scholarly journals A Comparison of Biomechanical Properties of Implant-Retained Overdenture Based on Precision Attachment Type

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2598
Author(s):  
Małgorzata Idzior-Haufa ◽  
Agnieszka A. Pilarska ◽  
Wiesław Hędzelek ◽  
Piotr Boniecki ◽  
Krzysztof Pilarski ◽  
...  
Keyword(s):  
Distal Part ◽  
Biomechanical Properties ◽  
Central Incisor ◽  
Element Analysis ◽  
Edentulous Mandible ◽  
The Matrix ◽  
Fea Analysis ◽  
Small Deformations ◽  
Made In

This paper aims to compare, in vitro, the biomechanical properties of an overdenture retained by two bar-retained implants and an overdenture retained by two bar-retained implants with ball attachments. An edentulous mandible model was prepared for the study based on the FRASACO mold with two implants. In the first system, the “rider” type (PRECI-HORIX, CEKA) retention structure and the complete mandibular denture with the matrix were made. In the second system, the “rider” type retention suprastructure was also used. In the distal part, (CEKA) clips were placed symmetrically, and a complete mandibular denture, together with the matrix on the bar, and the clip patrices were made. A numerical model was developed for each system where all elements were positioned and related to geometric relations, as in reality. The FEA analysis (finite element analysis) was carried out for seven types of loads: with vertical forces of 20, 50, and 100 N and oblique forces of 20 and 50 N acting on individual teeth of the denture, namely central incisor, canine, and first molar. Displacements, stresses, and deformations within the systems were investigated. Maximum denture displacement in the first system was 0.7 mm. Maximum bar stress amounted to 27.528 MPa, and implant stress to 23.16 MPa. Maximum denture displacement in the second system was 0.6 mm. Maximum bar stress amounted to 578.6 MPa, that of clips was 136.99 MPa, and that of implants was 51.418 MPa. Clips cause smaller displacement of the overdenture when it is loaded but generate higher stress within the precision elements and implants compared to a denture retained only by a bar. Regardless of the shape of the precision element, small deformations occur that mainly affect the mucosa and the matrix.

scholarly journals Molecular and Biomechanical Adaptations to Mechanical Stretch in Cultured Myotubes

2021 ◽  
Vol 12 ◽  
Author(s):  
Dapeng Ren ◽  
Jing Song ◽  
Ran Liu ◽  
Xuemin Zeng ◽  
Xiao Yan ◽  
...  
Keyword(s):  
Mechanical Stretch ◽  
Biomechanical Properties ◽  
Structural Element ◽  
The Past ◽  
Future Challenges ◽  
Cultured Myotubes ◽  
Myotube Hypertrophy ◽  
And Oxidative Stress ◽  
Made In

Myotubes are mature muscle cells that form the basic structural element of skeletal muscle. When stretching skeletal muscles, myotubes are subjected to passive tension as well. This lead to alterations in myotube cytophysiology, which could be related with muscular biomechanics. During the past decades, much progresses have been made in exploring biomechanical properties of myotubes in vitro. In this review, we integrated the studies focusing on cultured myotubes being mechanically stretched, and classified these studies into several categories: amino acid and glucose uptake, protein turnover, myotube hypertrophy and atrophy, maturation, alignment, secretion of cytokines, cytoskeleton adaption, myotube damage, ion channel activation, and oxidative stress in myotubes. These biomechanical adaptions do not occur independently, but interconnect with each other as part of the systematic mechanoresponse of myotubes. The purpose of this review is to broaden our comprehensions of stretch-induced muscular alterations in cellular and molecular scales, and to point out future challenges and directions in investigating myotube biomechanical manifestations.

scholarly journals Anthocyanins as Antidiabetic Agents—In Vitro and In Silico Approaches of Preventive and Therapeutic Effects

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3813 ◽  
Author(s):  
Hélder Oliveira ◽  
Ana Fernandes ◽  
Natércia F. Brás ◽  
Nuno Mateus ◽  
Victor de Freitas ◽  
...  
Keyword(s):  
In Silico ◽  
Functional Foods ◽  
Therapeutic Strategies ◽  
Therapeutic Effects ◽  
Metabolizing Enzymes ◽  
The Past ◽  
The Matrix ◽  
Made In

