scholarly journals Comparison of two different screw trajectories in the treatment of oblique scaphoid fractures: A mechanical study on composite bone models

2021 ◽  
Vol 32 (2) ◽  
pp. 377-382
Author(s):  
Bülent Kılıç ◽  
Mustafa Çalışkan ◽  
Anıl Agar ◽  
Bora Uzun ◽  
Fatih Ertem ◽  
...  
Keyword(s):  
Testing Machine ◽  
Axial Loading ◽  
Scaphoid Bone ◽  
Maximum Displacement ◽  
Bone Model ◽  
Scaphoid Fractures ◽  
Significant Difference ◽  
Mechanical Study ◽  
The Stability ◽  
Composite Bone

Objectives: In this mechanical study, we aimed to compare two different screw trajectories in terms of durability against axial loads on oblique scaphoid fractures using composite bone models. Materials and methods: Oblique osteotomies were made along the dorsal sulcus of 14 composite scaphoid bone models. Following this, all bone models were randomly classified. One group of bones were fixed with a screw placed perpendicular to the osteotomy line and the other group was fixed with a screw placed centrally down the long axis of the scaphoid bone. Each scaphoid bone model was positioned on a mechanical testing machine. Subsequently, axial loading tests were applied on each bone model to measure the amount of loading required to cause 2-mm displacement and failure on the osteotomy side and maximum displacement at the time of failure on scaphoid bone models. Results: There was no statistically significant difference in load to 2-mm displacement and failure between the two groups (p>0.05). Also, there was no statistically significant difference between the two groups in terms of maximum displacement seen on failure (p>0.05). Conclusion: In our study, we found that the stability of the screws which laid perpendicular to the fracture line and parallel to the long axis of the scaphoid was the same in fixing oblique scaphoid fractures.

Comparison of Mechanical Properties between Thai Orthodontic Elastics with Different Ammonia Contents and Commercial Orthodontic Elastics

2011 ◽  
Vol 378-379 ◽  
pp. 580-584
Author(s):  
N. Anuwongnukroh ◽  
Porntiwa Senarak ◽  
Surachai Dechkunakorn ◽  
Theeralaksna Suddhasthira ◽  
C. Kongkaew ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Breaking Strength ◽  
Testing Machine ◽  
Natural Rubber Latex ◽  
Rubber Latex ◽  
Maximum Displacement ◽  
Significant Difference ◽  
Extension Force ◽  
Residual Force

Introduction: The most widely used preservative system for natural rubber latex to date is the ammonia-based system preventing spontaneous coagulation and putrefaction due mainly to bacteria contamination. Objectives: The study compared 2 types of Thai orthodontic elastics, produced from natural rubber latex with different ammonia contents with commercial orthodontic elastics in terms of initial extension force, residual force, force loss, swelling index, breaking strength and maximum displacement. Materials and Methods: Thai orthodontic elastics were developed from 2 types of natural rubber latex; low ammonia < 0.15% (Thai-L), and high ammonia not < 0.6% (Thai-H). The mechanical properties of Thai orthodontic elastics were compared with commercial elastics (Ormco). Mechanical properties were tested using a universal testing machine (Instron 5566). Data were analyzed by One-way ANOVA and Tukey’s test compared the measurements among groups. Results: Ormco had the highest initial extension force and showed significant differences with Thai-L and Thai-H. Thai-L had the highest residual force but showed no significant difference compared with Ormco. Thai-L had the lowest percent of force loss and showed significant differences with Thai-H and Ormco. Thai-L had lower force loss than Thai-H. For swelling index, Thai-L had the highest elasticity. For breaking strength and maximum displacement, both Thai elastics met the Australian Standard (AS) for breaking strength and maximum displacement, similar to Ormco elastics. Conclusion: All elastics met the specifications of the AS for breaking strength and maximum displacement. Thai-L had comparable properties with commercial orthodontic elastics in terms of mechanical properties. Thai-L had comparable properties with Ormco in terms of mechanical properties and may be developed for orthodontic purposes.

scholarly journals Medially positioned plate in first metatarsophalangeal joint arthrodesis

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260572
Author(s):  
Wojciech Witkowski ◽  
Leszek Kuik ◽  
Magdalena Rucka ◽  
Karol Daszkiewicz ◽  
Angela Andrzejewska ◽  
...  
Keyword(s):  
Finite Element ◽  
Locking Plate ◽  
Healing Process ◽  
Testing Machine ◽  
Metatarsophalangeal Joint ◽  
Dorsal Plate ◽  
Maximum Displacement ◽  
First Metatarsophalangeal Joint ◽  
Hardware Failure ◽  
The Stability

