Mechanical Behavior of Bamboo Species Guadua angustifolia under Compression along the Thickness of the Culm

2014 ◽  
Vol 600 ◽  
pp. 49-56 ◽  
Author(s):  
Gustavo Orozco ◽  
Laura Villegas ◽  
José Jaime García
Keyword(s):  
Mechanical Behavior ◽  
Latin American ◽  
Radial Direction ◽  
Testing Machine ◽  
Ductile Material ◽  
Radial Compression ◽  
Bamboo Species ◽  
Hexahedral Elements ◽  
Significant Difference ◽  
Structural Joints

The bamboo species Guadua angustifolia is a natural functionally graded material with a high potential to help solving the housing deficit in Latin American countries. Bamboo plantations also play an important role to help reducing the devastation of tropical forests. Many studies have demonstrated the excellent mechanical properties of bamboo along the length of the culm. However, other properties like the strength under circumferential tension and shear are low and the associated types of failure are fragile. Therefore, longitudinal fissures are often initiated in the structural joints which avoid taking advantage of the high resistance along the longitudinal direction. To the best of our knowledge, no study has been devoted to study the mechanical behavior of bamboo along the thickness of the culm or radial direction. This characterization may be crucial to improve the performance of the joints in bamboo structures. The aim of this study was to determine the strength and the Young ́s modulus of Guadua angustifolia along the radial direction. Thus, 27 small hexahedral elements of approximately 11 mm × 6 mm × 7 mm were tested under compression along the thickness of the culm. The stress-strain curves depicted a typical ductile behavior with an average failure strain of 37.8 ± 5.4 %. The failure was characterized by fissures on planes parallel to the fibers and forming angles in the range 35° - 55° with respect to the axis of loading. The secant Young ́s modulus and the radial strength were equal to 44.50 ±9.60 MPa, and 18.50 ±4.20 MPa respectively and there was no significant difference with position along the culm. The initial Young ́s modulus was equal to 96.73 ±52.30 MPa, 37.00 ±24.35 MPa and 48.90 ±7.31 MPa for the bottom, middle and upper portions of the culm and there was a significant difference (p=0.025) between the bottom and middle locations. The high variations of the initial Young ́s modulus may be explained by the irregular form of the surfaces of contact with the testing machine, that were not cut perfectly flat in order to preserve the intact material. These experiments show that Guadua behaves as a ductile material under compression along the thickness of the culm. This property may be used to improve the efficiency of structural joints by applying radial compression.

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.

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.

Design and Mechanical Evaluation of Sutureless Implants for the Surgery Treatment of Rotator Cuff Tears

2021 ◽  
Author(s):  
Marcília Valéria Guimarães ◽  
Elton Bonifácio ◽  
Thiago Carmo ◽  
Cleudmar Araújo
Keyword(s):  
Rotator Cuff ◽  
Mechanical Behavior ◽  
Functional Disability ◽  
Statistical Significance ◽  
Testing Machine ◽  
Rotator Cuff Tears ◽  
Suture Anchors ◽  
Pullout Strength ◽  
Rigid Foam ◽  
Pullout Tests

Abstract Rotator cuff (RC) tears cause pain and functional disability of the shoulder. Despite advances in suture anchors, there are still reports about the incidence of surgical-related injuries to RC mainly associated with sutures. The purpose of this study was to design and evaluate the mechanical behavior of sutureless implants to repair RC tears. We hypothesized that the implants present mechanical characteristics suitable for the surgical treatment of RC tears as suture anchors. Three different implants (T1,T2,T3) were designed and fabricated with titanium: T1 has two rods and rectangular head; T2 has two rods with a small opening and enlarged rectangular head and T3 has three rods and a circular head. The implants were fixed in rigid polyurethane foam blocks by a series of blows, and the applied mechanical loads along with the number of blows were quantified. Pullout tests using tapes fixed between the implant head and testing machine grip were conducted until implant failure. The maximum pullout strength and displacement of the implant relative to the rigid foam block were computed. Statistical significance was set at p &lt; 0.05. Owing to its geometric configuration, implant T2 presented the best characteristics related to stability, strength, and ease of insertion. Implant T2 confirms our hypothesis that its mechanical behavior is compatible with that of suture anchors which could lead to the reduction of RC repair failures and simplify the arthroscopic procedure.

