scholarly journals Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252999
Author(s):  
António H. S. Delgado ◽  
Anne M. Young
Keyword(s):  
Repeated Measures ◽  
Light Exposure ◽  
Peak Height ◽  
Dihydrogen Phosphate ◽  
Difference Spectra ◽  
Significance Level ◽  
Noise Interference ◽  
Restorative Materials ◽  
Within Subjects ◽  
Urethane Dimethacrylate

Investigation of polymerisation kinetics using ATR-FTIR systems is common in many dental studies. However, peak selection methods to calculate monomer-polymer conversion can vary, consequently affecting final results. Thus, the aim of this study is to experimentally confirm which method is less prone to systematic errors. Three commercial restorative materials were tested–Vertise Flow (VF), Constic and Activa Bioactive Restorative Kids. Firstly, Attenuated Total Reflectance Fourier Transform Infra-Red (ATR-FTIR) (Spectrum One, Perkin-Elmer, UK) spectra of monomers were acquired—10-methacryloyloxy decyl dihydrogen phosphate (10-MDP), bisphenol-A glycidyl dimethacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), triethyelene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) to investigate proportionality of methacrylate peak heights versus concentration. Spectral changes upon light exposure of 2 mm discs of the restorative materials (irradiated for 20 s, LED curing unit 1100–1330 mW/cm2) were assessed to study polymerisation kinetics (n = 3), with continuous acquisition of spectra, before, during and after light exposure. Peak differences and degrees of conversion (DC %) were calculated using 1320/1336, 1320/1350 and 1636/1648 cm-1 as reaction/reference peaks. Inferential statistics included a MANOVA and within-subjects repeated measures ANOVA design (5% significance level). Proportionality of methacrylate peak height to concentration was confirmed, with the 1320/1352 cm-1 peak combination showing the lowest coefficient of variation (8%). Difference spectra of the polymerisation reaction showed noise interference around the 1500–1800 cm-1 region. Across the different materials, DC % results are highly dependent upon peak selection (p<0.001), with higher variability associated to the 1636 cm-1. Significant differences in the materials were only detected when the 1320 cm-1 peak was used (p<0.05). Within the same materials, methods were significantly different for Constic and Activa (p<0.05). It is possible to conclude that the 1320 cm-1 peak is more adequate to assess polymerisation of methacrylates and is therefore recommended.

scholarly journals Influence of Energy Beverages on the Surface Texture of Glass Ionomer Restorative Materials

2017 ◽  
Vol 18 (10) ◽  
pp. 937-942 ◽  
Author(s):  
Khalid H Al-Samadani
Keyword(s):  
Surface Roughness ◽  
Surface Texture ◽  
Repeated Measures ◽  
Immersion Time ◽  
Glass Ionomer ◽  
Paired Data ◽  
Significance Level ◽  
Restorative Materials ◽  
Erosive Effect ◽  
Red Bull

ABSTRACT Background and objective The objective of the study was to find whether energy beverages have an erosive effect, leading to a risk in the clinical performance of glass ionomer restorative materials. Aim This study evaluated the influence of energy beverages on the surface texture of glass ionomer restorative materials. Materials and methods Glass ionomer materials used were Ionofil Plus AC, GC EQUIA, and Ketac Molar; energy beverages are Code Red, Red Bull, and Power Horse. Specimens prepared were discs of 8 mm diameter and 3 mm thickness; specimens from each material were evaluated following aging with Code Red, Red Bull, and Power Horse energy beverages. Distilled water was used as a control. The surface roughness (Ra) was assessed by surface scanning interferometry. The surface roughness values (∆Ra and Ra) were measured for each specimen. The data were analyzed statistically using multiple repeated measures [analysis of variance (ANOVA)] and paired data t-test (p < 0.05 was considered as the significance level). Results The surface roughness (∆Ra and Ra) values before and after aging using Code Red, Red Bull, and Power Horse energy beverages differ significantly for all the materials regardless of the immersion time (p < 0.05). All the materials showed roughness changes after immersion periods of 1 day, 1 week, and 1 month. Conclusion It can be concluded that all energy beverage solutions used in this study had an adverse effect on the surface roughness degradation of the tested glass ionomers with increasing immersion time. Clinical significance Energy beverages have an erosive effect on glass ionomer, which influences the clinical importance of the material; it also has anticarious property because it releases the fluoride. How to cite this article Al-Samadani KH. Influence of Energy Beverages on the Surface Texture of Glass Ionomer Restorative Materials. J Contemp Dent Pract 2017;18(10):937-942.

