scholarly journals In Vitro Corrosion Behavior of Lingual Orthodontic Archwires

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Carlos Suárez ◽  
Teresa Vilar ◽  
Pablo Sevilla ◽  
Javier Gil
Keyword(s):  
Differential Scanning Calorimetry ◽  
Stainless Steel ◽  
Rhombohedral Phase ◽  
Nickel Titanium ◽  
Scanning Calorimetry ◽  
Lingual Orthodontics ◽  
Phase Transition Temperatures ◽  
Different Types ◽  
Orthodontic Archwires

Objectives. To investigate the in vitro electrochemical corrosive behavior of archwires used in lingual orthodontics and the effects on the phase transition temperatures.Materials and Methods. Six different types of archwires of stainless steel, titanium-molybdenum, nickel-titanium and nickel-titanium-copper were used. Corrosion tests were performed following ISO-standard 10993-15:2000. Differential scanning calorimetry and scanning electron microscopy were used.Results. The stainless steel archwires showed anEpitaround −600 mV, and those of titanium alloys showedEpitvalues around 1000 mV. Differential scanning calorimetry detected a rhombohedral phase in nickel-titanium archwires, while it was not detected in nickel-titanium-copper wires. A difference of 2°C to 3.5°C from the manufacturer's claim was found in the as-received and polarized samples, respectively.Conclusions. The 0.016 stainless steel archwires were found to be the less resistant to corrosion. A rhombohedral phase was detected on the nickel-titanium archwires. No major differences were observed among groups concerning phase transformation temperatures.

scholarly journals In vitro biocompatibility of nickel-titanium esthetic orthodontic archwires

2016 ◽  
Vol 86 (5) ◽  
pp. 789-795 ◽  
Author(s):  
Roberto Rongo ◽  
Rosa Valletta ◽  
Rosaria Bucci ◽  
Virginia Rivieccio ◽  
Angela Galeotti ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Steel Wire ◽  
Nickel Titanium ◽  
Experimental Conditions ◽  
In Vitro Biocompatibility ◽  
Diphenyltetrazolium Bromide ◽  
Titanium Wire ◽  
Orthodontic Archwires ◽  
Niti Wires

ABSTRACT Objective:  To investigate the cytotoxicity of nickel-titanium (NiTi) esthetic orthodontic archwires with different surface coatings. Materials and Methods:  Three fully coated, tooth-colored NiTi wires (BioCosmetic, Titanol Cosmetic, EverWhite), two ion-implanted wires (TMA Purple, Sentalloy High Aesthetic), five uncoated NiTi wires (BioStarter, BioTorque, Titanol Superelastic, Memory Wire Superelastic, and Sentalloy), one β-titanium wire (TMA), and one stainless steel wire (Stainless Steel) were considered for this study. The wire samples were placed at 37°C in airtight test tubes containing Dulbecco’s Modified Eagle’s Medium (0.1 mg/mL) for 1, 7, 14, and 30 days. The cell viability of human gingival fibroblasts (HGFs) cultured with this medium was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by a two-way analysis of variance (α  =  .05). Results:  The highest cytotoxic effect was reached on day 30 for all samples. The archwires exhibited a cytotoxicity on HGFs ranging from “none” to “slight,” with the exception of the BioTorque, which resulted in moderate cytotoxicity on day 30. Significant differences were found between esthetic archwires and their uncoated pairs only for BioCosmetic (P  =  .001) and EverWhite (P < .001). Conclusions:  Under the experimental conditions, all of the NiTi esthetic archwires resulted in slight cytotoxicity, as did the respective uncoated wires. For this reason their clinical use may be considered to have similar risks to the uncoated archwires.

scholarly journals Comparative Evaluation of Frictional forces between different Archwire-bracket Combinations

2014 ◽  
Vol 4 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Vinit Singh ◽  
Swati Acharya ◽  
Satyabrata Patnaik ◽  
Smruti Bhusan Nanda
Keyword(s):  
Stainless Steel ◽  
Tooth Movement ◽  
Testing Machine ◽  
Frictional Resistance ◽  
Nickel Titanium ◽  
Orthodontic Bracket ◽  
Fixed Appliance ◽  
Beta Titanium ◽  
Frictional Forces

Introduction: During sliding mechanics, frictional resistance is an important counterforce to orthodontic tooth movement; whichmust be controlled to allow application of light continuous forces.Objective: To investigate static and kinetic frictional resistance between three orthodontic brackets: ceramic, self-ligating, andstainless steel, and three 0.019×0.025” archwires: stainless steel, nickel-titanium, titanium-molybdenum.Materials & Method: The in vitro study compared the effects of stainless steel, nickel-titanium, and beta-titanium archwires onfrictional forces of three orthodontic bracket systems: ceramic, self-ligating, and stainless steel brackets. All brackets had 0.022”slots, and the wires were 0.019×0.025”. Friction was evaluated in a simulated half-arch fixed appliance on a testing machine. Thestatic and kinetic friction data were analyzed with 1-way analysis of variance (ANOVA) and post-hoc Duncan multiple rangetest.Result: Self-ligating (Damon) brackets generated significantly lower static and kinetic frictional forces than stainless steel (Gemini)and ceramic brackets (Clarity). Among the archwire materials, Beta-titanium showed the maximum amount of frictional forceand stainless steel archwires had the lowest frictional force.Conclusion: The static and kinetic frictional force for stainless steel bracket was lowest in every combination of wire.