Accessibility and public information of medical students’ Facebook profiles in Peru: A call to adapt e-professionalism guidelines in the Latin American context (Preprint)

2021 ◽  
Author(s):  
Carlos Jesús Aragón-Ayala ◽  
Henry Rodriguez-Carrillo ◽  
Aldor Cornejo-Estrada ◽  
Cender Udai Quispe-Juli
Keyword(s):  
Medical Students ◽  
Latin American ◽  
Social Networking Sites ◽  
Public Information ◽  
Male Students ◽  
The Public ◽  
Significant Difference ◽  
Professional Information ◽  
Types Of Information ◽  
The University

BACKGROUND Use of Facebook has increased and poses new challenges for adoption of professionalism. In this study we describe the accessibility of Facebook profiles in medical students, the disclosure of personal and professional information, and its association with sex and year of study. OBJECTIVE The purpose of this study was to explore the public accessibility of Facebook profiles of medical students from a Peruvian university and the disclosure of personal and professional information, as well as its association with sex and the year of studies. METHODS Through a systematic search on Facebook, the profiles of medical students from the 2nd to the 7th year were located using fictitious profiles. The presence of different types of information in accessible profiles were evaluated. Furthermore, the proportion of the disclosed content was calculated. The data were compared according to year of study and sex. RESULTS 80% of students (488/611) presented publicly accessible profiles. We did not find a significant difference according year of study (p = 0.098) and sex (p = 0.912). Proportion of disclosed content was greater in higher years: 2nd and 3rd (p = 0.022), 2nd and 6th (p < 0.001), and 2nd and 7th (p = 0.002) and in men (33.25 ± 12.47) compared to women (30.38 ± 11.95) (p = 0.01). Some photos (p = 0.009) and links to other social networking sites (p = 0.036) were more commonly visible in women’s profiles, while showing the university (p = 0.017), medical school (p = 0.043) and sexual orientation (p = 0.001) was more common amongst men. CONCLUSIONS Most of the Facebook profiles of medical students were accessible, the disclosed content was greater in senior and male students. It is necessary to create and implement guidelines on e-professionalism in Latin America.

scholarly journals Effect of Using Nano and Micro Airborne Abrasive Particles on Bond Strength of Implant Abutment to Prosthesis

2015 ◽  
Vol 26 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Mansour Rismanchian ◽  
Amin Davoudi ◽  
Elham Shadmehr
Keyword(s):  
Bond Strength ◽  
Testing Machine ◽  
Control Group ◽  
Abrasive Particles ◽  
Significant Difference ◽  
Implant Abutments ◽  
Implant Abutment ◽  
Roughened Surface ◽  
Bond Strengths ◽  
Spss Software

Connecting prostheses to the implant abutments has become a concern and achieving a satisfactory retention has been focused in cement-retention prostheses recently. Sandblasting is a method to make a roughened surface for providing more retention. The aim of this study was to compare effects of nano and micro airborne abrasive particles (ABAP) in roughening surface of implant abutments and further retention of cemented copings. Thirty Xive abutments and analogues (4.5 D GH1) were mounted vertically in self-cured acrylic blocks. Full metal Ni-Cr copings with a loop on the top were fabricated with appropriate marginal adaptation for each abutment. All samples were divided into 3 groups: first group (MPS) was sandblasted with 50 µm Al2O3 micro ABAP, second group (NSP) was sandblasted with 80 nm Al2O3 nano ABAP, and the third group (C) was assumed as control. The samples were cemented with provisional cement (Temp Bond) and tensile bond strength of cemented copings was evaluated by a universal testing machine after thermic cycling. The t test for independent samples was used for statistical analysis by SPSS software (version 15) at the significant level of 0.05. Final result showed significant difference among all groups (p<0.001) and MPS manifested the highest mean retention (207.88±45.61 N) with significant difference among other groups (p<0.001). The control group showed the lowest bond strength as predicted (48.95±10.44 N). Using nano or micro ABAP is an efficient way for increasing bond strengths significantly, but it seems that micro ABAP was more effective.

