scholarly journals Protective/restorative role of the adipose tissue-derived mesenchymal stem cells on the radioiodine-induced salivary gland damage in rats

2017 ◽  
Vol 51 (3) ◽  
pp. 307-316 ◽  
Author(s):  
Güleser Saylam ◽  
Ömer Bayır ◽  
Salih Sinan Gültekin ◽  
Ferda Alparslan Pınarlı ◽  
Ünsal Han ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Adipose Tissue ◽  
Salivary Gland ◽  
Study Groups ◽  
Significant Deterioration ◽  
Group 6 ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

AbstractBackgroundTo analyze protective/regenerative effects of adipose tissue-derived mesenchymal stem cells (ADMSC) on131I-Radioiodine (RAI)-induced salivary gland damage in rats.Materials and MethodsStudy population consisted of controls (n:6) and study groups (n:54): RAI (Group 1), ADMSC (Group 2), amifostine (Group 3), RAI+amifostine (Group 4), concomitant RAI+ADMSC (Group 5) and RAI+ADMSC after 48 h (Group 6). We used light microscopy (LM), transmission electron microscopy (TEM), and salivary gland scintigraphy (SGS), and analyzed data statistically.ResultsWe observed the homing of ADMSC in salivary glands at 1stmonth on LM. RAI exposure affected necrosis, periductal fibrosis, periductal sclerosis, vascular sclerosis and the total sum score were in a statistically significant manner (P< 0.05). Intragroup comparisons with LM at 1stand 6thmonths revealed statistically significant improvements in Group 6 (P< 0.05) but not in Groups 4 and 5. Intergroup comparisons of the total score showed that Groups 4 and 5 in 1stmonth and Group 6 in 6thmonth had the lowest values. TEM showed vacuolization, edema, and fibrosis at 1stmonth, and an improvement in damage in 6thmonth in Groups 5 and 6. SGSs revealed significant differences for the maximum secretion ratio (Smax) (P= 0.01) and the gland-to-background ratio at a maximum count (G/BGmax) (P= 0. 01) at 1stmonth, for G/BGmax (P= 0.01), Smax (P= 0.01) and the time to reach the maximum count ratio over the time to reach the minimum count (Tmax/Tmin) (P= 0.03) at 6thmonth. 1stand 6thmonth scans showed differences for Smax and G/BGmax (P= 0.04), but not for Tmax/Tmin (p> 0.05). We observed a significant deterioration in gland function in group 1, whereas, mild to moderate deteriorations were seen in protective treatment groups.ConclusionsOur results indicated that ADMSC might play a promising role as a protective/regenerative agent against RAI-induced salivary gland dysfunction.

scholarly journals Synergic Effect of Combined Therapy of Hyperbaric Oxygen and Adipose-derived Mesenchymal Stem Cells on Improving Neurological Function After Acute Traumatic Spinal Cord Injury in Rat

2021 ◽  
Author(s):  
Tsung-Cheng Yin ◽  
Pei-Lin Shao ◽  
Kuan-Hung Chen ◽  
Kun-Chen Lin ◽  
John Y. Chiang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Stem Cells ◽  
Spinal Cord Injury ◽  
Mesenchymal Stem Cells ◽  
Traumatic Spinal Cord Injury ◽  
Voltage Gated ◽  
Cord Injury ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

