzos tensiles significativos para la estructura dental y periodontal cervical, mientras que, bajo las cargas funcionales aplicadas en cualquier dirección, no se generan esfuerzos lesivos. Esto supone el reconocimiento del poder de detrimento estructural del diente y periodonto frente al bruxismo céntrico y excéntrico.

SUMMARY: The purpose of this study was to analyze the mechanical behavior of the healthy dental structure of a human mandibular first premolar subjected to functional and dysfunctional forces in different directions. It was sought to understand, under the contemplated variables, the areas of stress concentration that lead to structural damage of its constituents and adjacent tissues. The 3D model of the reconstruction of a CT file of a lower first premolar was made, which included enamel, dentin, periodontal ligament and alveolar bone considering three variables: direction, magnitude and area of the applied force. The direction was directed in three vectors (vertical, tangential and horizontal) under four magnitudes, one functional of 35 N and three dysfunctional of 170, 310 and 445 N, applied to an area of the occlusal and/or buccal face of the premolar that involved three stabilizing contacts (A, B and C) and two closing stops. The results obtained explain the phenomenon of combining three vectors, four magnitudes and an area of force application, where the values of effective equivalent Von Mises stress show maximum values from 60 MPa. The maximum tension values are located under the horizontal load at 170 N and in the masticatory process in the cervical area, when the force exceeds 60%. Based on the findings of this study, it can be concluded that the reaction of tissues to functional and dysfunctional forces varies according to the magnitude, direction, and area of application of the force. The stress values turn out to be higher under the application of dysfunctional forces both in magnitude and in direction, producing significant tensile stresses for the dental and cervical periodontal structure, while under functional loads applied in any direction, no damaging stresses are generated. This supposes the recognition of the power of structural detriment of the tooth and periodontium against centric and eccentric bruxism.

Assessing muscle stiffness using shear wave elastography / 中华物理医学与康复杂志

Objective:To measure the change in Young′s modulus of the biceps brachii during passive stretching and to assess the potential of shear wave elastography (SWE) as an auxiliary quantitative technique for assessing muscle tone.Methods:Forty-nine stroke survivors and 30 healthy subjects were evaluated using the modified Ashworth scale (MAS). According to their MAS scores they were divided into a healthy group, a healthy elbow group, an MAS class-0 group, an MAS class-1 group, an MAS class-1 + group and an MAS class-2 group. During passive extension of the subjects′ elbows, shear wave elastography was used to image the biceps brachii. Six points of the elbow were selected to record the instantaneous Young′s modulus ( EX) and calculate its change during the movement (Δ E). Those data were correlated with the MAS scores and compared among the groups. Results:Persons with higher MAS scores tended to have a higher Young′s modulus of the biceps brachii, and the modulus was likely to increase more with increases in the angle of elbow extension. From half of the range of motion to full extension there were significant differences in EX and Δ E between MAS class-0 and class-1 groups, as well as between the class-0 and class-1 + groups. There were, however, no significant differences between MAS class-1 and MAS class-1 + . Conclusions:MAS scores can usefully predict biceps brachii stiffness during passive elbow flexion. Shear wave elastography can quantify that stiffness and also muscle tone.

Exploratory study on noninvasive evaluation of renal histopathology by ultrasonic shear wave elastography / 中华肾脏病杂志

