Computational model of the cancer necrotic core formation in a tumor-on-a-chip device.

The mechanisms underlying the formation of necrotic regions within avascular tumors are complex and poorly understood. In this paper, we investigate the formation of a necrotic core in a 3D tumor cell culture within a microfluidic device, considering oxygen, nutrients, and the microenvironment acidification by means of a computational-mathematical model. Our objective is to simulate cell processes, including proliferation and death inside a microfluidic device, according to the microenvironmental conditions.

Biomechanical evaluation of acromioclavicular joint reconstructions using a 3-dimensional model based on the finite element method.

Background: This study aims to evaluate the influence of stabilization of acromioclavicular (AC) joint dislocation through the modified Weaver-Dunn technique and coracoclavicular (CC) ligaments using the finite element method. The goal is to determine which surgical technique allows behavior that is most similar to the joint, guaranteeing the necessary stability without restricting joint movements for the considered conditions.

Methods: The analysis is based on the three-dimensional finite element models.

Mechanical Study of the Properties of Sutures used in Orthopedics Surgeries.

 To evaluate the mechanical properties of sutures commonly used in orthopedic surgeries, characterizing their behavior through tensile tests and determining which one has greater mechanical strength.  Tensile tests of different sutures were performed in a mechanical testing machine BME 10 kN, using a 50 kgf maximum capacity loading cell. Seven samples from each suture material were tested.

Bioimpedance as an indicator in the distribution of interface pressure in vulnerable regions for pressure ulcers: A preliminary study.

Aim: To examine the influence of body mass index, bioimpedance, and skin folds on the distribution of body interface pressure in regions with the potential to develop pressure ulcers in contact with support surfaces.

Design: This was a descriptive and analytical study.

Methods: Twenty healthy volunteer adults were investigated in April 2017.

Support surfaces in the prevention of pressure ulcers in surgical patients: An integrative review.

Aim: To assess the scientific evidence about the types of support surfaces used in intraoperative surgical practice in the prevention of pressure ulcers due to surgical positioning.

Method: This is an integrative literature review. The electronic databases Cochrane, PubMed, Web of Science, Scopus, Lilacs, and CINAHL were used.

Influence of Screw Surface Treatment on Retention of Implant-Supported Fixed Partial Dentures.

The aim of this study was to assess the effect of a diamond-like carbon (DLC) coating on the removal torque of prefabricated implant screws after cyclic loading. Four groups with two crowns supported by two implants (n = 5) were obtained according to splinted and nonsplinted prosthesis, using titanium or DLC screws (splinted crowns with titanium screw [STi], splinted crowns with DLC screw [SC], nonsplinted crowns and titanium screw [NSTi], and nonsplinted crowns and DLC screw [NSC]). The prosthetic screws were tightened at 32 Ncm and retightened, and the specimens were submitted to 106 mechanical cycles (4 Hz/98 N).

Fracture Resistance of Internal Conical and External Hexagon: Regular and Narrow Implant-Abutment Assemblies.

Purpose: The aim of this study was to compare the maximum load on the elastic limit of internal conical (IC) implants with regular external hexagon (REH) and narrow external hexagon (NEH) implants.

Materials And Methods: Thirty cylindrical implants were divided in 3 groups (n = 10): REH (3.75 mm); NEH (3.

Stress distribution in implant-supported prostheses using different connection systems and cantilever lengths: digital photoelasticity.

Photoelastic analysis was used to evaluate the biomechanical behaviour of implant-supported, double-screwed crowns with different connection systems and cantilever lengths. Three models were made in PL-2 photoelastic resin and divided into six groups, on the basis of the implant connection system (external hexagon [EH] or Morse taper [MT]), type of abutment (Mini Pilar [Neodent, Curitiba, Paraná, Brazil] or "UCLA") and number of crowns in the cantilever (one or two). The implant-prosthesis unit was placed in a circular polariscope.

Photoelastic stress analysis of mandibular fixed prostheses supported by 3 dental implants.

