scholarly journals Similar biomechanical properties of four tripled tendon graft models for ACL reconstruction

2021 ◽  
Author(s):  
Davide Pavan ◽  
Federica Morello ◽  
Francesco Monachino ◽  
Giuseppe Rovere ◽  
Lawrence Camarda ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Testing Machine ◽  
Thermoelastic Stress ◽  
Fatigue Loading ◽  
Biomechanical Properties ◽  
Simultaneous Increase ◽  
Full Field ◽  
Biomechanical Behavior ◽  
Significant Difference ◽  
Group 2

Abstract Purpose The present study tested and compared the biomechanical properties of four different triplicate graft tendon techniques. Methods 32 tripled tendons from the common extensor muscle of bovine fingers were tested on a material testing machine, passing the end loop over a metal rod of a clevis connected to the load cell on the upper side, and fixing the lower end to a clamp. The samples were divided into four groups: (A) tripled with a free end sutured only to one of the two fixed bundles (B) tripled with a free end positioned between the two fixed strands and sutured to both (C) tripled with an S-shape and all the three strands sutured together at the upper and lower extremities of the graft (D) partially quadrupled with the free end sutured together with the other three bundles at the upper extremity. Each sample was pretensioned at 50 N for 10 min and then subjected to 1000 load control cycles between 50 and 250 N. Finally, each sample was subjected to a load to failure test. Authors also present some preliminary results on the feasibility of a non-contact and full-field Thermoelastic Stress Analysis technique, based on Infrared Thermography, to evaluate the level of stress on the whole graft, and hence on each strand, during fatigue loading. Results Eighty five percent of the samples failed at the level of the clamp. The cyclical elongation progressively decreased in all the samples and there was a simultaneous increase in stiffness. An increased stiffness was noted between Group 2 vs Group 3 and Group 2 vs Group 4 at the 500th and 1000th cycle. The failure loads were as follows: (a) 569.10 N, (b) 632.28 N, (c) 571.68 N, (d) 616.95 N. None of the parameters showed a statistically significant difference between the four groups. Conclusion This study reported similar biomechanical behavior of four different models of tripled grafts suitable for ACL reconstruction. In addition, the biomechanics of overall tripled tendon grafts seems more affected by the viscoelastic property of the tendon itself rather than the preparation method.

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 Lag-Screw Osteosynthesis in Thoracolumbar Pincer Fractures

2020 ◽  
pp. 219256822094144
Author(s):  
Marc Auerswald ◽  
Philipp Messer-Hannemann ◽  
Kay Sellenschloh ◽  
Jan Wahlefeld ◽  
Klaus Püschel ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Testing Machine ◽  
Axial Loading ◽  
Fatigue Loading ◽  
Biomechanical Properties ◽  
Hydraulic Testing ◽  
Ct Scans ◽  
Follower Load ◽  
Lateral Bending ◽  
Bony Healing

Study Design: Biomechanical. Objective: This study evaluates the biomechanical properties of lag-screws used in vertebral pincer fractures at the thoracolumbar junction. Methods: Pincer fractures were created in 18 bisegmental human specimens. The specimens were assigned to three groups depending on their treatment perspective, either bolted, with the thread positioned in the cortical or cancellous bone, or control. The specimens were mounted in a servo-hydraulic testing machine and loaded with a 500 N follower load. They were consecutively tested in 3 different conditions: intact, fractured, and bolted/control. For each condition 10 cycles in extension/flexion, torsion, and lateral bending were applied. After each tested condition, a computed tomography (CT) scan was performed. Finally, an extension/flexion fatigue loading was applied to all specimens. Results: Biomechanical results revealed a nonsignificant increase in stiffness in extension/flexion of the fractured specimens compared with the intact ones. For lateral bending and torsion, the stiffness was significantly lower. Compared with the fractured specimens, no changes in stiffness due to bolting were discovered. CT scans showed an increasing fracture gap during axial loading both in extension/flexion, torsion, and lateral bending in the control specimens. In bolted specimens, the anterior fragment was approximated, and the fracture gap nullified. This refers to both the cortical and the cancellous thread positions. Conclusion: The results of this study concerning the effect of lag-screws on pincer fractures appear promising. Though there was little effect on stiffness, CT scans reveal a bony contact in the bolted specimens, which is a requirement for bony healing.

scholarly journals Effect of cement type and thickness on push-out bond strength of fiber posts

2018 ◽  
Vol 12 (4) ◽  
pp. 277-282
Author(s):  
Farzaneh Farid ◽  
Khadijeh Rostami ◽  
Sareh Habibzadeh ◽  
MohammadJavad Kharazifard
Keyword(s):  
Bond Strength ◽  
Testing Machine ◽  
Test Results ◽  
Resin Cements ◽  
Fiber Posts ◽  
Significant Difference ◽  
Root Dentin ◽  
Group 2 ◽  
Self Etch ◽  
Push Out