Objective:To determine a relationship between ultrasound shear wave elastography (SWE) and pathological lessions of renal tissues in children with chronic kidney disease (CKD).Methods:It was a cross-sectional observational study, involving children admitted to the Department of Pediatrics of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January to December 2021 with definite pathological diagnosis through kidney biopsy. The SWE was used to determine the Young's modulus (elastic modulus) of the cortex and medulla of the upper, middle, and lower poles of the kidney. The renal histopathology was classified or graded. The statistical method was used to analyze the relationship between Young's modulus of the inferior polar cortex (YM cor) and medulla (YM med) of the right kidney and renal pathology. Results:The study included 110 children with definite pathological diagnosis through renal biopsy, aged (10.1±3.4) years old (2-17 years old), with 55 males (50.0%). The body mass index was (20.6±2.4) kg/m 2, and mean arterial pressure was (95±24) mmHg. There were 94 patients (85.4%) with CKD stage 1, 8 patients (7.3%) with CKD stage 2, and 8 patients (7.3%) with CKD stage 3. There was no significant difference of YM cor and YM med in the upper and middle poles of the right kidneys, and YM med in the lower poles of right kidneys in CKD patients with different stages (all P>0.05). Both YM cor [(15.75±3.36) kPa] and YM med [(13.50±2.43) kPa] of CKD stage 3 patients were significantly higher than those of CKD stage 1 patients [(12.94±2.45) kPa, (11.88±2.23) kPa](both P<0.05). There was no significant difference of YM cor and YM med in the lower poles of right kidneys between stage 1 and stage 2 CKD patients (both P>0.05). YM cor[(17.93±3.23) kPa] and YM med [(15.50±1.48) kPa] in patients with crescentic glomerulonephritis were higher than those in patients with focal segmental glomerulosclerosis [(12.71±2.42) kPa, (11.57±2.63) kPa] and mesangial proliferative glomerulonephritis [(12.73±2.04) kPa, (11.48±2.10) kPa](all P<0.05). There was no significant difference of YM cor and YM med between focal segmental glomerulosclerosis and mesangial proliferative glomerulonephritis (both P>0.05). YM cor [(16.30±2.63) kPa] and YM med [(15.54±1.59) kPa] of Lee's Ⅳ grade of IgA nephropathy were higher than those of Lee's Ⅲ grade [(13.32±2.70) kPa, (12.57±2.50) kPa](both P<0.05), while the International Study of Kidney Disease in Children grade of purpura nephritis had no significant correlation with YM cor and YM med (both P>0.05). YM cor [(15.41±2.37) kPa] and YM med [(13.82±2.59) kPa] of interstitial fibrosis/tubular atrophy (T1/T2) group of IgA nephropathy mixed with purpura nephritis were significantly higher than those of T0 group's [(12.99±2.40) kPa, (11.79±2.05) kPa] (both P<0.05). Moreover, crescent formation (C1) group had a higher YM cor [(14.21±2.77) kPa] and YM med [(12.80±2.47) kPa] than those in C0 group [(12.73±2.15) kPa, (11.59±1.97) kPa] (both P<0.05), while YM cor and YM med were unrelated to the mesangial hypercellularity (M), endocapillary cellularity (E), segmental sclerosis or adhesion (S) indicators (all P>0.05). In lupus nephritis patients, YM cor ( r=0.744, P=0.035) and YM med ( r=0.728, P=0.009) were favorably linked with the chronic index, but not with the activity index (both P>0.05). Conclusions:Renal interstitial fibrosis/tubular atrophy and crescentic development are connected with YM cor and YM med at the lower pole of the kidney as measured by SWE. SWE can be used to assess the chronic renal lesions in children with CKD in the early and middle stages. It may develop into a new noninvasive way to assess renal pathology.

Value of endoscopic ultrasound elastography versus contrast-enhanced computed tomography in the diagnosis of gastrointestinal stromal tumors / 中国基层医药

Objective:To investigate the clinical value of endoscopic ultrasound elastography versus contrast-enhanced computed tomography in the risk stratification of gastrointestinal stromal tumors (GISTs). Methods:Clinical and imaging data were obtained from 77 patients who were confirmed to have GISTs and underwent endoscopic or surgical treatment at Wenzhou Central Hospital between May 2019 and April 2021. Endoscopic ultrasound elastography based on a five-point scoring system and hypotonic gastrointestinal contrast-enhanced computed tomography were performed for preoperative risk stratification of GISTs. The two techniques were compared in terms of the accuracy of preoperative risk stratification of GISTs. The imaging features of the two techniques were summarized.Results:According to the postoperative pathological results, 13 patients were at high risk, 13 patients were at medium risk, 35 patients were at low risk, and 16 patients were at extremely low risk. These patients were divided into two groups according to postoperative pathological results: a low-risk group (low risk + extremely low risk) and a medium- and high-risk group (high + medium risk). In the low-risk group ( n = 51), 42 patients were identified by endoscopic ultrasound elastography to have low-risk GISTs and were recommended to receive endoscopic treatment, while the rest 9 patients were identified to have medium-risk GISTs. Contrast-enhanced computed tomography findings revealed that 30 patients had low-risk GISTs and were recommended to receive endoscopic treatment, and 21 patients had medium-risk GISTs. In the medium- and high-risk group ( n = 26), 4 patients were identified by endoscopic ultrasound elastography to have low-risk GISTs, and 22 patients had medium- or high-risk GISTs. Contrast-enhanced computed tomography findings revealed that 9 patients were identified to have low-risk GISTs, and 17 patients had medium- or high-risk GISTs. Endoscopic ultrasound elastography yielded an overall diagnostic accuracy of 83.11% (64/77), while contrast-enhanced computed tomography had an overall diagnostic accuracy of 61.04% (47/77). Endoscopic ultrasound elastography outperformed contrast-enhanced computed tomography in accurate risk stratification of GISTs ( χ2 = 4.66, P < 0.05). In terms of predicting high-risk GISTs, endoscopic ultrasound elastography had a sensitivity of 84.62% and a specificity of 82.35%, both were higher than those of contrast-enhanced computed tomography (sensitivity: 65.38%; specificity: 58.82%), but the differences in sensitivity and specificity between the two techniques were not significant (sensitivity: Fisher's exact test P = 0.590, specificity: χ2 = 0.93, P > 0.05). Conclusion:Endoscopic ultrasound elastography appears to have a better overall diagnostic accuracy in the risk stratification of GISTs compared with contrast-enhanced computed tomography. The combined use of these two techniques may offer a better comprehensive understanding of the perilesional structure and organ involvements and distant metastasis than a single technique, thereby providing a reliable reference for the choice of treatment for GISTs.

