scholarly journals “In Vitro” Study About Variables that Influence in Arch Friction with Conventional and Self-Ligating Brackets

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3279
Author(s):  
Javier Moyano ◽  
Laia Mases ◽  
Telmo Izeta ◽  
Teresa Flores ◽  
Javier Fernández-Bozal ◽  
...  
Keyword(s):  
Treatment Time ◽  
In Vitro Study ◽  
Static Friction ◽  
Patient Comfort ◽  
Test Machine ◽  
Total Treatment Time ◽  
In Vitro Simulation ◽  
Hybrid Section ◽  
Friction Reducer

Many advantages have been described surrounding self-ligating (SL) brackets compared to metallic conventional ligating (CL) brackets, such as: Less total treatment time, alignment efficiency, patient comfort, plaque retention, and low friction. The objective of this in vitro simulation was to know the variables that affect arch displacement in CL and SL brackets—active (ASL) and passive (PSL)—and analyze if static friction values are affected by bracket design, arch wire section, kind of ligature, and use of a friction reducer agent (FRA) in a wet state. Larger values of static friction were found in CL with metallic ligature (ML) (8.01 ± 1.08 N/mm) and elastic ligature (EL) (6.96 ± 0.48 N/mm). Lower values were found in PSL brackets combined with FRA (0.58 ± 0.21 N/mm). The study was carried out using different stereographical models of a maxillary upper right quadrant with canine, first and second premolar, and first molar bonded brackets. A section of 25 mm of 0.019 × 0.025” stainless steel arch with a rectangular section (SS) and hybrid section (HY) was inserted into the different bracket models. Static friction values were collected using a universal test machine in wet conditions and testing the effect of a friction reducer agent (FRA). To assure the reliability of the study, different wire combinations were repeated after two weeks by the same operator and a linear analysis of regression was done. Each bracket model analysis—with the different wires, use of the FRA, and comparison among brackets in similar conditions—was done using an ANOVA test with a confidence interval of 95% and comparative Post-Hoc tests (LSD). In this in vitro simulation we found higher static friction values in CL compared to ASL and PSL. In PSL, lower values were achieved. CL brackets using ML showed the highest static friction values with a great variability. In this setting, the use of HY wires did not reduce static friction values in ASL and PSL, while in CL brackets with EL friction the values were reduced significantly. An FRA combined with ASL reduced significantly static friction values but not with PSL. In the case of CL, the FRA effect was higher with SS and better than with HY wires. ML values were similar to ASL static friction. The direct extrapolation of the results might be inaccurate, since all these findings should be tested clinically to be validated.

scholarly journals Evaluation of metallic brackets adhesion after the use of bleaching gels with and without amorphous calcium phosphate (ACP): in vitro study

2013 ◽  
Vol 18 (3) ◽  
pp. 101-106 ◽  
Author(s):  
Sissy Maria Mendes Machado ◽  
Diego Bruno Pinho do Nascimento ◽  
Robson Costa Silva ◽  
Sandro Cordeiro Loretto ◽  
David Normando
Keyword(s):  
Calcium Phosphate ◽  
Bond Strength ◽  
Amorphous Calcium Phosphate ◽  
Shear Bond Strength ◽  
Mechanical Test ◽  
In Vitro Study ◽  
Control Group ◽  
Test Machine ◽  
Tooth Whitening