Objective The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates. Methods A physical model of the MTP1 joint consists of printed synthetic bones, a titanium locking plate and screws. In the experiments, samples with dorsally and medially positioned plates were subjected to loading of ground load character in a universal testing machine. Force-displacement relations and relative displacements of bones were recorded. The obtained results were used to validate the corresponding finite element models of the MTP1 joint. Nonlinear finite element simulations of the toe-off phase of gait were performed to determine the deformation and stress state in the MTP1 joint for two positions of the plate. Results In numerical simulations, the maximum displacement in the dorsal direction was noticed at the tip of the distal phalanx and was equal to 19.6 mm for the dorsal plate and 9.63 mm for the medial plate for a resultant force of 150 N. Lower relative bone displacements and smaller plastic deformation in the plate were observed in the model with the medial plate. Stress values were also smaller in the medially positioned plate and locking screws compared to fixation with the dorsal plate. Conclusions A medially positioned locking plate provides better stability of the MTP1 joint than a dorsally positioned plate due to greater vertical bending stiffness of the medial plate. Smaller relative bone displacements observed in fixation with the medial plate may be beneficial for the bone healing process. Moreover, lower stress values may decrease the risk of complications associated with hardware failure.

Three Dimensional Fluoroscan is More Accurate and Repeatable Than Two Dimensional Fluoroscan for Measuring Central Scaphoid Screw Placement in a Cadaver Model

2010 ◽  
Author(s):  
Hyun Kyu Han ◽  
W. Scott Green ◽  
Jenni M. Buckley ◽  
Lisa L. Lattanza
Keyword(s):  
Three Dimensional ◽  
Treatment Method ◽  
Screw Placement ◽  
Scaphoid Bone ◽  
Ct Reconstruction ◽  
Cast Immobilization ◽  
Scaphoid Fractures ◽  
Significant Difference ◽  
Screw Malpositioning ◽  
Fluoroscopic Imaging

A commonly accepted treatment method for scaphoid fractures is dorsal percutaneous fixation [1, 2]. This has been shown to decrease the need for cast immobilization and allow faster recovery [3, 4]. For this approach a central screw placement is critical as it provides greater stiffness and load to failure, and allows a longer screw to be inserted which increases screw compression. All of these factors aid in fracture union [5]. However, the complex shape of the scaphoid bone makes central screw placement difficult, as the main axis cannot be easily visualized. Currently, scaphoid screws are placed using K wires guided under 2D fluoroscopy; however, intra-operative 3D fluoroscopy, which can create a CT reconstruction, is becoming more readily available. The goals of this study are to see if there is a significant difference between 2D and 3D fluoroscopic imaging in measuring screw malpositioning (distance off-center) and if there is a difference in repeatability.

The Influence of Force Direction on the Fracture Pattern and Fracture Resistance of Canine Teeth in Dogs

2017 ◽  
Vol 34 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Stephanie Goldschmidt ◽  
Catherine Zimmerman ◽  
Caitlyn Collins ◽  
Scott Hetzel ◽  
Heidi-Lynn Ploeg ◽  
...  
Keyword(s):  
Fracture Resistance ◽  
Ex Vivo ◽  
Testing Machine ◽  
Fracture Pattern ◽  
Hard Tissue ◽  
Canine Tooth ◽  
Cross Sectional ◽  
Significant Difference ◽  
Force Direction ◽  
Testing Group

Biomechanical studies of the elongated canine tooth of animals are few, and thus our understanding of mechanical and physical properties of animal teeth is limited. The objective of the present study was to evaluate the influence of force direction on fracture resistance and fracture pattern of canine teeth in an ex vivo dog cadaver model. Forty-five extracted canine teeth from laboratory beagle dogs were standardized by hard tissue volume and randomly distributed among 3 force direction groups. The teeth were secured within a universal testing machine and a load was applied at different directions based on testing group. The maximum force to fracture and the fracture pattern classification were recorded for each tooth. After correcting for hard tissue cross-sectional area in a multivariate analysis, no significant difference in the amount of force required for fracture was apparent between the different force direction groups. However, the influence of force direction on fracture pattern was significant. The results of this study may allow the clinician to educate clients on possible causal force directions in clinically fractured teeth and, thus, help prevent any contributing behavior in the future.

Stability and mutual impact of perception of parental pressure and infants' social support – A study based on the difference between employment status and household income

2021 ◽  
pp. 002072092199705
Author(s):  
Yong Wang
Keyword(s):  
Household Income ◽  
Employment Status ◽  
Working Mothers ◽  
Social Research ◽  
Research Report ◽  
Parental Pressure ◽  
Income Levels ◽  
Significant Difference ◽  
The Difference ◽  
The Stability