Adventitial Collagen Cross-Linking by Glutaraldehyde Reinforcing Human Saphenous Vein - Implication for Coronary Artery Bypass Grafting

ABSTRACT Introduction: A weak venous wall is one of the major reasons contributing to vein graft failure after coronary artery bypass grafting (CABG). We investigated whether adventitial collagen cross-linking by glutaraldehyde reinforces venous wall, preserving the endothelium of veins during high-pressure distention. Methods: Human saphenous veins (SVs) were collected from 40 patients undergoing CABG, and adventitia cross-linking was performed with 0.3% glutaraldehyde for five minutes. The cross-linked SVs were accessed by biodegradation assay, immunofluorescent staining, and tensile test. Native SVs and cross-linked SVs from another 20 patients received the 200 mmHg pressure distention for two minutes. Pressure-induced injury of SVs were accessed by immunohistochemistry and electron microscopy. Results: Time to digestion was 97±13 minutes for native SVs and 720±0 minutes for cross-linked SVs (P<0.05). After adventitial cross-linking, the collagen I fibres of the vein remarkably presented with compact and nonporous arrangement. In the high-stretch region (stretch ratio 1.4-1.8), the Young's elastic modulus of stress-stretch ratio curve in cross-linked SVs was larger than that in native SVs (13.88 vs. 5.83, P<0.05). The cross-linked SVs had a lower extent of endothelial denudation without fibre fracture during high-pressure distension than native SVs. Comparing with the non-cross-linked SVs, the percentage of endothelial nitric oxide synthase staining length on the endothelium of cross-linked SVs was significantly preserved after high-pressure distension (85.2% vs. 64.7%, P<0.05). Conclusion: Adventitial collagen cross-linking by glutaraldehyde reinforced venous wall by increasing stiffness and decreasing extensibility of SVs and mitigated the endothelial damage under high-pressure distension.

Fracture Resistance of Endodontically Restored Teeth with Two System Root Post

ABSTRACT: The objective of this study was to determinate the fracture resistance of endodontically treated teeth and restored with two root post systems: i) resin post, ii) fiber post. A total of 60 teeth were freshly extracted, endodontic ally treated and randomly divided in two groups (n= 30/each group) for standardized restoration; Group 1 (Group R): Resin post and resin restoration, Group 2 (Group FP): Fiberglass post and resin restoration. Both groups' samples were mounted in a metallic base at 135º to allow them to be stabilized and held in the universal testing machine by applying a vertical force at cross speed of 1mm/min. Data were recorded in Newtons (N) Previous to test the fracture resistance; all samples were stored in distilled water at 37 ºC for 24 hours. Data were subject to the Saphiro-Wilk test for normality distribution and Student's t test. Significance was considered at 0.05 values. The values of fiber post group showed normal distribution compared to the resin group, demonstrating less variability among the values. The group FP displayed higher fracture resistance (299.77±100 N) than group R (205.57±86.40 N), with significant differences (p= 0.00002). The greatest fracture resistance was recorded for the group having fiber post reinforced and composite cores. It is suggested that fiberglass post restoration is the first option when endodontic treatment requires core restoration.

RESUMEN: El objetivo del estudio fue determinar la resistencia a la fractura de dientes tratados endodónticamente y restaurados con dos sistemas de endopostes radiculares: I) poste de resina, II) poste de fibra. Un total de 60 dientes recién extraídos fueron tratados endodónticamente y divididos al azar en dos grupos (n= 30/ cada grupo) para la restauración estandarizada; Grupo 1 (Grupo R): Pilares de resina y restauración, Grupo 2 (Grupo FP): Pilares de fibra de vidrio y restauración de resina. Las muestras de ambos grupos se montaron en una base metálica a 135º para permitir su estabilización y sujeción en la máquina universal de ensayos aplicando una fuerza vertical a velocidad transversal de 1 mm/min. Los datos se registraron en Newtons (N), para probar la resistencia a la fractura; todas las muestras se almacenaron en agua destilada a 37 ºC durante 24 horas. Los datos se sometieron a la prueba de normalidad de Saphiro-Wilk y la pruebas t de Student. La significancia se consideró con un valor de 0,05. Los valores del grupo de postes de fibra mostraron una distribución normal en comparación con el grupo de resinas, demostrando menor variabilidad entre los valores. El grupo FP mostró mayor resistencia a la fractura (299,77±100 N) que el grupo R (205,57±86,40 N) que el grupo con diferencias significativas (p= 0,00002). La mayor resistencia a la fractura se registró para el grupo que tenía núcleos compuestos y reforzados con postes de fibra. Se sugiere que la restauración posterior de fibra de vidrio es la primera opción cuando el tratamiento de endodoncia requiere una restauración del núcleo.