OBJECTIVE: To evaluate in vitro the effects of tooth whitening using gel with Amorphous Calcium Phosphate (ACP) on the bond strength of metal brackets. METHODS: Thirty-six bovine incisors were sectioned at the crown-root interface, and the crowns were then placed in PVC cylinders. The specimens were divided into 3 groups (n = 12) according to whitening treatment and type of gel used, as follows: G1 (control) = no whitening; G2 = whitening with gel not containing ACP (Whiteness Perfect - FGM), G3 = whitening with gel containing ACP (Nite White ACP - Discus Dental). Groups G2 and G3 were subjected to 14 cycles of whitening followed by an interval of 15 days before the bonding of metal brackets. Shear bond strength testing was performed on a Kratos universal test machine at a speed of 0.5 mm/min. After the mechanical test, the specimens were assessed to determine the adhesive remnant index (ARI). The results were subjected to ANOVA, Tukey's test and Kruskal-Wallis test (5%). RESULTS: Significant differences were noted between the groups. Control group (G1 = 11.10 MPa) showed a statistically higher shear bond strength than the groups that underwent whitening (G2 = 5.40 Mpa, G3 = 3.73 MPa), which did not differ from each other. There were no significant differences between the groups in terms of ARI. CONCLUSION: Tooth whitening reduces the bond strength of metal brackets, whereas the presence of ACP in the whitening gel has no bearing on the results.

scholarly journals Comparison of Shear Bond Strength of MIM Technology Brackets with Conventional and Rail-Shaped Mesh Bases: An In Vitro Study

2019 ◽  
Vol 13 (1) ◽  
pp. 255-260
Author(s):  
Francisco Molina ◽  
Karina Maria Salvatore Freitas ◽  
Maria Cristina Rockenbach Binz Ordóñez ◽  
Emerson Flamarion Cruz ◽  
Rafael Pinelli Henriques ◽  
...  
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Dental Enamel ◽  
In Vitro Study ◽  
Metal Injection Molding ◽  
Test Machine ◽  
Intergroup Comparison ◽  
Significant Difference ◽  
Mim Technology

Objective: The objective of this study was to evaluate in vitro the shear bond strength of two types of MIM (Metal Injection Molding) technology brackets, one with conventional mesh base and the other with rail-shaped mesh base. Materials and Methods: Forty human premolars received the bonding of 2 types of brackets: Group 1- 20 Synergy metal brackets (Rocky Mountain) with conventional mesh base and Group 2-20 H4 brackets (OrthoClassic) with rail-shaped mesh base. Both brackets were bonded with Resilience photopolymerizable resin (OrthoTechnology). The specimens were coupled to a Tinius Olsen universal test machine where the shear test was performed using a chisel. In addition, the amount of remaining resin in tooth crown with the ImageJ program was evaluated and the Adhesive Remnant Index (ARI). Intergroup comparison was performed by the independent t test and Chi-square test. Results: There was no statistically significant difference between the groups for any of the measures evaluated indicating that the mesh type of the brackets’ base with MIM technology did not influence the shear bond strength of the brackets (shear bond strength, p=0.191; maximum load registered, p=0.244). There was also no difference between the percentage (p=0.602) and area of remaining resin in the teeth (p=0.805) and IRA (p=0.625) between the Synergy and H4 groups. Conclusion: Shear bond strength was similar in the two types of brackets with MIM technology evaluated. In addition, the remaining resin in the dental enamel of two types of brackets were also similar.

scholarly journals Rehardening and the Protective Effect of Gamma-Polyglutamic Acid/Nano-Hydroxyapatite Paste on Surface-Etched Enamel

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4268
Author(s):  
Nai-Chia Teng ◽  
Aditi Pandey ◽  
Wei-Hsin Hsu ◽  
Ching-Shuan Huang ◽  
Wei-Fang Lee ◽  
...  
Keyword(s):  
Protective Effect ◽  
Treatment Time ◽  
In Vitro Study ◽  
Polyglutamic Acid ◽  
Short Treatment ◽  
Surface Parameters ◽  
Roughness Change ◽  
Atomic Force ◽  
Etched Surface