The purpose of this study is to explore the stability and interaction between parental pressure and social research report, as well as the role of employment status and family income levels in this process. This study used a special study on Korean children (PSKC) 2–4 waves. Use t-test, correlation and autoregressive cross-delay modeling to analyze the data. The main findings of this study are: First, over time, parental pressure and mother’s social research report are consistent. Secondly, the pressure of motherhood and childcare has an obvious lagging effect on upbringing, and vice versa. Third, there is no significant difference between working mothers and non-working mothers in terms of the stability of working parents' pressure, social research report and social research report for children's pressure channels. However, parental pressure can only predict the social research report of working mothers. Fourth, there is no significant difference between the stability and interaction of these two structures in household income levels. In short, the results show that, over time, parental pressure is consistent with mother’s social research report. The results also show that there is a significant cross-lag effect between the mothers’ perceptions of mutual pressure analysis. In the process from parental pressure to social research report, I found the difference between working and non-working mothers. The advantage of this study is that the expected longitudinal design was adopted during infancy and the priority between the two structures can be considered. The results of this study can be used as a source of intervention plans to help parents withstand severe parenting pressure and lack of social research report.

Crush Response of Polyurethane Foam-Filled Aluminium Tube Subjected to Axial Loading

2014 ◽  
Vol 875-877 ◽  
pp. 534-541 ◽  
Author(s):  
Chawalit Thinvongpituk ◽  
Nirut Onsalung
Keyword(s):  
Energy Absorption ◽  
Polyurethane Foam ◽  
Testing Machine ◽  
Axial Loading ◽  
Asymmetric Mode ◽  
Pu Foam ◽  
Universal Testing ◽  
Collapse Mode ◽  
Empty Tube ◽  
Foam Filled

In this paper, the experimental investigation of polyurethane (PU) foam-filled into circular aluminum tubes subjected to axial crushing was presented. The purpose of this study is to improve the energy absorption of aluminium tube under axial quasi-static load. The aluminium tube was made from the AA6063-T5 aluminium alloy tubes. Each tube was filled with polyurethane foam. The density of foam was varied from 100, 150 and 200 kg/mP3P including with empty tube. The range of diameter/thickness (D/t) ratio of tube was varied from 15-55. The specimen were tested by quasi-static axial load with crush speed of 50 mm/min using the 2,000 kN universal testing machine. The load-displacement curves while testing were recorded for calculation. The mode of collapse of each specimen was analyzed concerning on foam density and the influence of D/t ratio. The results revealed that the tube with foam-filled provided significantly increment of the energy absorption than that of the empty tube. While the density of foam and D/t ratios increase, the tendency of collapse mode is transformed from asymmetric mode to concertina mode.

scholarly journals Comparative Evaluation of Fracture Resistance of Endodontically Treated Teeth Restored with Resin Fiber Post and Stainless Steel Post: An In Vitro Study

2015 ◽  
Vol 03 (02) ◽  
pp. 080-084
Author(s):  
Vijay Singh ◽  
Poonam Bogra ◽  
Saurabh Gupta ◽  
Navneet Kukreja ◽  
Neha Gupta
Keyword(s):  
Stainless Steel ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Compressive Force ◽  
Control Group ◽  
Fiber Post ◽  
Endodontically Treated Teeth ◽  
Group I ◽  
Significant Difference

AbstractFracture resistance of endodontically treated teeth restored with post. Aims: This study aims to compare the fracture resistance of endodontically treated teeth restored with resin fiber and stainless steel post. Commercially available prefabricated resin fiber post(Dentsply Maillefer Easy Post), prefabricated stainless steel post(Coltene/Whaledent Parapost) were used. Methods and Material: Forty five maxillary central incisors were obturated and divided into 3 groups: Control Group (Group I) without any post (n = 15), Resin Fiber Post Group (Group II) (n = 15) and Stainless Steel Post Group (Group III) (n = 15). In all Groups except control group, post space was prepared; a post was cemented, and a core build-up was provided. All the specimens were subjected to compressive force under a universal testing machine until fracture. Statistical analysis used: The results were analyzed using the variable analysis test (ANOVA). Results: One-way analysis of variance revealed significant difference among test groups. The control group demonstrated highest fracture resistance (925.2183 N), followed by the resin fiber post group (486.7265 N) and stainless steel post group (423.539N). Conclusions: Teeth restored with resin fiber post showed higher fracture resistance values than prefabricated stainless steel post.

scholarly journals Shear bond strength of novel calcium aluminate-based cement (EndoBinder) to root dentine

2014 ◽  
Vol 08 (04) ◽  
pp. 498-503 ◽  
Author(s):  
Lucas da Fonseca Roberti Garcia ◽  
Hebert Luis Rossetto ◽  
Fernanda de Carvalho Panzeri Pires-de-Souza
Keyword(s):  
Bond Strength ◽  
Calcium Aluminate ◽  
Shear Bond Strength ◽  
Testing Machine ◽  
Mineral Trioxide Aggregate ◽  
Acrylic Resin ◽  
Promising Alternative ◽  
Mean Values ◽  
Significant Difference ◽  
Molar Teeth