Eye bank versus surgeon prepared Descemet stripping automated endothelial keratoplasty tissues: Influence on adhesion force in a pilot study

Purpose: To evaluate and compare the biomechanical properties of the eye bank?prepared and surgeon prepared Descemet stripping automated endothelial keratoplasty (DSAEK) tissues. Methods: In this laboratory study, corneal tissues for research were randomly allocated in the following groups: a) surgeon?cut DSAEK and b) eye bank?prepared (pre?cut and pre?loaded) DSAEK. Endothelial cell loss (ECL), immunostaining for tight junction protein ZO?1, elastic modulus, and adhesion force were investigated. Results: ECL was not found to be significantly different between surgeon?cut DSAEK (7.8% ±6.5%), pre?cut DSAEK (8.6% ±2.3%), and pre?loaded DSAEK (11.1% ±4.8%) (P = 0.5910). ZO?1 was expressed equally across all groups. Surgeon?cut DSAEK grafts showed a significantly higher elastic modulus compared to pre?cut and pre?loaded DSAEK groups (P = 0.0047 and P < 0.0001, respectively). Adhesion force was significantly greater in the surgeon?cut DSAEK compared to pre?cut (P < 0.0001) or pre?loaded DSAEK groups (P = 0.0101). Conclusion: The laboratory data on the biomechanics of DSAEK grafts suggests that surgeon?cut DSAEK grafts present higher elastic modulus and adhesion force compared to eye bank?prepared DSAEK grafts.

Finite Element Analysis and Clinical Research Progress of Tympanic Membrane Perforation and Tympanic Membrane Repair Materials / 医用生物力学

Tympanic membrane perforation is one of the common diseases in otolaryngology. The main causes of tympanic membrane perforation are otitis,trauma and etc. With the rapid development of finite element analysis method, this method is applied to clinical evaluation of tympanic membrane perforation and repair materials. By establishing the finite element model of the middle ear, the characteristics of tympanic membrane perforation and tympanic membrane repair materials were analyzed from the biomechanical aspect, with combination of clinical application results. In this review, the finite element analysis and clinic research progress of tympanic menbrane perforation and tympanic membrane repair materials were summarized.

The clinical application study of multimodal ultrasound on the quantitative measurement of muscle mass and hardness in sarcopenia patients / 中华老年医学杂志

Objective:To evaluate the clinical value of musculoskeletal ultrasound in the diagnosis of sarcopenia by measuring the muscle mass and hardness of medial head of gastrocnemius.Methods:According to the diagnostic criteria of Asian Working Group for Sarcopenia(AWGS), 60 patients with sarcopenia were selected as the case group and 24 normal elderly people with matched age as the control group.Two dimensional gray-scale ultrasound was used to measure the muscle thickness, pinnate angle and fascicle length of the right gastrocnemius muscle, and the shear wave elastography was used to measure the Young's modulus(the dynamic stiffness)of the muscle in the states of relaxation and contraction, respectively.The differences of various ultrasound parameters between the two groups were compared, and the relativity of muscle thickness of the medial head of the right gastrocnemius muscle, the feather horn, fascicle length in the case group with sarcopenia was analyzed.The value of the ultrasound measurements in predicting sarcopenia was analyzed by ROC curve.Results:The muscle thickness(10.0±2.1)mm, pinnate angle(16.9±3.2)°, fascicle length(30.5±3.2)mm and Young's modulus[(11.5±2.2)kPa in relaxation state, (23.2±4.0)kPa in contraction state]of the right gastrocnemius muscle were lower in the sarcopenia group than in the control group with matched age[(14.8±1.2)mm, (21.7±2.5)°, (34.2±1.6)mm, (15.0±1.5)kPa, (30.6±2.8)kPa, respectively, t=10.454, 3.612, 5.631, 6.922, 8.173, all P<0.05]. The Young's modulus value was lower in relaxed state than in the contraction state.Pearson correlation analyses showed the muscle thickness and Young modulus were negatively correlated with the age( r=-0.307, -0.285, P<0.05), and the muscle thickness was positively correlated with the limb skeletal muscle mass index( r=0.838, 0.761, P<0.01). Logistic regression analysis showed the muscle thickness and Young's modulus were significantly correlated with sarcopenia( OR=4.576, 3.867). ROC analysis revealed that the threshold values of ultrasound examination of the right gastrocnemius muscle medial head for diagnosis of sarcopenia were as follows: muscle thickness of 11 mm, pinnate angle of 17 degrees, fascicle length of 32 mm, Young modulus at the relaxation state of 12.4 kPa.The sensitivity and specificity of muscle thickness for diagnosis of sarcopenia were the best(86.7% and 100%, respectively)as compared with other measurements. Conclusions:The measurement of muscle mass and muscle hardness of the medial head of gastrocnemius by ultrasound can reflect the decrease of muscle mass and muscle hardness quantitatively, and provide imaging indicators for the prediction of sarcopenia.