Many revolutionary approaches are on the way pertaining to the high occurrence of tooth decay, which is an enduring challenge in the field of preventive dentistry. However, an ideal dental care material has yet to be fully developed. With this aim, this research reports a dramatic enhancement in the rehardening potential of surface-etched enamels through a plausible synergistic effect of the novel combination of γ-polyglutamic acid (γ-PGA) and nano-hydroxyapatite (nano-HAp) paste, within the limitations of the study. The percentage of recovery of the surface microhardness (SMHR%) and the surface parameters for 9 wt% γ-PGA/nano-HAp paste on acid-etched enamel were investigated with a Vickers microhardness tester and an atomic force microscope, respectively. This in vitro study demonstrates that γ-PGA/nano-HAp treatment could increase the SMHR% of etched enamel to 39.59 ± 6.69% in 30 min. To test the hypothesis of the rehardening mechanism and the preventive effect of the γ-PGA/nano-HAp paste, the surface parameters of mean peak spacing (Rsm) and mean arithmetic surface roughness (Ra) were both measured and compared to the specimens subjected to demineralization and/or remineralization. After the treatment of γ-PGA/nano-HAp on the etched surface, the reduction in Rsm from 999 ± 120 nm to 700 ± 80 nm suggests the possible mechanism of void-filling within a short treatment time of 10 min. Furthermore, ΔRa-I, the roughness change due to etching before remineralization, was 23.15 ± 3.23 nm, while ΔRa-II, the roughness change after remineralization, was 11.99 ± 3.90 nm. This statistically significant reduction in roughness change (p < 0.05) implies a protective effect against the demineralization process. The as-developed novel γ-PGA/nano-HAp paste possesses a high efficacy towards tooth microhardness rehardening, and a protective effect against acid etching.

scholarly journals Tensile Strength of Novel Nonabsorbable PTFE (Teflon®) versus Other Suture Materials: An In Vitro Study

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
José Arce ◽  
Alondra Palacios ◽  
Daniel Alvítez-Temoche ◽  
G. Mendoza-Azpur ◽  
Percy Romero-Tapia ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Immersion Time ◽  
Artificial Saliva ◽  
In Vitro Study ◽  
Test Machine ◽  
Suture Materials ◽  
Polyglactin 910 ◽  
Significant Difference ◽  
Failure Point

Objective. To compare the in vitro tensile strength of sutures used in implant surgery according to the type of thread and the immersion time in artificial saliva. Methods. For the development of the study, three suture materials were used: polyglactin 910 (PG), black silk (BS), and Teflon (PTFE) 4-0; 150 samples were used, which were divided among each type of suture and then subdivided into five groups of 10 according to the various immersion times (baseline, 3, 7, 14, and 21 days) in artificial saliva. A universal test machine was used to measure the tensile strength at a speed of 25 cm/min, stretch each sample until the material fails, and record the maximum strength in Newtons (N). Finally, the failure point of the samples was evaluated at 10× increase using a stereromicroscope (Leica Biosystems). Results. When analyzing the tensile strength of the various groups of sutures, it was evidenced that PG maintained its strength, which was lowest at baseline and highest at 21 days. When performing the statistical inference of PG and PTFE, it was found that the force necessary to achieve detachment was not statistically significant (p<0.05). However, it was shown that the force necessary to achieve rupture in the BS group was statistically significant (p=0.001). Conclusion. To sum up, when comparing the in vitro tensile strength of PG, BS, and PTFE sutures at baseline and 3, 7, 14, and 21 days, there was no statistically significant difference. This indicates that all sutures used present sufficient performance that remains resistant as time progresses.

scholarly journals A Comparative Evaluation of Static Frictional Resistance Using Various Methods of Ligation at Different Time Intervals: An In Vitro Study

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Amanpreet Singh Natt ◽  
Amandeep Kaur Sekhon ◽  
Sudhir Munjal ◽  
Rohit Duggal ◽  
Anup Holla ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Artificial Saliva ◽  
In Vitro Study ◽  
Frictional Resistance ◽  
Static Friction ◽  
Significant Difference ◽  
Dry Conditions ◽  
The Mean ◽  
Time Periods

