Evaluation of kinetic friction between regular and colored titanium molybdenum alloy archwires.

AIM: The aim of this study was to evaluate the kinetic frictional properties of colored titanium molybdenum alloy (TMA) archwires (purple-coated TMA and honey dew-coated TMA) and the regular TMA archwires. MATERIALS AND METHODS: The experiment comprised of three groups, Group I - Regular TMA archwires, Group II - Purple-coated TMA archwires, Group III - Honey dew-coated TMA wires involving 21 samples each that were evaluated for their frictional properties using Instron Universal Testing Machine. RESULTS: The results were subjected to statistical analysis using analysis of variance wherein Group I Regular TMA wires revealed mean kinetic frictional value of 8.236 N and a standard deviation of 0.4038 N, while Group II (purple-coated TMA wires) showed a mean value of 5.297 N, standard deviation of 0.3128 N and Group III (honey dew-coated TMA wires) showed a mean value of 4.206 N and a standard deviation of 0.5353 N. CONCLUSION: The kinetic frictional values are higher for regular TMA wire exhibiting superior characteristic of color-coated TMA. Wires exhibiting superior characteristics are color-coated TMA wires, especially honey dew-coated TMA wires over the regular and purple-coated TMA wires. These superior properties of newly introduced wires can be considered for its application in both details friction and frictionless mechanics in retraction phase of fixed orthodontic treatment.

Evaluating the Correlation between Anteroposterior and Mediolateral Compensatory Curves and their Influence on Dentoskeletal Morphology-An In vitro CBCT Study.

INTRODUCTION: To date, many orthodontist corrects malocclusion based on patients aesthetic concern and fails to correct the compensatory curves. This scenario is due to less insight on understanding relationship of compensatory curves and its correlation in treatment prognosis. AIM: The purpose of this study was to evaluate the correlation between the curve of Spee, curve of Monson and curve of Wilson, their influence on dentoskeletal morphology and their contribution to occlusal stability. MATERIALS AND METHODS: This study included 104 non-orthodontic models. The study casts were subdivided into two groups, Group-I consist 52 non- orthodontic models with Class-I molar relationship and Group-II consist of 52 non- orthodontic models with Class-II molar relationship. Curve of Spee was measured with digital vernier caliper, curve of Monson estimated using specially made sphere (7″inch, 8″ inch and 9″inch) and curve of Wilson was evaluated using Cone Beam Computed Technology (CBCT). RESULTS: Mean value for curve of Spee obtained for Group I and Group II is 1.844 mm and 3.188 mm. For curve of Monson, the mean value obtained for Group I and Group-II is 7.65 inches and 7.40 inches. The mean degree obtained for the curve of Wilson for Group I and Group-II is 12.05 and 16.49. The result showed positive correlation between curve of Spee and curve of Wilson and no correlation between curve of Monson and curve of Wilson and no correlation between curve of Spee and curve of Monson. The Pearson correlation coefficient analysis from the study confirmed these results. CONCLUSION: The results showed positive correlation between curve of spee and curve of Wilson. The data found in this study can be applied clinically for Class I and Class II malocclusion patients on diagnosis and treatment planning.

Contrast microbubbles improve diagnostic yield in ICU patients with poor echocardiographic windows.

OBJECTIVE: To determine the value of contrast echocardiographic studies in patients admitted to ICUs who have poor echocardiographic windows secondary to COPD, ventilator use, or inability to obtain optimal positioning for the echocardiogram. DESIGN: A prospective comparison study of technically difficult patients in the ICU. OUTCOME MEASURE: The total scores for the left ventricle (LV) in the two-chamber and four-chamber views were calculated at baseline and following injection of 1 to 2 mL of a contrast agent. The mean numbers of segments visualized in all patients at baseline and after injection of contrast agent were compared to assess the effect on improved visualization. RESULTS: Forty consecutive patients underwent echocardiography in the ICU for evaluation of LV function. Of these, 25 patients (63%) had poor visualization of the endocardium and required IV contrast agent. In these 25 patients, the average baseline segmental score was 4.5, compared to 11.6 in patients who received an IV contrast agent. Nineteen patients had an average baseline segmental score of 3.9 and were deemed to have a nondiagnostic study. After administration of IV contrast, all patients converted to a diagnostic study, with an average score of 11.6 segments visualized. CONCLUSIONS: Use of echocardiographic contrast agents in selected patients with poor baseline echocardiographic windows in the ICU setting significantly enhances segmental LV visualization and yielded 100% conversion from nondiagnostic to diagnostic studies.