A preliminary study of ultrasound shear-wave elastography in evaluation of lumbar multifidus stiffness in healthy adults / 中华超声影像学杂志

Objective:To explore the repeatability of ultrasound shear wave elastography (SWE) in evaluating the Young′s modulus (E) of the lumbar multifidus (LM) and the difference in E of the bilateral LM, and to analyze the E′s change ratio of LM and its impact factors at upright and 90° forward bend positions.Methods:A total of 60 healthy volunteers, selected from interns, standardized training residents and refresher doctors in department of diagnostic ultrasound of Sir Run Run Shaw Hospital of Zhejiang University School of Medicine from July to December in 2020, were examined twice by SWE to estimate the E value of LM at prone, upright and 90° flexion positions, respectively. Firstly, the intraclass correlation coefficient (ICC) was applied to test the reliability between the two repeated measurements.Secondly, the differences in E of the bilateral LM were discussed. The discrepancies in the E value of male and female volunteers at prone, upright and 90° flexion positions and the change ratio of the E value at upright and 90° forward bend positions were also discussed, respectively. Finally, Spearman correlation coefficient was utilized to evaluate the correlations of E and its change ratio with gender, age, BMI and activity level at upright and 90° forward bend positions, respectively.Results:The ICC value in LM measured by SWE was in the range of 0.691 to 0.951. No obvious change in bilateral E values of the same posture was observed for an individual(all P>0.05). The change ratios of E at upright and 90° flexion positions were approximate to 2 and 7, respectively. Moreover, at prone position, the E value exhibited negative correlation with age and activity level of self-assessment ( rs=-0.300, P=0.020; rs=-0.383, P=0.002). The E in female was higher compared with that in male. At active states the change ratio in E was positively correlated with age and activity level ( rs=0.278, P=0.031; rs=0.495, P<0.001), and the E′s change ratio in male was higher than that in female. Conclusions:SWE possesses excellent repeatability in evaluating the E value of LM with no significant difference in E of bilateral LM. The E′s change ratio in LM varies with different contraction strategies and changes with age, sex and self-reported activity level.

Electroacupuncture on motor function in patients with primary osteoporosis: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the effect of electroacupuncture on motor function and muscle state in patients with primary osteoporosis (POP).@*METHODS@#A total of 60 female patients with POP were randomized into an observation group (30 cases, 1 case dropped off) and a control group (30 cases, 1 case dropped off). On the basis of adjusting lifestyle, caltrate was given orally in the control group, 2 pills a day for 4 weeks. On the basis of the treatment in the control group, electroacupuncture was applied at Zusanli (ST 36), Yanglingquan (GB 34), Ganshu (BL 18), Pishu (BL 20), Shenshu (BL 23), etc. in the observation group, with disperse-dense wave of 2 Hz/10 Hz in frequency, once every other day, 3 times a week for 4 weeks. The time of timed up-and-go test (TUGT) and the value of 10 m maximal walking speed (10 m MWS) before and after treatment were compared in the two groups, and the Young's modulus values of bilateral multifidus muscles in prone position and sitting position before and after treatment were compared by real-time shear wave elastography (SWE) in the two groups.@*RESULTS@#After treatment, the TUGT time was decreased compared before treatment in the observation group (P<0.01), and that in the observation group was shorter than the control group (P<0.01). After treatment, the value of 10 m MWS test was increased compared before treatment in the observation group (P<0.05). After treatment, the Young's modulus values of bilateral multifidus muscles in prone position and sitting position were increased compared before treatment in the observation group (P<0.01); except for the left side in sitting position, the Young's modulus values of multifidus muscles in the observation group were higher than those in the control group (P<0.01, P<0.05).@*CONCLUSION@#On the basis of oral caltrate, electroacupuncture can improve the motor function and muscle state in patients with POP.