Aim. To compare and evaluate the static frictional resistance offered by the four different types of ligation methods in both dry and wet conditions and at different durations when immersed in artificial saliva.Material and Methods. Alastik Easy to Tie modules, Super Slick Mini Stix elastomeric modules, Power “O” modules, and 0.009″Stainless Steel ligatures were used to compare the static friction using maxillary canine and premolar Preadjusted Edgewise brackets with 0.022″× 0.028″slot and 0.019″× 0.025″stainless steel wires.Results. The mean frictional resistance for Alastik modules was the lowest and that of Stainless Steel ligatures was found to be highest among the four groups compared and the difference among the four groups was statistically significant (P<0.005). The mean static frictional resistance in all groups under dry conditions was lower than that under wet conditions. No statistical significant differences were found when the groups were compared at different time periods of immersion in artificial saliva.Conclusion. This study concludes that the Alastik modules showed the lowest mean static frictional forces compared to any other ligation method, though no significant difference was found for different time periods of immersion in the artificial saliva.

scholarly journals Evaluation of degradation of force of esthetic elastomeric chains

2019 ◽  
Vol 48 ◽  
Author(s):  
Mayra Teixeira Cortat LUCINDO ◽  
Diego Patrik Alves CARNEIRO ◽  
Felipe Alexandre de SOUZA ◽  
Américo Bortolazzo CORRER ◽  
Heloisa Cristina VALDRIGHI
Keyword(s):  
Repeated Measures ◽  
Artificial Saliva ◽  
In Vitro Study ◽  
Time Interval ◽  
Test Machine ◽  
Reduction In Force ◽  
Original Length ◽  
The Aesthetic ◽  
Elastomeric Chains

Abstract Introduction Elastomers are considered important allies to orthodontic treatment and due to the aesthetic demand, aesthetic elastomers are increasingly used in adult patients. Objective The aim of this experimental in vitro study was to evaluate the degradation of force of esthetic elastomeric chains, of three different sizes: short, medium and long. Material and method For evaluating the degradation of force, 90 elastomeric chain segments were used, divided into 9 Groups (n=10), as follows: Morelli short elastomer, Morelli medium, Morelli long, Orthometric short, Orthometric medium, Orthometric long, American Orthodontic short, American Orthodontic medium and American Orthodontic long. Acrylic plates with pins were used to provide stretching of the elastomeric chains. The initial stretching force of the elastomeric chain was 150 grams, measured by a tensiometer. After this, they were prestretched to 50% of their original length, measured in an Instron 4411 Universal test machine, and placed on the seating pin on the plate. The plate was immersed in artificial saliva at 37 °C in a plastic receptacle, and removed for measurement after a time interval of 21 days. For statistical analysis, the methodology of mixed models for repeated measures in time and Tukey-Kramer test were used. Degradation of the forces was analyzed by 2-way analysis of variance (ANOVA) and the Tukey test. Result All the elastomeric chains showed statistically significant reduction in force (p<0.05). The American Orthodontic elastomeric chains showed higher reduction in force values, irrespective of the elastic size (p<0.05). Conclusion The three commercial brands studied underwent significant reduction in the quantity of force released; the American Orthodontic brand of elastomer showed the highest value of degradation in force.

scholarly journals Evaluation of biofilm accumulation on and deactivation force of orthodontic Ni-Ti archwires before and after exposure to an oral medium: A prospective clinical study

2020 ◽  
Vol 14 (1) ◽  
pp. 41-47
Author(s):  
Diogo M. Sapata ◽  
Adilson L. Ramos ◽  
Sérgio Sábio ◽  
David Normando ◽  
Renata C. Pascotto
Keyword(s):  
Repeated Measures ◽  
In Vitro Study ◽  
The Other ◽  
Prospective Clinical Study ◽  
Test Machine ◽  
Before And After ◽  
Post Test ◽  
Spearman Test ◽  
Scanning Electron