ABSTRACT Objective: To evaluate the shear bond strength of a novel calcium aluminate-based cement, EndoBinder (EB), to dentine in comparison with Grey and White Mineral Trioxide Aggregate (MTA). Materials and Methods: Root canal hemi-sections obtained from 30 extracted molar teeth were embedded in self-polymerized acrylic resin and were grounded wet in order to obtain a flat dentine surface. Next, the roots were randomly assigned into three groups (n = 10), according to the cement used, as follows: EB: EndoBinder; WMTA: White MTA and GMTA: Grey MTA. The shear bond strength test was performed using a Universal Testing Machine (0.5 mm/min) and the data were submitted to statistical analysis (1-way ANOVA and Tukey tests, P < 0.05). Results: EB presented the highest shear bond strength values; however, there was no statistically significant difference in comparison with GMTA (P > 0.05). WMTA presented the lowest mean values, which were significant in comparison with EB (P < 0.05). Conclusions: The novel calcium aluminate-based cement presented higher shear bond strength than WMTA, and should be considered as a promising alternative in endodontic therapy.

scholarly journals Biomechanical properties of the bone during implant placement

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ádám László Nagy ◽  
Zsolt Tóth ◽  
Tamás Tarjányi ◽  
Nándor Tamás Práger ◽  
Zoltán Lajos Baráth
Keyword(s):  
Bone Structure ◽  
Biomechanical Properties ◽  
Control Group ◽  
Dynamic Tests ◽  
Bone Model ◽  
Implant Placement ◽  
Significant Difference ◽  
Before And After ◽  
Group 2 ◽  
Post Hoc

Abstract Background In this research the biomechanical properties of a bone model was examined. Porcine ribs are used as experimental model. The objective of this research was to investigate and compare the biomechanical properties of the bone model before and after implant placement. Methods The bone samples were divided in three groups, Group 1 where ALL-ON-FOUR protocol was used during pre-drilling and placing the implants, Group 2 where ALL-ON-FOUR protocol was used during pre-drilling, and implants were not placed, and Group 3 consisting of intact bones served as a control group. Static and dynamic loading was applied for examining the model samples. Kruskal–Wallis statistical test and as a post-hoc test Mann–Whitney U test was performed to analyze experimental results. Results According to the results of the static loading, there was no significant difference between the implanted and original ribs, however, the toughness values of the bones decreased largely on account of predrilling the bones. The analysis of dynamic fatigue measurements by Kruskal–Wallis test showed significant differences between the intact and predrilled bones. Conclusion The pre-drilled bone was much weaker in both static and dynamic tests than the natural or implanted specimens. According to the results of the dynamic tests and after a certain loading cycle the implanted samples behaved the same way as the control samples, which suggests that implantation have stabilized the skeletal bone structure.

scholarly journals How Many Proximal Screws Are Needed for a Stable Proximal Humerus Fracture Fixation?

2021 ◽  
Vol 12 ◽  
pp. 215145932199274
Author(s):  
Hyojune Kim ◽  
Myung Jin Shin ◽  
Erica Kholinne ◽  
Janghyeon Seo ◽  
Duckwoo Ahn ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Proximal Humerus Fracture ◽  
Locking Plate ◽  
Proximal Humerus ◽  
Humerus Fracture ◽  
Proximal Fragment ◽  
Maximum Displacement ◽  
Significant Difference ◽  
Load To Failure ◽  
Screw Group

Purpose: This biomechanical study investigates the optimal number of proximal screws for stable fixation of a 2-part proximal humerus fracture model with a locking plate. Methods: Twenty-four proximal humerus fracture models were included in the study. An unstable 2-part fracture was created and fixed by a locking plate. Cyclic loading and load-to-failure tests were used for the following 4 groups based on the number of screws used: 4-screw, 6-screw, 7-screw, and 9-screw groups. Interfragmentary gaps were measured following cyclic loading and compared. Consequently, the load to failure, maximum displacement, stiffness, and mode of failure at failure point were compared. Results: The interfragmentary gaps for the 4-screw, 6-screw, 7-screw, and 9-screw groups were significantly reduced by 0.24 ± 0.09 mm, 0.08 ± 0.06 mm, 0.05 ± 0.01 mm, and 0.03 ± 0.01 mm following 1000 cyclic loading, respectively. The loads to failure were significantly different between the groups with the 7-screw group showing the highest load to failure. The stiffness of the 7-screw group was superior compared with the 6-screw, 9-screw, and 4-screw groups. The maximum displacement before failure showed a significant difference between the comparative groups with the 4-screw group having the lowest value. The 7-screw group had the least structural failure rate (33.3%). Conclusion: At least 7 screws would be optimal for proximal fragment fixation of proximal humerus fractures with medial comminution to minimize secondary varus collapse or fixation failure. Level of Evidence: Basic science study.

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