scholarly journals Effects of Fluorosis and Self Etching Primers on Shear Bond Strengths of Orthodontic Brackets

2009 ◽  
Vol 03 (03) ◽  
pp. 173-177 ◽  
Author(s):  
Ahmet Yalcin Gungor ◽  
Hakan Turkkahraman ◽  
Necdet Adanir ◽  
Huseyin Alkis
Keyword(s):  
Bond Strength ◽  
Testing Machine ◽  
Orthodontic Brackets ◽  
Universal Testing ◽  
Adhesive Remnant Index ◽  
Halogen Light ◽  
Significant Difference ◽  
Bond Strengths ◽  
Group Ii ◽  
Clinical Changes

ABSTRACTObjectives: To evaluate the effects fluorosis and self etching primers (SEP) on shear bond strengths (SBS) of orthodontic brackets.Methods: A total of 48 (24 fluorosed and 24 non-fluorosed) non-carious freshly extracted human permanent premolar teeth were used in this study. Fluorosed teeth were selected according to the modified Thylstrup and Fejerskov index (TFI), which is based on the clinical changes in fluorosed teeth. Fluorosed and non-fluorosed teeth were randomly assigned to 4 groups of 12 each. In groups I (non-fluorosed teeth) and II (fluorosed teeth), standard etching protocol was used and brackets were bonded with Light Bond. In groups III (non-fluorosed teeth) and IV (fluorosed teeth), Transbond Plus SEP was used and brackets were bonded with Transbond XT Light Cure Adhesive. All specimens were cured with a halogen light. After bonding, SBS of the brackets were tested with Universal testing machine. After debonding, all teeth and brackets in the test groups were examined under 10x magnifications. Any adhesive remained after debonding was assessed and scored according to the modified Adhesive Remnant Index (ARI).Results: ANOVA indicated a significant difference between groups (P<.001). SBS in group II (Light Bond+Fluorosis) were significantly lower than other groups. ARI scores of the groups were also significantly different (P<.001). There was a greater frequency of ARI scores of 1,2 and 3 in group II (Light Bond+Fluorosis).Conclusions: When standard etching protocol was used enamel fluorosis significantly decreased the bond strength of orthodontic brackets. Satisfactory bond strengths were obtained when SEP was used for bonding brackets to the fluorosed teeth. (Eur J Dent 2009;3:173-177)

scholarly journals Compressive and diametral tensile strength of glass ionomer cements

2004 ◽  
Vol 12 (4) ◽  
pp. 344-348 ◽  
Author(s):  
Eduardo Bresciani ◽  
Terezinha de Jesus Esteves Barata ◽  
Ticiane Cestari Fagundes ◽  
Akimi Adachi ◽  
Marina Martins Terrin ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Testing Machine ◽  
Glass Ionomer Cement ◽  
Mean Value ◽  
Atraumatic Restorative Treatment ◽  
Glass Ionomer ◽  
Restorative Treatment ◽  
Significant Difference ◽  
The Mean ◽  
Diametral Tensile Strength