Abstract Background: This study tested whether combined hyperbaric oxygen (HBO) and allogenic adipose-derived mesenchymal stem cells (ADMSCs) would be superior to either one for improving the neurological function in rat after acute traumatic spinal cord injury (TSCI) in rat. Methods and Results: Adult-male SD rats (n=40) were equally categorized into group 1 (sham-operated control), group 2 (TSCI), group 3 (TSCI + HBO for 1.5h/day for 14 consecutive days after TSCI), group 4 (TSCI + ADMSCs/1.2x106 cells by intravenous injection at 3h and days 1/2 after TSCI) and group 5 (TSCI + HBO + ADMSCs), euthanized and spinal-cord tissue was harvested by day 49 after TSCI. The result showed that the protein expressions of oxidative-stress (NOX-1/NOX-2), inflammatory-signaling (TLR-4/MyD88/IL-1ß/TNF-α/substance-p), cell-stress signaling (PI3K/p-AKT/p-mTOR) and the voltage gated sodium channel (Nav1.3/1.8/1.9) biomarkers were highest in group 2, lowest in group 1 and significantly lower in group 5 than in groups 3/4 (all p<0.0001), but they did not differ between groups 3/4. The spinal cord-damaged area, the cellular levels of inflammatory/DNA-damaged (CD68+/GFAP+/γ-H2AX+ cells), MAPK family biomarkers (p-P38/p-JNK/p-ERK1/2) and cellular expressions of voltage gated sodium channel (Nav.1.3, Nav.1.8 and Nav.1.9 in NF200+ cells) as well as the pain facilitated cellular expressions (p-P38+/peripherin+ cells, p-JNK+/peripherin+ cells, p-ERK/NF200+ cells) exhibited an identical pattern of inflammation, whereas the neurological integrity displayed an opposite pattern of inflammation among the groups (all p<0.0001). Conclusion: Combined HBO-ADMSCs therapy offered additional benefits for protecting the neurological architectural and functional integrity against acute TSCI.

scholarly journals Combined melatonin-adipose derived mesenchymal stem cells therapy effectively protected the testis from testicular torsion-induced ischemia-reperfusion injury

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yen-Ta Chen ◽  
Fei-Chi Chuang ◽  
Chih-Chao Yang ◽  
John Y. Chiang ◽  
Pei-Hsun Sung ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Testicular Torsion ◽  
Ischemia Reperfusion ◽  
Opposite Pattern ◽  
Protein Expressions ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

Abstract Background This study tested the hypothesis that combined melatonin (Mel) and adipose-derived mesenchymal stem cells (ADMSCs) treatment was superior to either one alone on protecting the testis against acute testicular torsion-induced ischemia-reperfusion (TTIR) injury. Methods and results Male adult SD rats (n = 30) were equally categorized into group 1 (sham-operated control), group 2 [TTIR/by torsion of right/left testis (i.e., ischemia) with rotated 720° counterclockwise for 2 h, then detorsion (i.e., reperfusion) to the original position for 72 h], group 3 (TTIR + Mel/intraperitoneal administration/50 mg/kg at 30 min after ischemia, followed by 20 mg at 3 h and days 1/2/3 after TTIR), group 4 (TTIR + ADMSCs/1.2 × 106 cells/by tail-vein administration at 30 min after ischemia, followed by days 1/2 TTIR), and group 5 (TTIR + Mel + ADMSCs/tail-vein administration). The result showed that the protein expressions of oxidative-stress (NOX-1/NOX-2/oxidized-protein), apoptotic/mitochondrial-damaged (mitochondrial-Bax/cleaved-caspase3/cleaved-PARP/cytosolic-cytochrome C), and fibrotic (TGF-ß/Smad3) biomarkers as well as testicular damage scores were lowest in group 1, highest in group 2, and significantly higher in groups 3/4 than in group 5, but they showed no difference between groups 3/4, whereas the protein expressions of androgen receptor (AR) and vimentin showed an opposite pattern of oxidative stress (all p < 0.0001). The cellular levels of inflammation (MMP-9/MPO/CD68) exhibited an identical pattern, whereas the numbers of Sertoli cells, α-tubulin, AR and vimentin as well as thickness of seminiferous tubule exhibited an opposite pattern of oxidative stress among the groups (all p < 0.0001). Conclusion Mel-ADMSCs effectively protected the testis against TTIR injury.

scholarly journals Association between serum oestradiol level on the hCG administration day and neonatal birthweight after IVF-ET among 3659 singleton live births

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Liu ◽  
Jing Li ◽  
Wanyu Zhang ◽  
Yihong Guo
Keyword(s):  
Birth Weight ◽  
Ovarian Stimulation ◽  
Group 4 ◽  
Group 6 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
The Impact ◽  
Ivf Et ◽  
Group 1