Background. This study investigated the effect of the thickness of two resin cements on push-out bond strength of fiber posts to root dentin. Methods. Sixty decoronated single-rooted teeth were endodontically treated. The specimens were then randomly allocated to two groups (n=30); group 1: drill size 90 w, matching the size of fiber posts used; group 2: drill size 110, larger than the posts. The specimens in each group were divided into 2 subgroups (n=15); subgroup SE, in which the posts were cemented with self-etch Panavia F2.0 and subgroup SA, in which self-adhesive Panavia cement was used. After 72 hours, 2 slices with 1 mm of thickness were prepared from the mid-root of each specimen. Push-out bond strength test was performed in a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and t-test. Results. The mean bond strengths of the posts cemented in matched-size spaces for SE and SA groups were 4.02±1.6 and 4.12±2.3 MPa, respectively. For posts cemented in oversized spaces, the values were 4.9±2.3 and 2.8±1.3 MPa, respectively. In matched-size spaces, there was no significant difference between the two groups. Conclusion. The results of this study suggested that increasing the cement thickness would reduce the bond strength of fiber posts to root dentin when self-adhesive cements are used; however, self-etch adhesives were not affected.

Biomechanical properties of expander compared with conventional screws

2002 ◽  
Vol 97 (3) ◽  
pp. 346-349 ◽  
Author(s):  
Aziz Rassi-Neto ◽  
Antonio Shimano
Keyword(s):  
Maximum Load ◽  
Biomechanical Properties ◽  
Biomechanical Study ◽  
Intergroup Difference ◽  
Content Type ◽  
Significant Difference ◽  
Group 2 ◽  
The Comparative Study ◽  
Screw Group ◽  
Fine Print

Object. A pullout strength biomechanical study was performed in 20 fresh swine vertebral bodies in which titanium expander (Group 1) and conventional screws (Group 2) were placed. Methods. The screws were inserted into the anterosuperior portion of the anterior spine, and assessment was performed after application of loads. The expander screw is composed of two parts: 1) a cover with an external portion comprising tight thin threads; and 2) a compact internal screw inserted through the cover that allows expansion. In the comparative study between the screws in Groups 1 and 2 maximum load was assessed, and the intergroup difference was significant (p = 0.00001 [t-test]); regarding load at the elasticity threshold, a significant difference was also observed (p = 0.0063). With regard to rigidity (stiffness), there was a tendency in both groups toward significance (p = 0.069). With regard to absorbed energy in the elastic phase, statistical analysis showed a significant intergroup difference (p = 0.00439). The expander screw showed a greater load-bearing capacity than the conventional screw. Adhesion to bone in relation to the applied load and displacement was greater (significant tendency) in the expander screw group than in the conventional screw group. Conclusions. The expander screws exhibited a greater capacity to absorb energy in the elastic phase. They adhered better to bone, were easy to insert, and, if necessary, were simple to remove.

scholarly journals Biomechanical Properties of the Bone During Implant Placement

2020 ◽  
Author(s):  
Adam Laszlo Nagy ◽  
Nándor Tamás Práger ◽  
Zsolt Tóth ◽  
Tamás Tarjányi ◽  
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 Introduction: In our research we examined the biomechanical properties of a bone model. Porcine ribs are used as experimental model. Our objective is 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 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.Conclusions: 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, and if even one implant is lost at the implant site during All-On-Four protocol the stabilizing effect of the implants cannot be expected.

scholarly journals Fracture Resistance of a Bulk-Fill and a Conventional Composite and a Combination of Both for Coronal Restoration of Severely Damaged Primary Anterior Teeth

2019 ◽  
Author(s):  
Shahram Mosharrafian ◽  
Maryam Shafizadeh ◽  
Zeinab Sharifi
Keyword(s):  
Fracture Resistance ◽  
Treatment Time ◽  
Testing Machine ◽  
Anterior Teeth ◽  
Significant Difference ◽  
Group 3 ◽  
The Mean ◽  
Group 2 ◽  
One Way Anova