Auger stimulated ion desorption of negative ions via K-capture radioactive decay.

We report on Auger stimulated ion desorption via Coulomb explosion from surface self-assembled alkylthiol and fluorocarbon molecular layers, triggered by K-capture decay of an imbedded radioactive 55Fe atom. The charge state of the ejecta is determined by charge exchange in binary atomic collisions in bulk and electron tunneling outside the solid, as well as by fragmentation of electronically excited molecules or molecular fragments. We describe the first nonbeam experiments documenting positive and abundant negative ion desorption due solely to core electron excitation after radioactive decay.

Field amplified stacking injection--capillary electrophoresis for quantitative analysis of released methacrylic acid from dental composites.

Field-amplified stacking injection-capillary electrophoresis (FASI-CE) applied for the first time to the study of dental materials is demonstrated in this report. CE was used to separate methacrylic acid from the other degraded components. Due to the background electrolyte being weakly basic and methacrylic acid being negatively charged, in-capillary enrichment of the analyte was achieved by FASI. A detection limit of less than 50 ppb was obtained with good reproducibility (relative standard deviation < 3%). The method was applied to the analysis of four commercially available dental composites. Results showed that FASI-CE was effective in monitoring the fabrication process and product quality of restorative materials fabricated from methacrylate-based composites by analyzing the amount of methacrylic acid released from the residual methacrylate monomers.

Release of methacrylic acid from dental composites.

OBJECTIVE: The aim of this study was to investigate the release of methacrylic acid from four commercial dental composite restoratives (Silux Plus (3M), Z100 (3M), Ariston pHc (Vivadent) and Surefil (Dentsply)). METHODS: Three specimen disks (10(0.2) mm in diameter and 2(0.2) mm thick), were prepared for each material using custom-made molds. Each disk was placed in artificial saliva for 24 h at 37 degrees C, rinsed and subsequently immersed in 1.5 ml of deionised water in an airtight glass container. The container was continuously shaken at a speed of 80 rpm for 24 h at 37 degrees C in an orbital incubator. After 24 h (Day 1), the water was removed and analyzed. The specimen disk was then re-immersed into another 1.5 ml of fresh deionised water. The procedure of removing and refilling of the water was repeated for a total of 7 days. The sample solutions were filtered and injected into the capillary electrophoresis system for analysis immediately after collection. Statistical analysis was performed by ANOVA and Scheffe's test. RESULTS: For Days 1-7, methacrylic acid released in water at 37 degrees C by Ariston was significantly greater than that of the other composites. Ranking from least to greatest total (cumulative over 7 days) methacrylic acid release was as follows: Z100 (5.66 ppm) < Silux (8.81 ppm) < Surefil (20.21 ppm) < Ariston (519.04 ppm). Methacrylic acid release was greatest at Day 1 for all materials and generally decreased with time. SIGNIFICANCE: Some composites may release high levels of methacrylic acid. The biological effects of such high levels of methacrylic acid is not known and warrant further in vivo and in vitro investigations.

Characterization of photooxidized self-assembled monolayers and bilayers by spontaneous desorption mass spectrometry.

We show that selected self-assembled monolayers (SAMs) and bilayers are readily characterized by the application of controlled photooxidation and spontaneous desorption mass spectrometry (SDMS) in the negative ion mode. Additionally, SDMS is used to characterize organic and inorganic anionic species adsorbed to the surface of a positively charged SAM surface, 2-aminoethanethiol (AET). Prominent peaks are observed that correspond both to the sulfonate form of each SAM and bilayer and to the anion form of each molecule adsorbed to AET. In addition, fragments of the oxidized thin films were also observed at m/z 80 (SO3-) and 97 (HSO4-). Other prominent fragment peaks more characteristic of the molecule are also seen in the mass spectra.