Background . This in vitro study aimed to evaluate biofilm accumulation on and deactivation force of orthodontic nickeltitanium (NiTi) archwires before and after exposure to an oral medium. Methods. Four commercial brands of orthodontic NiTi 0.016" archwires were examined before and after exposure to the oral medium for 4 weeks. Six archwire segments, 30 mm in length, from each manufacturer were tested in a device with four selfligating brackets, channel 0.022", adapted to a universal test machine to evaluate the deactivation force between 0.5 and 3 mm of deflection. The presence of biofilm on the archwire surfaces was evaluated by scanning electron microscopy, before and after exposure to the oral medium. The Wilcoxon and kappa tests were applied to the biofilm scores, three-way ANOVA for repeated measures (Bonferroni post-test), and linear regression between biofilm and deactivation force. Results. The exposure to the oral medium promoted moderate to severe presence of debris on the archwire surfaces and caused a reduction in deactivation force for the Ormco and GAC brands, while maintaining them with adequate force levels. The MORELLI and ORTHOMETRIC archwires underwent no significant reduction in deactivation force; moreover, these maintained elevated levels of force after exposure to the oral medium. The Spearman test indicated a low correlation between biofilm accumulation and deflection force for the Morelli (R2=0.132 and P=0.683) and Orthometric (R2=0.308 and P=0.330) brands. On the other hand, the GAC (R=0.767 and P=0.004) and ORMCO (R=0.725 and P=0.008) brands exhibited statistically significant correlation between these variables. Conclusion. Exposure to the oral medium for one month might give rise to significant changes in the dissipation of forces of orthodontic NiTi archwires, resulting from biofilm accumulation.

scholarly journals Optimizing high-flow nasal cannula flow settings in adult hypoxemic patients based on peak inspiratory flow during tidal breathing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Li ◽  
J. Brady Scott ◽  
James B. Fink ◽  
Brooke Reed ◽  
Oriol Roca ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Inspiratory Flow ◽  
High Flow ◽  
Nasal Cannula ◽  
Vitro Study ◽  
Patient Comfort ◽  
High Flow Nasal Cannula ◽  
Optimal Flow ◽  
The Individual

Abstract Background Optimal flow settings during high-flow nasal cannula (HFNC) therapy are unknown. We investigated the optimal flow settings during HFNC therapy based on breathing pattern and tidal inspiratory flows in patients with acute hypoxemic respiratory failure (AHRF). Methods We conducted a prospective clinical study in adult hypoxemic patients treated by HFNC with a fraction of inspired oxygen (FIO2) ≥ 0.4. Patient’s peak tidal inspiratory flow (PTIF) was measured and HFNC flows were set to match individual PTIF and then increased by 10 L/min every 5–10 min up to 60 L/min. FIO2 was titrated to maintain pulse oximetry (SpO2) of 90–97%. SpO2/FIO2, respiratory rate (RR), ROX index [(SpO2/FIO2)/RR], and patient comfort were recorded after 5–10 min on each setting. We also conducted an in vitro study to explore the relationship between the HFNC flows and the tracheal FIO2, peak inspiratory and expiratory pressures. Results Forty-nine patients aged 58.0 (SD 14.1) years were enrolled. At enrollment, HFNC flow was set at 45 (38, 50) L/min, with an FIO2 at 0.62 (0.16) to obtain an SpO2/FIO2 of 160 (40). Mean PTIF was 34 (9) L/min. An increase in HFNC flows up to two times of the individual patient’s PTIF, incrementally improved oxygenation but the ROX index plateaued with HFNC flows of 1.34–1.67 times the individual PTIF. In the in vitro study, when the HFNC flow was set higher than PTIF, tracheal peak inspiratory and expiratory pressures increased as HFNC flow increased but the FIO2 did not change. Conclusion Mean PTIF values in most patients with AHRF were between 30 and 40 L/min. We observed improvement in oxygenation with HFNC flows set above patient PTIF. Thus, a pragmatic approach to set optimal flows in patients with AHRF would be to initiate HFNC flow at 40 L/min and titrate the flow based on improvement in ROX index and patient tolerance. Trial registration: ClinicalTrials.gov (NCT03738345). Registered on November 13th, 2018. https://clinicaltrials.gov/ct2/show/NCT03738345?term=NCT03738345&draw=2&rank=1