Objectives: This study aimed to compare the fracture resistance of a bulk-fill and a conventional composite and a combination of both for coronal restoration of severely damaged primary anterior teeth. Materials and Methods: In this in vitro experimental study, 45 primary anterior teeth were randomly divided into three groups. After root canal preparation, the canals were filled with Metapex paste such that after the application of 1 mm of light-cure liner, 3 mm of the coronal third of the canal remained empty for composite post fabrication. Filtek Z250 conventional composite was used in group 1, Sonic-Fill bulk-fill composite was used in group 2 and Sonic-Fill with one layer of Filtek Z250 as the veneering were used in group 3. Adper Single Bond 2 was used in all groups. The teeth were thermocycled, and fracture resistance was measured by a universal testing machine. The mode of fracture was categorized as repairable or irreparable. Data were analyzed using one-way ANOVA. Results: The mean fracture resistance was 307.00±74.72, 323.31±84.28 and 333.30±63.96 N in groups 1 to 3, respectively (P=0.55). The mean fracture strength was 14.53±2.98, 15.08±2.82 and 15.26±3.02 MPa in groups 1 to 3, respectively (P=0.77). The frequency of repairable mode of failure was 80% for the conventional, 73.6% for the bulk-fill and 80% for the bulk-fill plus conventional group, with no significant difference (P>0.05). Conclusions: Bulk-fill composites can be used for coronal reconstruction of severely damaged primary anterior teeth similar to conventional composites to decrease the treatment time in pediatric patients.

Comparative Study of Biomechanical Properties between Needled Suture and Needleless Suture in Multi-Strand Tendon Graft Model

2021 ◽  
Vol 104 (9) ◽  
pp. 1447-1451
Keyword(s):  
Testing Machine ◽  
Biomechanical Properties ◽  
Tendon Graft ◽  
Suture Technique ◽  
Biomechanical Study ◽  
Modes Of Failure ◽  
Tendon Elongation ◽  
Significant Difference ◽  
Load To Failure ◽  
Distraction Force

Objective: To compare the biomechanical properties of the Chinese finger (CF) suture, a needleless suture technique, with the baseball stitch (BS) suture, a needled suture technique, in a multi-strand model by using a 4-strand tendon model. Additionally, the BS was compared with the serial rolling hitch (RH), a locking needleless suture technique. Materials and Methods: 4-strand grafts, made from two 20-cm fresh porcine toe extensors, were used in all three groups. After the grafts were sutured, pretension was applied with a load of 100-N distraction force for five minutes. After the tendon elongation was measured before and after the pretension, the distraction force was continued until the constructed graft failed. Stress-strain relationship graphs were recorded by universal testing machine (UTM), distributing to the calculation of percentage on tendon elongation, stiffness, and load-to-failure. Results: The BS had significantly higher load of failure than the CF (p=0.001) but no significant difference when compared with the RH. Comparing between BS, CF, and RH, there were no significant difference in stiffness and percentage of tendon elongation. In modes of failure, there was evidence of knot slipping in CF in six of six cases and graft strangulation in RH in four of six cases. Conclusion: Multi-strand model BS, a needled suture, had a higher load to failure than CF, a needleless suture. Moreover, needleless sutures had serious modes of failure, which were knot slipping and strangulation of graft by the suture material. Therefore, needleless suture technique for multi-strand tendon graft preparation was not recommended. Keywords: Tendon preparation; Multi-Strand; Needled suture; Needleless suture; Chinese finger; Baseball stitch; Rolling Hitch; Biomechanical study; Graft elongation; Load to failure

scholarly journals Exposure of Biomimetic Composite Materials to Acidic Challenges: Influence on Flexural Resistance and Elastic Modulus

Biomimetics ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 56
Author(s):  
Andrea Scribante ◽  
Simone Gallo ◽  
Stefano Scarantino ◽  
Alberto Dagna ◽  
Claudio Poggio ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Composite Materials ◽  
Flexural Strength ◽  
Testing Machine ◽  
Distilled Water ◽  
Group 4 ◽  
Significant Difference ◽  
Group 5 ◽  
Group 2 ◽  
Flexural Resistance

Acidic conditions of the oral cavity, including soft drinks and cariogenic bacteria, represent a damage for restorative biomimetic composite materials. The aim of this study is to assess the influence of two different acidic challenges on the flexural strength and elastic modulus of five composites: x-tra fil (Group 1, XTF), GrandioSO x-tra (Group 2, GXT), Admira Fusion x-tra (Group 3, AFX), VisCalor bulk (Group 4, VCB), and Enamel Plus HRi (Group 5, EPH). Thirty samples for each group were randomly divided and assigned to three different treatments: storage in distilled water as the controls (subgroups 1a–5a), 3 weeks distilled water + 1 week Coca-Cola (subgroups 1b-5b), and 4 weeks Coca-Cola (subgroups 1c–5c). For each subgroup, the flexural strength and elastic modulus were measured using an Instron universal testing machine, and data were submitted to statistical analysis. Considering subgroups B, no material showed a significant difference in the flexural strength with the controls (p > 0.05), whereas for subgroups C, only GXT and VCB showed significantly lower values (p < 0.05). AFX reported the lowest flexural strength among the materials tested. As regards the elastic modulus, no material showed a significant variation after acidic storages when compared with the respective control (p > 0.05). AFX and EPH reported the lowest elastic modulus compared to the other materials. All composites tested showed adequate flexural properties according to the standards, except for AFX. This biomimetic material, along with EPH, might be indicated for V class (cervical) restorations considering the lowest values of elasticity reported.