Many efforts have been made in the past two decades into the search for novel natural and less-toxic anti-diabetic agents. Some clinical trials have assigned this ability to anthocyanins, although different factors like the food source, the amount ingested, the matrix effect and the time of consumption (before or after a meal) seem to result in contradictory conclusions. The possible mechanisms involved in these preventive or therapeutic effects will be discussed—giving emphasis to the latest in vitro and in silico approaches. Therapeutic strategies to counteract metabolic alterations related to hyperglycemia and Type 2 Diabetes Mellitus (T2DM) may include: (a) Inhibition of carbohydrate-metabolizing enzymes; (b) reduction of glucose transporters expression or activity; (c) inhibition of glycogenolysis and (d) modulation of gut microbiota by anthocyanin breakdown products. These strategies may be achieved through administration of individual anthocyanins or by functional foods containing complexes of anthocyanin:carbohydrate:protein.

scholarly journals Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 576
Author(s):  
Yen-Wen Shen ◽  
Yuen-Shan Tsai ◽  
Jui-Ting Hsu ◽  
Ming-You Shie ◽  
Heng-Li Huang ◽  
...  
Keyword(s):  
Computational Models ◽  
Titanium Implant ◽  
Biomechanical Properties ◽  
In Vitro Experiments ◽  
Element Analysis ◽  
Group Function ◽  
Computed Tomography Images ◽  
Porous Implant ◽  
3D Printed

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost’s mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations.

Numerical Prediction of Influence of Diamond Burs on Subsurface Damage in Intraoral Adjustments of Porcelain Prostheses

2008 ◽  
Vol 32 ◽  
pp. 203-206
Author(s):  
Xiao Fei Song ◽  
Ling Yin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Modeling ◽  
Material Removal ◽  
High Speed ◽  
Surface Damage ◽  
Subsurface Damage ◽  
Element Analysis ◽  
Made In

Failure rate is noticeably high in dental bioceramics for restorations even though progress has been made in reinforcement of the materials. One of the major causes of failures is due to surface and subsurface damage induced in intraoral adjustments. This process is a routine clinical procedure for marginal and occlusal fit using high-speed dental handpieces and diamond burs. Material removal using the diamond burs easily produce surface and subsurface damage in ceramic prostheses. Therefore, it is essential to minimize the surface damage in clinical dentistry. In this paper, we investigated the effect of diamond burs with coarse, medium and fine grit sizes on the degrees of subsurface damage in in vitro dental adjustments via numerical modeling. Finite element analysis was applied to model the dental adjusting processes and to predict the degrees of subsurface damage using different grit sizes of diamond burs.

scholarly journals Comparison of Stresses in Monoblock Tilted Implants and Conventional Angled Multiunit Abutment-implant Connection Systems in the All-on-four Procedure

2020 ◽  
Author(s):  
Özge Özdal Zincir ◽  
Ateş Parlar
Keyword(s):  
Biomechanical Properties ◽  
Principal Stresses ◽  
Element Analysis ◽  
Edentulous Mandible ◽  
Group A ◽  
Bacterial Accumulation ◽  
Group B ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Implant System

Abstract Background: The All-on-four dental implant method is an implantology method designed to provide a comfortable prosthetic treatment option by avoiding advanced surgical procedures. This research aims to compare and evaluate the stress and tension values in conventional angled multiunit abutment-implant connection systems and monoblock dental implants used in the all-on-four procedure with finite element analysis.Methods: Two master models were created by placing four implants connected to multiunit abutments (group A) in the interforaminal region of a completely edentulous mandible and four monoblock implants (group B) in the same region of another completely edentulous mandible. Group A implants were classified according to their diameter as follows: 3.5 mm (M1A), 4.0 mm (M2A), and 4.5 mm (M3A). Similarly, group B implants were classified as M1B, M2B, and M3B. In the six models rehabilitated with acrylic fixed prostheses, a 100 N force was applied to the anterior implant region, and a 250 N force was applied to the posterior cantilever in both axial and 30° oblique directions. Von Mises stresses were analyzed in the bone and implant regions of all models.Results: M1A and M1B, M2A and M2B, and M3A and M3B were compared with each other under axial and oblique forces. The maximum Von Mises stresses in the bone around implants and the prosthesis screws, and the maximum and minimum principal stresses in the cortical and trabecular bone in group A models were significantly higher than those in group B models.Conclusions: This study shows that the use of monoblock implants without abutment-implant connections can prevent bacterial accumulation in micro-gaps, but the biomechanical properties of this implant system should be improved.