Assessing the dose rate delivery of helical TomoTherapy prostate and head & neck treatments

2021 ◽  
Author(s):  
Panagiotis Kouris ◽  
Argyris Moutsatsos ◽  
Eleftherios P Pappas ◽  
Ivelina Beli ◽  
Panagiotis Pantelakos ◽  
...  
Keyword(s):  
Dose Rate ◽  
Helical Tomotherapy ◽  
Treatment Time ◽  
Anatomical Site ◽  
Dose Rates ◽  
Total Treatment Time ◽  
Total Treatment ◽  
Treatment Data ◽  
Target Volumes

Abstract The dose rate distributions delivered to 55 prostate and head & neck (H&N) cancer patients treated with a helical TomoTherapy (HT) system were resolved and assessed with regard to pitch and field width defined during treatment planning. Statistical analysis of the studied cases showed that the median treatment delivery time was 4.4 min and 6.3 min for the prostate and H&N cases, respectively. Dose rate volume histogram data for the studied cases showed that the 25% and 12% of the volume of the planning target volumes of the prostate and H&N cases are irradiated with a dose rate of greater or equal to 1 Gy/min. Quartile dose rate (QDR) data confirmed that in HT, where the target is irradiated in slices, most of the dose is delivered to each voxel of the target when it travels within the beam. Analysis of the planning data from all cases showed that this lasts for 68 s (median value). QDRs results showed that using the 2.5 cm field width, 75% of the prescribed dose is delivered to target voxels with a median dose rate of at least 3.2 Gy/min and 4.5 Gy/min, for the prostate and H&N cases, respectively. Systematically higher dose rates were observed for the H&N cases due to the shallower depths of the lesions in this anatomical site. Delivered dose rates were also found to increase with field width and pitch setting, due to the higher output of the system which, in general, results in accordingly decreased total treatment time. The biological effect of the dose rate findings of this work needs to be further investigated using in-vitro studies and clinical treatment data.

scholarly journals Evaluation of Different Post Lengths’ Effect on Fracture Resistance of a Glass Fiber Post System

2008 ◽  
Vol 02 (01) ◽  
pp. 23-28 ◽  
Author(s):  
Necdet Adanir ◽  
Sema Belli
Keyword(s):  
Glass Fiber ◽  
Fracture Resistance ◽  
Testing Machine ◽  
In Vitro Study ◽  
Test Machine ◽  
Root Fracture ◽  
Crown Length ◽  
Luting Cement ◽  
Significant Difference

ABSTRACTObjectives: The purpose of this in vitro study was to evaluate the influence of different post lengths upon root fracture resistance.Methods: 78 maxillary central teeth with similar dimensions were mounted in acrylic blocks with artificial silicone periodontal ligaments. Combinations of post lengths of 6 mm (shorter than 1/1 clinical crown length), 9 mm (1/1 clinical crown length), and 12 mm (longer than 1/1 clinical crown length) made up 6 different groups consisting of 13 teeth each. The glass fiber posts (Snowpost) were cemented with Super-Bond C&B and Panavia F luting cement. Composite-resin cores were made with Clearfil PhotoCore. The specimens were tested in a universal test machine. The testing machine applied controlled loads to the core, 2 mm from its incisal edge, on the palatal side at an angle 135 degrees to the long axis of the root. The testing machine was set at a crosshead speed of 5mm per minute. All samples were loaded until failure.Results: There was no statistically significant difference between cements (P>.05). Posts shorter than clinical crown length, demonstrated root fracture under significantly lower loading forces (P<.05).Conclusion: Usage of posts shorter than clinical crowns should be avoided to eliminate clinical failure. (Eur J Dent 2008;2:23-28)

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