Effect of antioxidant agents after dental bleaching on luting of ceramic laminates / Efeito de agentes antioxidantes pós-clareamento na cimentação de laminados cerâmicos

O objetivo deste estudo in vitro foi avaliar o efeito da aplicação de agentes antioxidantes após o clareamento dentário e previamente à cimentação de laminados cerâmicos na estabilidade cromática do conjunto restaurador, assim como nas propriedades mecânicas de nanodureza (HIT), módulo de elasticidade (Eit*), grau de conversão, resistência de união e morfologia da interface adesiva. Ademais, a neutralização de peróxido de hidrogênio e a caracterização superficial do esmalte, como ângulo de contato, energia de superfície, energia livre total de interação, microscopia eletrônica de varredura e espectroscopia de energia dispersiva do substrato submetido à ação das soluções antioxidantes e do agente clareador também foram analisados. Duzentos e quarenta e dois blocos de esmalte dentário (7x8x0,6mm) foram utilizados para o processo de cimentação e distribuídos em grupos experimentais de acordo com os métodos de procedimentos (grupo não clareado, grupo clareado com Whiteness HP Maxx 35%), tipos de antioxidantes adotados (controle; ácido ascórbico 10% e α-tocoferol 10%) e períodos de cimentação (após 24 horas e 14 dias do processo de cimentação) (n = 22). Foi utilizado o sistema adesivo Tetric N Bond Universal e o cimento resinoso Variolink Esthetic LC (Ivoclar Vivadent) como agentes cimentantes. Os dados foram submetidos a testes estatísticos de normalidade e analisados por ANOVA e teste de Tukey (α = 0,05). Os dados da morfologia da interface adesiva, obtidas pela microscopia confocal a laser, foram submetidas ao teste Kappa inter-examinadores e os dados foram submetidos aos testes Kruskal-Wallis e Dunn (α = 0,05). Os resultados mostraram que, de modo geral, a utilização da solução antioxidante α-tocoferol 10% pós-clareamento no período mediato promoveu resultados satisfatórios com relação à estabilidade cromática do conjunto restaurador, assim como para as propriedades mecânicas, grau de conversão, resistência de união e morfologia da interface adesiva comparado ao grupo clareado sem associação dos agentes antioxidantes, tanto para o período mediato, quanto para o período de 14 dias (p< 0,05). A solução de αtocoferol 10% apresentou maiores valores de neutralização do peróxido de hidrogênio e maiores valores de molhabilidade do esmalte em relação aos grupos controle e ácido ascórbico (p< 0,05). A energia de superfície e energia livre total de interação do esmalte dentário foi significativamente influenciada pelo tratamento clareador (p< 0,05). Dessa forma, conclui-se que o emprego da solução antioxidante α-tocoferol 10% promoveu resultados promissores, sugerindo que o mesmo poderia ser utilizado mediatamente após o clareamento dental na cimentação de laminados cerâmicos(AU)

The aim of this in vitro study was to evaluate the effect of antioxidant agents application after tooth bleaching and prior to luting of ceramic veneers on color stability of the restorative set, as well as on mechanical properties of nanohardness (HIT), elastic modulus (Eit*), degree of conversion, bond strength and morphology of the adhesive interface. Furthermore, the hydrogen peroxide neutralization and surface characterization of enamel, such as contact angle, surface energy, total free energy of interaction, scanning electron microscopy and energy-dispersive spectroscopy of the substrate submitted to the action of antioxidant solutions and bleaching agent were also analyzed. Two hundred forty two dental enamel blocks (7 x 8 x 0.6 mm) were used for the luting process and distributed into experimental groups according to the procedure methods (unbleached group, bleached group with Whiteness HP Maxx 35%), types of antioxidants adopted (control; 10% ascorbic acid and 10% α-tocopherol) and the luting periods (24 hours and 14 days after the luting process) (n = 22). Tetric N Bond Universal adhesive system and Variolink Esthetic LC resin cement (Ivoclar Vivadent) were used as luting agents. Data were submitted to statistical tests of normality and analyzed by ANOVA and Tukey tests (α = 0.05). The adhesive interface morphology data, obtained by confocal laser microscopy, were submitted to the interexaminer Kappa test and the data were submitted to Kruskal-Wallis and Dunn´s tests (α = 0.05). The results showed that, in general, the use of 10% α-tocopherol antioxidant solution after bleaching in mediate period promoted satisfactory results regarding the color stability of the restorative set, as well as for the mechanical properties, degree of conversion, shear bond strength and adhesive interface morphology compared to the bleached group without antioxidant agents association, both for the mediate and 14-day period (P < 0.05). The 10% αtocopherol solution showed higher hydrogen peroxide neutralization values and higher enamel wettability values compared to the control and ascorbic acid groups (P < 0.05). Surface energy and total free energy of interaction of tooth enamel were significantly influenced by the bleaching treatment (P < 0.05). Thus, it is concluded that the use of 10% αtocopherol antioxidant solution promoted promising results, suggesting that it could be used mediately after tooth bleaching on luting of ceramic laminates(AU)

Effects of dynamic pressure on the proliferation and mechanical properties of rabbit adipose mesenchymal stem cells transfected with insulin-like growth factor-1 / 中国组织工程研究