scholarly journals Effect of Different Time Periods of Vital Bleaching on Flexural Strength of Bovine Enamel and Dentin Complex

2007 ◽  
Vol 8 (3) ◽  
pp. 21-28 ◽  
Author(s):  
Marjaneh Ghavamnasiri ◽  
Sara Abedini LNU ◽  
Alireza Mahdizadeh Tazangi
Keyword(s):  
Flexural Strength ◽  
Artificial Saliva ◽  
Testing Machine ◽  
Control Group ◽  
Mean Values ◽  
Significant Difference ◽  
Time Periods ◽  
Group 2 ◽  
Bovine Enamel

Abstract Aim The aim of this in vitro study was to evaluate the effect of 20% carbamide peroxide (CP) on the flexural strength (FS) of bovine enamel and dentin complex. Methods and Materials One hundred sound bovine teeth were selected for use. Blocks (2×3×8 mm) from the middle portion of the facial surfaces of each crown were sectioned from the teeth. The specimens were randomly divided into five groups (n=20) based on the time period of vital bleaching. Group 1 comprised the control group kept in artificial saliva. The experimental groups subjected to immersion in 20% CP, Opalescence, for four, six and eight weeks, respectively (eight hours daily). Mechanical testing was performed 24 hours after the last treatment using an Instron Universal Testing Machine with a crosshead speed of 0.5 mm/min. The results were analyzed by one-way analysis of variance (ANOVA) and Tukey's test (α=0.05). Results Mean values for FS were 141.27, 103.06, 120.71, 130.23, and 117.90 (Mpa), respectively. Statistically significant differences in FS were noted among the groups. A statistically significant difference was observed between Group 2 (two week bleach) and the control. Conclusion Application of 20% CP bleach for two weeks provided significant decreases in FS of bovine enamel and dentin complex. Similar decreases were not observed among the other groups. Citation Ghavamnasiri M, Abedini S, Tazangi AM. Effect of Different Time Periods of Vital Bleaching on Flexural Strength of Bovine Enamel and Dentin Complex. J Contemp Dent Pract 2007 March;(8)3:021-028.

scholarly journals Bond Strength of Amorphous Calcium Phosphate–Containing Orthodontic Composite Used as a Lingual Retainer Adhesive

2009 ◽  
Vol 79 (1) ◽  
pp. 117-121 ◽  
Author(s):  
Tancan Uysal ◽  
Mustafa Ulker ◽  
Gulsen Akdogan ◽  
Sabri Ilhan Ramoglu ◽  
Esra Yilmaz
Keyword(s):  
Calcium Phosphate ◽  
Bond Strength ◽  
Amorphous Calcium Phosphate ◽  
Testing Machine ◽  
Internal Diameter ◽  
Compression Load ◽  
Significant Difference ◽  
Group 2 ◽  
Lingual Retainer ◽  
Group 1

Abstract Objective: To evaluate the shear bond strength and fracture mode difference between amorphous calcium phosphate (ACP)–containing adhesive and conventional resin-based composite material used as an orthodontic lingual retainer adhesive. Materials and Methods: Forty crowns of extracted lower human incisors were mounted in acrylic resin, leaving the buccal surface of the crowns parallel to the base of the molds. The teeth were randomly divided into two groups: experimental and control, containing 20 teeth each. Conventional lingual retainer composite (Transbond-LR, 3M-Unitek) and ACP-containing orthodontic adhesive (Aegis-Ortho) were applied to the teeth surface by packing the material into the cylindrical plastic matrices with a 2.34-mm internal diameter and a 3-mm height (Ultradent) to simulate the lingual retainer bonding. For shear bond testing, the specimens were mounted in a universal testing machine, and an apparatus (Ultradent) attached to a compression load cell was applied to each specimen until failure occurred. The shear bond data were analyzed using Student's t-test. Fracture modes were analyzed by χ2 test. Results: The statistical test showed that the bond strengths of group 1 (control Transbond-LR, mean: 24.77 ± 9.25 MPa) and group 2 (ACP-containing adhesive, mean: 8.49 ± 2.53 MPa) were significantly different from each other. In general, a greater percentage of the fractures were adhesive at the tooth-composite interface (60% in group 1 and 55% in group 2), and no statistically significant difference was found between groups. Conclusion: The ACP-containing Aegis-Ortho adhesive resulted in a significant decrease in bond strength to the etched enamel surface.

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