AbstractOestradiol, an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization-embryo transfer (IVF-ET) cycles. A supraphysiologic E2 level is inevitable during controlled ovarian hyper-stimulation (COH), and its effect on the outcome of IVF-ET is controversial. The aim of this retrospective study is to evaluate the association between elevated serum oestradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and neonatal birthweight after IVF-ET cycles. The data of 3659 infertile patients with fresh IVF-ET cycles were analysed retrospectively between August 2009 and February 2017 in First Hospital of Zhengzhou University. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E2 levels ≤ 1000 pg/mL, n = 230), group 2 (serum E2 levels between 1001 and 2000 pg/mL, n = 524), group 3 (serum E2 levels between 2001 and 3000 pg/mL, n = 783), group 4 (serum E2 levels between 3001 and 4000 pg/mL, n = 721), group 5 (serum E2 levels between 4001 and 5000 pg/mL, n = 548 ), and group 6 (serum E2 levels > 5000 pg/mL, n = 852). Univariate linear regression was used to evaluate the independent correlation between each factor and outcome index. Multiple logistic regression was used to adjust for confounding factors. The LBW rates were as follows: 3.0% (group 1), 2.9% (group 2), 1.9% (group 3), 2.9% (group 4), 2.9% (group 5), and 2.0% (group 6) (P = 0.629), respectively. There were no statistically significant differences in the incidences of neonatal LBW among the six groups. We did not detect an association between peak serum E2 level during ovarian stimulation and neonatal birthweight after IVF-ET. The results of this retrospective cohort study showed that serum E2 peak levels during ovarian stimulation were not associated with birth weight during IVF cycles. In addition, no association was found between higher E2 levels and increased LBW risk. Our observations suggest that the hyper-oestrogenic milieu during COS does not seem to have adverse effects on the birthweight of offspring after IVF. Although this study provides some reference, the obstetric-related factors were not included due to historical reasons. The impact of the high estrogen environment during COS on the birth weight of IVF offspring still needs future research.

EFFECT OF TREATMENT WITH STREPTOKINASE AND HEPARIN ON FIBRINOGEN, FIBRIN AND RELATED PROTEINS IN ACUIE MYOCARDIAL INFARCTION (/ME) PATIENTS

1987 ◽  
Author(s):  
V Vila ◽  
E Reganon ◽  
J Aznar ◽  
V Lacueva ◽  
M Ruano
Keyword(s):  
Degradation Products ◽  
Heparin Therapy ◽  
Heparin Group ◽  
Normal Value ◽  
Group 4 ◽  
Group 6 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

The properties of fibrinogen and fibrin, the levels of fibrincpeptide A (FPA) and fibrin(ogen) degradation products (FDP) were studied in 34 patients with AMI who were undergoing thrombolytic and heparin therapy. They were classified into 6 groups accordingto their stage of treatment: group 1, before intravenous administration of 800.000 U streptokinase over 30 min; group 2, after a<Mnistraticn of SK but before adninistraticn of heparin; group 3, during 24 h ofthe 5 ng/h heparin continuous infusion; group 4, during 48-72 h of the 16.6 ng/h heparin continuous infhsion; group 5, after 1 week of administration of SK and with a bolus inyection of 50 rg heparin every 4 h; group 6, patients who were undergoing only heparin treatment. The Fg 1/ Fg II ratio varies during treatment with SK and heparin. In group 1 a sligjnt increase (2.5) is observed. Group 2 shows a significantdecrease (0.6) as a result of fibrinolysis. In group3 the ratio reaches normal value (1.8) while in the fourth group it is twice the normal value (4). The value for group 5 is nearly normal (2.1), and in group 6 it reaches values similar to those obtained in group 4, which implies that the rise in the Fgl/Fgll ratio is not a result of fibrinolytic treatment. TheFPA level shows and increase in patients with AMI (group 1,126 ng/ml). When SK treatment is applied (group 2), FPA decreases to 52 ng/ml. Later treatment with heparin (group-3, 82; group-4, 44 and group-5, 81ng/ml) does not neutralize thrcmbinic activity. Patients treated only with heparin (group 6) show an FPAvalue of 19 ng/ml, which is lower than in the other groups. All of this indicates that thrombin is activated after fibrinolytic treatment. FDP values show asignificant increase in the six groups (1, 53; 2, 430; 3, 128; 4, 270; 5, 139 and 6, 141 ug/ml), which indicates that during treatment with heparin the fibrinolytic activity persists. he formation of highly cross-linked fibrin is altered in groups 1,2,3 and 4,as a consequence of circulating FDP effect and fibrincgeno- lysis.The permeability of the fibrin clotdecreases in groups 1 (0.42), 2 (1.3), 4 (1.1) and 5(0.5 ml/s/ng) and increases in group 2 (23.2 ml/s/nig) with respect to the normal plasma value (3.2 ml/s/nrg). The decrease in permeability must be related to the existence of hypercoagulability resistant to heparinization. FPA values, tine Fgl/Fgll ratio, andfibrin permeability can be used to evaluate the degree of thrcmbin activity during thrombolytic treatmentinAMI.