The aim of this study was to compare, in different periods of time, the compressive and diametral tensile strength of a traditional high viscous glass ionomer cement: Fuji IX (GC Corporation), with two new Brazilian GIC's: Vitro-Molar (DFL) and Bioglass R (Biodinamica), all indicated for the Atraumatic Restorative Treatment (ART) technique. Fifteen disk specimens (6.0mm diameter x 3.0mm height) for the diametral tensile strength (DTS) test and fifteen cylindrical specimens (6.0mm diameter x 12.0mm height) for the compressive strength (CS) test were made of each GIC. Specimens were stored in deionized water at 37º C and 100% of humidity in a stove until testing. Five specimens of each GIC were submitted to CS and DTS test in each period, namely 1 hour, 24 hours and 7 days. The specimens were tested in a testing machine (Emic) at a crosshead speed of 1.0mm/min for CS and 0.5mm/min for the DTS test until failure occurred. The data were submitted to two-way ANOVA and Tukey tests (alpha=0.05). The mean CS values ranged from 42.03 to 155.47MPa and means DTS from 5.54 to 13.72 MPa, with test periods from 1h to 7 days. The CS and DTS tests showed no statistically significant difference between Fuji IX and Vitro Molar, except for CS test at 1-hour period. Bioglass R had lowest mean value for CS of the cements tested. In DTS test Bioglass R presented no statistically significant differences when compared with all others tested GICs at 1-hour period and Bioglass R presented no difference at 24-hour and 7-day periods when compared to Vitro-Molar. Further studies to investigate other physical properties such as fracture toughness and wear resistance, as well as chemical composition and biocompatibility, are now needed to better understand the properties of these new Brazilian GIC's.

scholarly journals Load-Application Devices: A Comparative Strain Gauge Analysis

2015 ◽  
Vol 26 (3) ◽  
pp. 258-262 ◽  
Author(s):  
Renato Sussumu Nishioka ◽  
Luis Gustavo Oliveira de Vasconcellos ◽  
Renata Pilli Jóias ◽  
Sigmar de Mello Rode
Keyword(s):  
Strain Gauge ◽  
Repeated Measures ◽  
Testing Machine ◽  
Acrylic Resin ◽  
Load Application ◽  
Chromium Alloy ◽  
Axial Loads ◽  
Nickel Chromium ◽  
Universal Testing ◽  
Significant Difference

In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukey's test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM.

scholarly journals Frictional Characteristics of the Newer Low-friction Elastomeric Ligatures

2016 ◽  
Vol 6 (1) ◽  
pp. 19-23
Author(s):  
Amol Mhatre ◽  
VK Ravindranath ◽  
Sachin Doshi ◽  
Girish Karandikar ◽  
PS Vivek
Keyword(s):  
Testing Machine ◽  
Frictional Resistance ◽  
Minimal Amount ◽  
New Delhi ◽  
Low Friction ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
New Generation

ABSTRACT Aim The aim of this in vitro study was to investigate the efficiency of the new generation of elastomeric ligatures with innovative designs (SlideTM and AlastiKTM Easy-to-Tie) in reducing frictional resistance (FR) during sliding mechanics as compared with conventional ligatures. Materials and Methods Sixty ligature samples divided into four groups were used for the study. Group A: QuiK-StiK™ (3M Unitek, Monrovia, CA, USA), Group B: AlastiK™ Easy-to-Tie (3M Unitek, Monrovia, CA, USA), Group C: Slide™ (Leone, Firenze, Italy), and Group D: SS ligatures 0.010” (Libral Traders, New Delhi, India). Universal Testing Machine, Instron was used for measuring FR at the bracket-wire interface. Results There was statistically significant difference in FR among all the four groups of ligatures tested (p < 0.001). Slide ligatures produced the least amount of FR followed by SS ligatures, Easy-to-Tie, and QuiK-StiK in the increasing order of the FR values registered. Conclusion SlideTM ligatures may represent a valid alternative to passive self-ligating brackets when minimal amount of friction is desired. Angulation introduced into the elastomeric ligatures reduces the friction in comparison to conventional elastomeric ligatures. How to cite this article Vivek PS, Ravindranath VK, Karandikar G, Doshi S, Mhatre A, Sonawane M. Frictional Characteristics of the Newer Low-friction Elastomeric Ligatures. J Contemp Dent 2016;6(1):19-23.

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