The preparation, characterization, structure and dissolution analysis of apremilast solvatomorphs

2017 ◽  
Vol 73 (4) ◽  
pp. 305-313 ◽  
Author(s):  
Yun-Deng Wu ◽  
Xiao-Lei Zhang ◽  
Xiao-Hong Liu ◽  
Jian Xu ◽  
Mei Zhang ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Hydrogen Bonding ◽  
Psoriatic Arthritis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Dissolution Rates ◽  
X Ray ◽  
Similarity Factor ◽  
Hydrogen Bonding Interactions

Apremilast (AP) {systematic name: (S)-2-[1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethyl]-4-acetamidoisoindoline-1,3-dione} is an inhibitor of phosphodieasterase-4 (PDE4) and is indicated for the treatment of adult patients with active psoriatic arthritis. The ability of AP to form solvates has been investigated and three solvatomorphs of AP, namely, the AP ethyl acetate hemisolvate, C22H24N2O7S·0.5C4H8O2, the AP toluene hemisolvate, C22H24N2O7S·0.5C7H8, and the AP dichloromethane monosolvate, C22H24N2O7S·CH2Cl2, were obtained. The three AP solvatomorphs were characterized by X-ray powder diffraction, thermogravimetric analysis and differential scanning calorimetry. Single-crystal X-ray diffraction was used to analyze the structures, crystal symmetry, packing modes, stoichiometry and hydrogen-bonding interactions of the solvatomorphs. In addition, dissolution analyses were performed to study the dissolution rates of different AP solvatomorph tablets in vitro and to make comparisons with commercial apremilast tablets (produced by Celgene); all three solvatomorphs showed similar dissolution rates and similar values of the similarity factor f2 in a comparison of their dissolution profiles.

Analytical Models for the Systematic Errors of Differential Scanning Calorimetry Instruments

Volume 1 ◽  
2004 ◽  
Author(s):  
Adrian S. Sabau ◽  
Wallace D. Porter
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Change ◽  
Computational Analysis ◽  
Systematic Errors ◽  
Analytical Models ◽  
Transition Temperatures ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Dsc Measurements ◽  
Phase Transition Temperatures

Differential Scanning Calorimetry (DSC) measurements are routinely used to determine enthalpies of phase change, phase transition temperatures, glass transition temperatures, and heat capacities. In order to obtain data on the amount of phases during phase change, time-temperature lags, which are inherent to the measurement process, must be estimated through a computational analysis. An analytical model is proposed for the systematic error of the instrument. Numerical simulation results are compared against experimental data obtained at different heating and cooling rates.

Differential scanning calorimetry of human blood serum exposed in vitro to X-ray radiation

2019 ◽  
Vol 680 ◽  
pp. 178358 ◽  
Author(s):  
Agnieszka Kiełboń ◽  
Anna Michnik ◽  
Kinga Polaczek Grelik ◽  
Klaudia Duch ◽  
Ewa Sadowska-Krępa
Keyword(s):  
Differential Scanning Calorimetry ◽  
Blood Serum ◽  
Human Blood ◽  
Human Blood Serum ◽  
Scanning Calorimetry ◽  
X Ray

scholarly journals Stepwise Glucoheptoamidation of Poly(Amidoamine) Dendrimer G3 to Tune Physicochemical Properties of the Potential Drug Carrier: In Vitro Tests for Cytisine Conjugates

Pharmaceutics ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 473 ◽  
Author(s):  
Anna Czerniecka-Kubicka ◽  
Piotr Tutka ◽  
Marek Pyda ◽  
Małgorzata Walczak ◽  
Łukasz Uram ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Physicochemical Properties ◽  
Drug Carrier ◽  
Human Fibroblasts ◽  
Pamam Dendrimer ◽  
In Vitro Tests ◽  
Scanning Calorimetry ◽  
Ζ Potential ◽  
Cell Accumulation

Third-generation poly(amidoamine) dendrimer (PAMAM) was modified by stepwise primary amine group amidation with d-glucoheptono-1,4-lactone. The physicochemical properties of the conjugates—size, ζ potential in lysosomal pH 5 and in neutral aqueous solutions, as well as intramolecular dynamics by differential scanning calorimetry—were determined. Internalization and toxicity of the conjugates against normal human fibroblasts BJ were monitored in vitro in order to select an appropriate carrier for a drug delivery system. It was found that initial glucoheptoamidation (up to 1/3 of amine groups of neat dendrimers available) resulted in increase of conjugate size and ζ potential. Native or low substituted dendrimer conjugates accumulated efficiently in fibroblast cells at nontoxic 1 µM concentration. Further substitution of dendrimer caused consistent decrease of size and ζ potential, cell accumulation, and toxicity. All dendrimers are amorphous at 36.6 °C as determined by differential scanning calorimetry (DSC). The optimized dendrimer, half-filled with glucoheptoamide substituents, was applied as carrier bearing two covalently attached cytisine molecules: a rigid and hydrophobic alkaloid. The conjugate with 2 cytisine and 16 glucoheptoamide substituents showed fast accumulation and no toxicity up to 200 µM concentration. The half-glucoheptoamidated PAMAM dendrimer was selected as a promising anticancer drug carrier for further applications.

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