Estudo de fraturas nos taludes de corte, em rocha vulcânica, ao longo da BR 158, Santa Maria, RS

1999 ◽  
Vol 21 (21) ◽  
pp. 97
Author(s):  
Andrea V. Nummer ◽  
Luis Eduardo S. Robaina ◽  
Marcos Geovane Berger
Keyword(s):  
Conditioning Factors ◽  
Weathering Processes ◽  
Group 4 ◽  
Group 6 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Road Data ◽  
Santa Maria ◽  
Group 1

Weathering processes and jointing degree are the conditioning factors for rock falI.The fractured volcanic lithologies from Santa Maria, RS, Brazil, were studied along the BR 158 road. Data was gathered through the Scanline method from BRADY & BROWN (1985) and analyzed by vector statistics.Six main jointing groups were defined, associated to rock cooling and shrinking. Main attitudes are: Group 1: 348;83; Group 2: 174;82; Group 3: 85;76; Group 4: 265;75; Group 5: 300;42 and Group 6: 121 ;53.

scholarly journals Effect of Aqueous Extract of Tribulus terrestris orally administration on some Biochemical Parameters in Castrated Male Rabbits

2012 ◽  
Vol 36 (2) ◽  
pp. 217-221
Author(s):  
Abeer Uthman Moosa
Keyword(s):  
Aqueous Extract ◽  
Biochemical Parameters ◽  
Iron Concentration ◽  
Iron Phosphate ◽  
Tribulus Terrestris ◽  
Biochemical Tests ◽  
Group 6 ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

The present study is aimed to investigate the influence of an aqueous extract of Tribulus terrestris on some biochemical parameters namely, alkaline phosphatase (ALP), Iron, phosphate (PO4), sodium (Na+), potassium (K+), aldosterone, and cortico steroid in unilateral and bilateral castrated male rabbits. Thirty mature male rabbits which are divided randomly in to six groups. group 1: is control, group2: orally administrated 150 mg / kg / day of an aqueous extract of T. terrestris, group3: is bilateral castrated rabbits received D. W., group4: is bilateral castrated rabbits received (150 mg / kg / day) of the extract, group 5: unilateral castrated rabbits received D. W., group 6 is unilateral castrated rabbits received 150 mg / kg / day of the extract, all doses were given orally every day for 30 days. At the end of the experiment, sera were collected and biochemical tests measured. The results showed a significant (P<0.05) increased in ALP level in group 2 and in PO4 level in group 5 in comparison with group1, while PO4 level tended to be decreased significantly (P<0.05) in group 6 when it compared with group 5. The results also showed a significant(P<0.05) increased in (K+) and (Na+) in group 2 and group 6 in comparison with group1 while there was a significant(P<0.05) decreased in (K+) and (Na+) in group 4 when it compared with group 2. In addition there was a significant (P<0.05) increased in aldosterone concentration in group 6 compared with group 1 and group 2. While there was a significant decreased in cortico steroid concentration in group 3 , 5 and 2 compared with group 1 but the cortico steroid showed a significant (P<0.05) increased in group 6 compared with group 1. There were no significant differences between groups concerning the iron concentration.