Purpose: To observe the photoelastic stress patterns generated around implants in relation to variations in the diameter and total number of implants supporting fixed complete-arch mandibular frameworks.

Materials And Methods: Three different implant configurations were analyzed (n = 3): 5 standard implants with diameters of 3.75 mm (C), 3 standard implants with diameters of 3.

Analysis of stress induced by screws in the vertebral fixation system.

Objective: To compare, using photoelasticity, internal stress produced by USS II type screw with 5.2 and 6.2 mm external diameters, when submitted to three different pullout strengths.

Stress distribution in Co-Cr implant frameworks after laser or TIG welding.

Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform.

Distribution of peri-implant stresses with a countertorque device.

Purpose: To verify the effectiveness of a countertorque device in dental implants in redistributing stress to the bone-implant interface during tightening of the abutment screw.

Materials And Methods: Two prismatic photoelastic samples containing implants were made, one with a 3.75-mm-diameter implant and the other with a 5.

The influence of interproximal contact on implant-supported fixed partial dentures in the posterior jaw: a photoelastic analysis.

The aim of this study was to analyze the effect of the separation of prosthetic crowns from fixed partial dentures by means of stress gradient evaluation. Three photoelastic models were created to examine contiguous implants with varying contact between the crowns (contact point [CP], contact surface [CS], splinted [SP]). The SP group presented the best results, followed by the CS group, indicating that the use of splinted prosthetic crowns and crowns with broad surface contacts is viable when considering the stress values.

Photoelastic stress analysis of different wide implant/abutment interfaces under oblique loading.

Purpose: There is a variety of implant/abutment (I/A) junctions for the connection of implant-supported prostheses. The aim of this work was to compare the shear stress distribution in three types of I/A interfaces after application of oblique loading on the abutments, simulating loading on an anterior tooth.

Materials And Methods: Similar wide unthreaded and cylindric implants (13.

Effect of plasma welding parameters on the flexural strength of Ti-6Al-4V alloy.

The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10).

Ergonomic analysis in cold storage rooms: a study of case.

The human work possess a history and, in this dimension, the man is submitted to the conditions that confer it physical and psychological consequences. The activity of work in the present time imposes adverse labor conditions. The ergonomics is a science that it aims at to study the real activity of the work with sights its transformation.

Photoelastic analisys in the lower region of vertebral body L4.

Objective: To analyze the shear forces on the vertebral body L4 when submitted to a compression force by means of transmission photoelasticity.

Methods: Twelve photoelastic models were divided into three groups, with four models per group, according to the positioning of the sagittal section vertebrae L4-L5 (sections A, B and C). The simulation was performed using a 15N compression force, and the fringe orders were evaluated in the vertebral body L4 by the Tardy compensation method.

Photoelastic analysis of stress patterns from different implant-abutment interfaces.

Purpose: To investigate the peri-implant stress fields generated from four different implant-abutment interfaces under axial loading applied at the center of the implant and several millimeters away from the implant center via photoelastic analysis.

Materials And Methods: Similar unthreaded and cylindric implants and abutments were fabricated and embedded in photoelastic resin with four different implant-abutment interfaces: external hex, internal hex, internal taper (11.5 degrees), and solid connection to the abutment (one piece).

Influence of restorative technique on the biomechanical behavior of endodontically treated maxillary premolars. Part II: strain measurement and stress distribution.

Statement Of Problem: Unresolved controversy exists concerning the preferred cavity design and restorative technique used to restore endodontically treated maxillary premolars to minimize strain and improve stress distribution under occlusal load.

Purpose: The purpose of this study was to analyze the influence of cavity design and restorative material on strain measurement and stress distribution in maxillary premolars under occlusal loading conditions, and correlate these influences with the failure modes analyzed in Part I.

Material And Methods: For the strain gauge test, 21 additional specimens were prepared as described in Part 1 of this study (n=3).

Fracture resistance and stress distribution in endodontically treated maxillary premolars restored with composite resin.

Purpose: The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth.

Materials And Methods: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.