Synthesis and characterization of Sr-doped HAp-incorporated polyether ether ketone composite

2019 ◽  
Vol 54 (3) ◽  
pp. 287-298
Author(s):  
Anindya Pal ◽  
Bhabatosh Biswas ◽  
Ankita Das ◽  
Arindam Chakraborty ◽  
Pallab Datta ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Hot Isostatic Pressing ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Polyether Ether Ketone ◽  
Transmission Electron ◽  
Uniform Dispersion ◽  
The Matrix ◽  
Ether Ketone

Hydrothermally synthesized undoped and Sr-doped hydroxyapatite-dispersed polyether ether ketone composites has been fabricated by using hot isostatic pressing technique with 5, 10, 15, and 20 wt.% as the dispersoids content. The detailed structural investigation of the fabricated composites has been performed by scanning electron microscope, high-resolution transmission electron microscope, and X-ray diffraction technique that confirmed the uniform dispersion of the dispersoids with the polyether ether ketone matrix. The microindentation measurements show that the mechanical properties of the polyether ether ketone matrix improved remarkably with incorporation of the hydroxyapatite (HAp) particles. The nondestructively evaluated elastic modulus so obtained for the matrix and composites were further validated through finite element analysis. Moreover, the in vitro cytotoxic of the fabricated nanocomposites were also evaluated to assess its potential as a bioactive material.

scholarly journals An Organotypic Mammary Duct Model Capturing Distinct Events of DCIS Progression

2020 ◽  
Author(s):  
Jonathan Kulwatno ◽  
Xiangyu Gong ◽  
Rebecca DeVaux ◽  
Jason I. Herschkowitz ◽  
Kristen Lynn Mills
Keyword(s):  
Breast Cancer ◽  
Cell Lines ◽  
Cancer Progression ◽  
Ductal Carcinoma ◽  
Biomechanical Properties ◽  
Breast Cancer Progression ◽  
Surrounding Tissue ◽  
Mammary Duct ◽  
The Matrix

ABSTRACTDuctal carcinoma in situ (DCIS) is a pre-cancerous stage breast cancer, where abnormal cells are contained within the duct, but have not invaded into the surrounding tissue. However, only 30-40% of DCIS cases are likely to progress into an invasive ductal carcinoma (IDC), while the remainder are innocuous. Since little is known about what contributes to the transition from DCIS to IDC, clinicians and patients tend to opt for treatment, leading to concerns of overdiagnosis and overtreatment. In vitro models are currently being used to probe how DCIS transitions into IDC, but many models do not take into consideration the macroscopic tissue architecture and the biomechanical properties of the microenvironment. Here, we developed an organotypic mammary duct model by molding a channel within a collagen matrix and lining it with a basement membrane. By adjusting the concentration of collagen, we effectively modulated the stiffness and morphological properties of the matrix and examined how an assortment of breast cells responded to changing density and stiffness of the matrix. We first validated the model using two established, phenotypically divergent breast cancer cell lines by demonstrating the ability of the cells to either invade (MDA-MB-231) or cluster (MCF7). We then examined how cells of the isogenic MCF10 series—spanning the range from healthy to aggressive—behaved within our model and observed distinct characteristics of breast cancer progression such as hyperplasia and invasion, in response to collagen concentration. Our results show that the model can recapitulate different stages of breast cancer progression and that the MCF10 series is adaptable to physiologically relevant in vitro studies, demonstrating the potential of both the model and cell lines to elucidate key factors that may contribute to understanding the transition from DCIS to IDC.IMPACT STATEMENTThe success of early preventative measures for breast cancer has left patients susceptible to overdiagnosis and overtreatment. Limited knowledge of factors driving an invasive transition has inspired the development of in vitro models that accurately capture this phenomenon. However, current models tend to neglect the macroscopic architecture and biomechanical properties of the mammary duct. Here, we introduce an organotypic model that recapitulates the cylindrical geometry of the tissue and the altered stroma seen in tumor microenvironments. Our model was able to capture distinct features associated with breast cancer progression, demonstrating its potential to uncover novel insights into disease progression.