Evaluation of the Effect of Different Ferrule Designs on the Fracture Resistance of Endodontically Treated Maxillary Central Incisors Incorporating Fiber Posts, Composite Cores and Crown Restorations

2007 ◽  
Vol 8 (7) ◽  
pp. 62-69 ◽  
Author(s):  
Emre Ozel ◽  
Idil Dikbas ◽  
Jale Tanalp ◽  
Temel Koksal ◽  
Mustafa Ersoy
Keyword(s):  
Fracture Resistance ◽  
Quartz Fiber ◽  
Group 4 ◽  
Fiber Posts ◽  
Significant Difference ◽  
Group 6 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

Abstract Aim The purpose of this study was to evaluate the fracture resistance of endodontically treated maxillary central incisors restored with quartz fiber posts, composite cores, and crowns when different types of ferrule designs were incorporated. Methods and Materials Sixty maxillary incisors were divided into six groups: Group 1 (control): teeth with root canal treatments having a full crown prosthesis; Group 2: teeth with a 2 mm circumferential ferrule; Group 3: teeth with a 2 mm ferrule only in the vestibular region; Group 4: teeth with a 2 mm ferrule only in the palatal region; Group 5: teeth with a 2 mm ferrule in the vestibular and palatal region, having cavities in both proximal areas; and Group 6: teeth with no ferrule. The teeth in the experimental groups were restored with quartz fiber posts-composite cores and full metallic crowns. All experimental teeth were subjected to an increasing compressive force with a crosshead speed of 1 mm/min, until fracture occurred. Results The median fracture values of groups were as follows: Group 1: 574.4 N, Group 2: 472.4 N, Group 3: 474.3 N, Group 4: 480.7 N, Group 5: 463.1 N, and Group 6: 297.9 N. A statistically significant difference was found between Group 1 and Group 6 (p< 0.01). Conclusion It was concluded different ferrule designs did not have any influence on the fracture resistance of teeth with fiber posts. The results of this study indicate fiber posts can safely be used for their reinforcing properties. Furthermore, there is no significant change in the resistance of teeth with fiber posts regardless of which ferrule design is incorporated. The property of these types of posts is an additional advantage in clinical practice. Citation Dikbas I, Tanalp J, Ozel E, Koksal T, Ersoy M. Evaluation of the Effect of Different Ferrule Designs on the Fracture Resistance of Endodontically Treated Maxillary Central Incisors Incorporating Fiber Posts, Composite Cores and Crown Restorations. J Contemp Dent Pract 2007 November; (8)7:062-069.

scholarly journals Correlation between Intraocular Pressure and Thickness of Extraocular Muscles, the Severity and Activity of Thyroid-associated Orbitopathy

Folia Medica ◽  
2019 ◽  
Vol 61 (1) ◽  
pp. 90-96
Author(s):  
Nina Staneva Stoyanova ◽  
Marieta Konareva-Kostianeva ◽  
Vesela Mitkova-Hristova ◽  
Irina Angelova
Keyword(s):  
Intraocular Pressure ◽  
Extraocular Muscles ◽  
Ocular Motility ◽  
Group 4 ◽  
Group 6 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Severity Of The Disease ◽  
Group 1

Abstract Aim: To establish the correlation between intraocular pressure (IOP) and thickness of extraocular muscles (EOM), the severity and activity of thyroid-associated orbitopathy (TAO). Materials and methods: 50 patients with TAO were included in the study. They all underwent a thorough ophthalmic examination, Goldmann tonometry (mm Hg) and computer tomography of the orbits, the muscle thickness sum (MTS) of each eye being measured in millimeters. According to the activity of TAO, the patients were divided into two groups – with and without activity, and according to the severity of the disease – into 6 groups: Group 1 (‘O’) had only subjective symptoms, group 2 (‘S’) had soft tissue symptoms, group 3 (‘P’) – proptosis, group 4 (‘E’) – ocular motility disorders, group 5 (‘C’) – corneal damage, and group 6 (‘Si’) – visual impairment; Results: TAO activity was registered in 21 patients (42 eyes, 42%) with MTS 23.39±3.81 and IOP 18.43±4.16. Twenty-nine patients (58 eyes, 58%) with MTS 19±3.21 and IOP 15.98±4.59 showed no TAO activity. The IOP within the groups, in terms of severity, was as follows: group 1 – 19.92+4.05; group 2 – 14.5±2.55; group 3 – 18.04±4.51; group 4 – 18.2±5.05; group 5 – 20.5±4.5; group 6 – 21.5±4.95. A correlation between the IOP and MTS was found. Conclusions: The IOP in patients with TAO depends on the thickness of the EOM, as well as on the activity and severity of the disease.

scholarly journals Umbilical Cord Blood Mesenchymal Stem Cells as an Infertility Treatment for Chemotherapy Induced Premature Ovarian Insufficiency