BACKGROUND: Adipose mesenchymal stem cells are currently recognized as excellent seed cells for tissue engineering cartilage. Gene transfection technology can effectively induce them to differentiate into cartilage. The bioreactor is used to simulate the mechanical environment in vivo. It is a new idea for the majority of scholars to explore the construction of tissue engineering cartilage in vitro. OBJECTIVE: To investigate the effects of cyclic dynamic compressive stress combined with insulin-like growth factor-1 gene transfection on the proliferation and elastic modulus of rabbit adipose mesenchymal stem cells implanted in chitosan/gelatin scaffold. METHODS: Rabbit adipose mesenchymal stem cells were transfected with pcDNA3.1-IGF-1 gene mediated by liposome. The stable transfected cell lines were screened by G418. The adipose mesenchymal stem cells transfected with or without insulin-like growth factor-1 gene were inoculated in chitosan/ gelatin scaffold at the density of 5×1010 L-1 for 2 days, and cultured under dynamic pressure (2% at 1 Hz, 4 hours per day) or static culture conditions for 7 days, respectively. The morphological changes of the cell/scaffold complex were observed by scanning electron microscope, Masson trichrome staining and alcian blue staining. The cell proliferation curve was drawn by MTT assay. The cell proliferation efficiency and distribution were evaluated by CM-Dil fluorescence-labeling method, and the content of total glycosaminoglycan was quantitatively determined by DMMB. The differences of type II collagen among different groups were compared with real time PCR. Compressive mechanical properties of the cell/scaffold constructs were assessed using a BioDynamic™ mechanical tester, and the corresponding elastic modulus was calculated. RESULTS AND CONCLUSION: Dynamic pressure combined with insulin-like growth factor-1 transfection could significantly improve the cell proliferation ability of the cell/scaffold complex; the cell distribution was more uniform; glycosaminoglycan and collagen secretion in the cartilage-specific extracellular matrix were increased; the expression levels of type II collagen were up-regulated; and the mechanical properties were significantly improved. The cell proliferation and elastic modulus of insulin-like growth factor-1 group were better than those of single pressure group, but the distribution of cells in scaffolds was more uniform under dynamic pressure. The results indicate that both dynamic pressure and insulin-like growth factor-1 gene transfection can significantly improve the proliferation and mechanical properties of rabbit adipose mesenchymal stem cells; the two have synergistic effect.

Preparation and characterization of dissolving microneedles with nano-enhanced mechanical properties / 药学学报

In this paper, the effects of the blend of nanoparticles and microneedle matrix materials on the mechanical properties of dissolving microneedles were studied mainly, so as to construct microneedles with excellent mechanical properties. Different kinds of nanoparticles (calcium carbonate, hydroxyapatite, silica), particle sizes (20, 60, 100 nm) and the proportion of prescription (2%, 6%, 10%) were blended with the matrix material [polyvinyl pyrrolidone (PVP), poly(1-vinylpyrrolidone-co-vinyl acetate)(PVP/VA)] to form dissolving microneedles. The effects of nanoparticles on the elastic modulus and hardness of the microneedles were investigated using a nanoindenter. The results showed that the elastic modulus and hardness of PVP microneedles were significantly improved by nano-calcium carbonate (P < 0.001), and the elastic modulus and hardness of PVP/VA microneedles were significantly improved by nano-hydroxyapatite (P < 0.001). When the particle size of hydroxyapatite was 20 nm, the elastic modulus of PVP/VA microneedles was (10.6 ± 1.0) GPa, and the hardness was (0.47 ± 0.06) GPa. As the size of the nanoparticles increases, the mechanical performance of the microneedles decreases. When the mass proportion of nano-hydroxyapatite increased from 2% to 6%, the elastic modulus and hardness of the microneedles were significantly improved (P < 0.001), but the effect of continue increasing the proportion of nanoparticles on the microneedles was not significant. The nano-enhanced PVP/VA dissolving microneedles has no irritant effect on intact skin and has a slight irritation to damaged skin, but they disappear completely after 72 h. Animal experiments have been approved by the Laboratory Animal Welfare and Ethics Committee of Zhejiang University of Technology. Therefore, the nano-enhanced dissolving microneedles has good biological safety. To sum up, it is necessary to select the appropriate kind of nanoparticle, particle size, and prescription ratio when microneedles constructing with a given matrix material, so as to effectively improve its mechanical performance.