Radiolabeled r-Hirudin as a Measure of Thrombin Activity at, or within, the Rabbit Aorta Wall In Vitro and In Vivo

1994 ◽  
Vol 71 (04) ◽  
pp. 499-506 ◽  
Author(s):  
Mark W C Hatton ◽  
Bonnie Ross-Ouellet
Keyword(s):  
Rabbit Aorta ◽  
Balloon Injury ◽  
Recombinant Hirudin ◽  
Aorta Wall ◽  
Thrombin Activity ◽  
Before And After ◽  
The Matrix

SummaryThe behavior of 125I-labeled recombinant hirudin towards the uninjured and de-endothelialized rabbit aorta wall has been studied in vitro and in vivo to determine its usefulness as an indicator of thrombin activity associated with the aorta wall. Thrombin adsorbed to either sulfopropyl-Sephadex or heparin-Sepharose bound >95% of 125I-r-hirudin and the complex remained bound to the matrix. Binding of 125I-r-hirudin to the exposed aorta subendothelium (intima-media) in vitro was increased substantially if the tissue was pre-treated with thrombin; the quantity of l25I-r-hirudin bound to the de-endothelialized intima-media (i.e. balloon-injured in vitro) correlated positively with the quantity of bound 131I-thrombin (p <0.01). Aortas balloon-injured in vivo were measured for thrombin release from, and binding of 125I-r-hirudin to, the de-endothelialized intimal surface in vitro; 125I-r-hirudin binding correlated with the amount of active thrombin released (p <0.001). Uptake of 125I-r-hirudin by the aorta wall in vivo was proportional to the uptake of 131I-fibrinogen (as an indicator of thrombin activity) before and after balloon injury. After 30 min in the circulation, specific 125I-r-hirudin binding to the uninjured and de-endo- thelialized (at 1.5 h after injury) aorta wall was equivalent to 3.4 (± 2.5) and 25.6 (±18.1) fmol of thrombin/cm2 of intima-media, respectively. Possibly, only hirudin-accessible, glycosaminoglycan-bound thrombin is measured in this way.

Formulation and Evaluation of Galantamine Hydrobromide Floating Matrix Tablet

2018 ◽  
Vol 8 (2) ◽  
Author(s):  
Poreddy Srikanth Reddy ◽  
Penjuri Subhash Chandra Bose ◽  
Vuppula Sruthi ◽  
Damineni Saritha
Keyword(s):  
Sodium Alginate ◽  
Xanthan Gum ◽  
Lag Time ◽  
Matrix Tablets ◽  
In Vitro Dissolution ◽  
Matrix Tablet ◽  
Compression Technique ◽  
Weight Variation ◽  
The Matrix

The aim of the present work was to prepare floating tablets of galantamine HBr using sodium alginate and xanthan gum as matrix forming carriers. Galantamine HBr is used for the treatment of mild to moderate Alzheimer's disease and various other memory impairments, in particular those of vascular origin. The matrix tablet formulations were prepared by varying the concentrations of sodium alginate and xanthan gum. The tablets were prepared by direct compression technique using PVP K-30 as a binder and sodium bicarbonate for development of CO2. The prepared matrix tablets were evaluated for properties such as hardness, thickness, friability, weight variation, floating lag time, compatibility using DSC and FTIR. In vitro dissolution was carried out for 12 hrs in 0.1N HCl at 37±0.5 ºC using USP paddle type dissolution apparatus. It was noted that, all the prepared formulations had desired floating lag time and constantly floated on dissolution medium by maintaining the matrix integrity. The drug release from prepared tablets was found to vary with varying concentration of the polymers, sodium alginate and xanthan gum. From the study it was concluded that floating drug delivery system for galantamine HBr can be prepared by using sodium alginate and xanthan gum as a carrier.

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