Biomedicines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 7 ◽  
Author(s):  
Sara Mohamed ◽  
Shahinaz Shalaby ◽  
Soumia Brakta ◽  
Lelyand Elam ◽  
Amro Elsharoud ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Treatment Group ◽  
Cord Blood ◽  
Umbilical Cord Blood ◽  
Serum Levels ◽  
Ovarian Insufficiency ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Background: Premature ovarian insufficiency (POI) is a challenging disease, with limited treatment options at the moment. Umbilical cord blood mesenchymal stem cells (UCMSCs) have demonstrated promising regenerative abilities in several diseases including POI. Materials and Method: A pre-clinical murine case versus vehicle control randomized study. Two experiments ran in parallel in each of the three groups. The first was to prove the ability of UCMSCs in restoring ovarian functions. The second was to prove improved fertility. A total of 36 mice were randomly assigned; 6 mice into each of 3 groups for two experiments. Group 1 (control), group 2 (sham chemotherapy), group 3 (stem cells). Results: In the first experiment, post-UCMSCs treatment (group 3) showed signs of restored ovarian function in the form of increased ovarian weight and estrogen-dependent organs (liver, uterus), increased follicular number, and a significant decrease in FSH serum levels (p < 0.05) compared to group 2, and anti-Mullerian hormone (AMH) serum levels increased (p < 0.05) in group 3 versus group 2. Immuno-histochemistry analysis demonstrated a higher expression of AMH, follicle stimulating hormone receptor (FSHR) and Inhibin A in the growing follicles of group 3 versus group 2. In the second experiment, post-UCMSCs treatment (group 3) pregnancy rates were higher than group 2, however, they were still lower than group 1. Conclusion: We demonstrated the ability of UCMSCs to restore fertility in female cancer survivors with POI and as another source of stem cells with therapeutic potentials.

scholarly journals Influence of shaft length on torsional behavior of endodontic nickel–titanium instruments

Odontology ◽  
2020 ◽  
Author(s):  
Gianluca Gambarini ◽  
Marco Seracchiani ◽  
Alessio Zanza ◽  
Gabriele Miccoli ◽  
Andrea Del Giudice ◽  
...  
Keyword(s):  
Nickel Titanium ◽  
Related Factor ◽  
Related Factors ◽  
Shaft Length ◽  
Torsional Resistance ◽  
Group 6 ◽  
Group 5 ◽  
Group 2 ◽  
Niti Instruments ◽  
Group 1

AbstractTorsional stresses are one of the most frequent causes of intracanal separation of nickel–titanium endodontic instruments, which represents a great concern of endodontists. For this reason, torsional resistance of rotary instruments has been deeply investigated by determining all parameters that can influenced it, that can be summarized in: (1) Tooth-related factors, (2) Strategy-related factors and (3) Instrument-related factors. This study was conducted to examine the influence of shaft length on torsional resistance of a nickel–titanium rotary instrument and if it should be considered as an Instrument-related factor. With this aim, 120 Twisted Files Adaptive M-L (TFA M-L) NiTi instruments (SybronEndo, Orange, CA, USA) were divided into 6 experimental groups (n = 20), according to instruments length and size: Group 1, 20 TFA M-L1 25/08 23 mm; Group 2, 20 TFA M-L1 25/08 27 mm; Group 3, 20 TFA M-L2 35/06 23 mm; Group 4, 20 TFA M-L2 35/06 27 mm; Group 5, 20 TFA M-L3 50/04 23 mm; and Group 6, 20 TFA M-L3 50/04 27 mm. All instruments were submitted to a static torsional test, blocking each instrument at 3 mm from the tip and rotating it until its fracture. Torque to Fracture (TtF) and fragments length were registered and all data were statistically analyzed. Results showed that Groups 2, 4 and 6 had a higher TtF, respectively, than Groups 1, 3 and 5, which differ from the former just for shaft length. Group 6 showed the highest torsional resistance (1.31 ± 0.08 Ncm), whilst Group 1 the lowest (0.40 ± 0.08 Ncm). According to that, it can be stated that the longer the instrument, the higher the torsional resistance is, proving that shaft length should be considered as an important factor about torsional resistance.

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