Prediction Method of Elastic Modulus of Trabecular Bone Based on SE-DenseVoxNet / 中国医疗器械杂志

Osteoporosis is one of the common metabolic diseases, which can easily lead to osteoporotic fractures. Accurate prediction of bone biomechanical properties is of great significance for the early prevention and diagnosis of osteoporosis. Bone mineral density measurement is currently used clinically as the gold standard for assessing bone strength and diagnosing osteoporosis, but studies have shown that bone mineral density can only explain 60% to 70% of bone strength changes, and trabecular bone microstructure is an important factor affecting bone strength. In order to establish the connection between trabecular bone microstructure and bone strength, this paper proposes a prediction method of trabecular bone modulus based on SE-DenseVoxNet. This method takes three-dimensional binary images of trabecular bone as input and predicts its elastic modulus in the z-axis direction. Experiments show that the error and bias between the predicted value of the method and the true value of the sample are small and have good consistency.

Effect of Dietary Challenges on the Flexural Properties of Resin-based Composites

@#This study aims to compare flexural strength and flexural modulus of different resin-based composites (RBCs) and to determine the impact of dietary solvents on flexural properties. Forty specimens (12x2x2mm) for each of two conventional (Aura Easy [AE]; Harmonize [HN]) and one bulk fill (Sonic Fill 2 [SF2]) were fabricated using customised plastic moulds. Specimens were light-cured, measured and randomly divided into four groups. The groups (n=10) were conditioned for 7 days at 37°C: in one of media: air (control), artificial saliva (SAGF), 0.02N citric acid and 50% ethanol–water solution. After conditioning, the specimens subjected to flexural testing. Two-way ANOVA and one-way ANOVA (post hoc: Tukey’s or Dunnett T3 tests) were used at =0.05. Significant differences in flexural properties were observed between materials and conditioning media. Flexural strength and modulus values ranged from 124.85MPa to 51.25MPa; and 6.76GPa to 4.03GPa, respectively. The highest flexural properties were obtained with conditioning in air. Exposure to aqueous solutions generally reduced flexural properties. In conclusion, the effect of dietary solvents on flexural properties were material and medium dependent. For functional longevity of restorations, patients’ alcohol intake should be considered during material selection. Dietary advice (reduce alcohol consumption) should be given to patients post operatively.

Mechanical Properties of Calcification from Human Aortic Valve / 医用生物力学

Objective To measure mechanical properties of calcified tissues from human aortic valve by nanoindentation test. Methods Leaflets from 5 patients with aortic stenosis were collected. Elastic modulus and hardness of the calcified leaflets were obtained by nanoindentationtest. Results The elastic modulus and hardness of the calcified leaflets were (15.69±3.89) GPa and (0.59±0.15) GPa, respectively. Conclusions The elastic modulus and hardness of the calcified valve tissues can be obtained by nanoindentationtest, which provides experimental data for biomechanical research of the valve.

Effects of Liquid Medium Environment on Elastic Modulus of Breast Cancer Cells / 医用生物力学

Objective To study the effect of three kinds of commonly used liquid culture media for in vitro cell experiments on elastic modulus of breast cancer cells, so as to provide references for developing novel diagnosis and treatment approach of tumour based on mechanics principles. Methods The elastic modulus and adhesion force of breast cancer cells MCF7 to atomic force microscopy (AFM) probes in phosphate buffered solution(PBS), Dulbecco’s modified eagle media (DMEM) and DMEM+10% fetal bovine serum (FBS) were measured using AFM technology. Results The elastic moduli of breast cancer cells in PBS, DMEM and DMEM+10% FBS were 2.59, 2.11 and 1.59 kPa, respectively. The cell adhesion forces in the above three kinds of liquid medium environment were 63.81, 66.09 and 121.97 pN, respectively. Cell adhesion force in DMEM+10%FBS was significantly different from that of the other two kinds of liquid media. Conclusions There are significant differences in elastic modulus of breast cancer cells in three kinds of liquid media. The difference between DMEM and DMEM+10%FBS might be caused by the different adhesion force caused by serum proteins in the media, and the difference between DMEM and PBS might be attributed to the difference in pH of the media.

Design of Three-Dimensional Printed Diabetic Insoles with Gradient Modulus / 医用生物力学

Objective To propose a quick and low-cost personalized diabetic foot modeling and insole design scheme, so as to reduce the plantar pressure accurately. Methods The foot model of the patient was constructed by scaling the model with foot feature parameters, to make biomechanical analysis on plantar pressure. By means of numerical mapping model of insole elasticity and plantar pressure, the three-dimensional (3D) personalized insole model with gradient modulus was constructed. The insole was then manufactured via 3D printing technology and used for experimental validation. Results The related mechanical parameters from finite element prediction of the foot model constructed by the scaling modeling method were close to those of the CT reconstructed model, and the maximum error was controlled within 15%. Compared with wearing the normal insole, the peak pressure of the personalized insole was effectively reduced by 20%. The time and economic cost of this simplified design was reduced by approximately 90%. Conclusions The design scheme of the diabetes insole shortens the design cycle, and the personalized insole can effectively and accurately reduce the sole pressure, and reduce the risk of foot ulcer, which provides a technical basis for the promotion of the personalized diabetes insole.