scholarly journals Modelling ATR-FTIR Spectra of Dental Bonding Systems to Investigate Composition and Polymerisation Kinetics

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 760
Author(s):  
António HS Delgado ◽  
Anne M. Young
Keyword(s):  
Light Exposure ◽  
Ftir Spectra ◽  
Dihydrogen Phosphate ◽  
Dental Bonding ◽  
Significance Level ◽  
Spectral Changes ◽  
Methacrylate Monomers ◽  
Main Components ◽  
Adhesive Model ◽  
Bonding Systems

Component ratios and kinetics are key to understanding and optimising novel formulations. This warrants investigation of valid methods. Attenuated Total Reflectance Fourier Transform Infra-Red (ATR)-FTIR spectra of separate primers/adhesives were modelled using summed spectra of solvents (water, ethanol), methacrylate monomers (HEMA (hydroxyethyl methacrylate), Bis-GMA (bisphenol A glycidyl methacrylate), and 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)), and fillers, multiplied by varying fractions. Filler loads were obtained following their separation from the adhesives, by analysing three repetitions (n = 3). Spectral changes during light exposure at 37 °C (20 s, LED 1100–1330 mW/cm2) were used to determine polymerisation kinetics (n = 3). Independent samples T-test was used for statistical analysis (significance level of 5%). FTIR modelling suggested a primer solvent percentage of OBFL (Optibond FL) (30%) was half that of CFSE (Clearfil SE 2) (60%). OBFL included ethanol and water, while CFSE included only water. Monomer peaks were largely those of HEMA with lower levels of phosphate monomers. OBFL/CFSE adhesive model spectra suggested that both contained equal volumes of Bis-GMA/HEMA, with CFSE having 10-MDP. Filler levels and spectra from OBFL (48 wt.%) and CFSE (5 wt.%) were different. Both systems reached a 50% conversion rate within seconds of light exposure. The final conversion for OBFL (74 ± 1%) was lower compared to CFSE (79 ± 2%) (p < 0.05). ATR-FTIR is a useful method to investigate relative levels of main components in bonding systems and their polymerisation kinetics. Such information is valuable to understanding such behaviour.

scholarly journals Action of mouthwashes on Staphylococcus spp: isolated in the saliva of community and hospitalized individuals

2009 ◽  
Vol 45 (3) ◽  
pp. 551-557 ◽  
Author(s):  
Denise de Andrade ◽  
Paula Regina de Souza ◽  
Carolina Contador Beraldo ◽  
Evandro Watanabe ◽  
Mery Elen Lima ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Chloride Solution ◽  
Cetylpyridinium Chloride ◽  
Strain Identification ◽  
Diverse Range ◽  
Significance Level ◽  
Hospital Patients ◽  
Saliva Collection ◽  
Critical Patients ◽  
Staphylococcus Spp

The use of mouthwashes in critical patients has been a source of concern for health professionals due to the diverse range of products, causing uncertainty about which is the most indicated. This study aimed to assess the susceptibility of Staphylococcus spp. isolated in the saliva of individuals from the community and patients in Intensive Care Units (ICU) as to antiseptic mouthwashes. The following oral antiseptics were assessed: cetylpyridinium chloride solution, Listerine® and Neen®. Calcium alginate swab was used for saliva collection to isolate Staphylococcus spp. Microbiological processing involved growth, isolation, strain identification and determination of MID (maximum inhibitory dilution). MID was considered the greatest dilution that completely inhibited the strains. The products efficacy was analyzed by a two-factor ANOVA repeated measures and by Bonferroni adjustments in multiple comparisons, considering a significance level of α=0.05. In total, 80 strains of Staphylococcus spp. were isolated, 40 from ICU patients and 40 from community individuals. MID results revealed that cetylpyridinium chloride solution presented better results in comparison to other products, that is, 39 (97.5%) strains from hospital patients with MID 1:128, and 37 (92.5%) of individuals from the community had MID 1:64. Neen® inhibited all strains in both groups at a dilution from 1:2 to 1:4. Listerine® presented the worst MID results, 65% of the strains from individuals from the community and 10% of hospital strains were not inhibited at a dilution of 1:2.

The Effects of Superficial Heating before 1-MHz Ultrasound on Tissue Temperature

2003 ◽  
Vol 12 (2) ◽  
pp. 95-103 ◽  
Author(s):  
William R. Holcomb ◽  
Chris Blank
Keyword(s):  
Athletic Training ◽  
Repeated Measures ◽  
Outcome Measure ◽  
Tissue Temperature ◽  
Temperature Elevation ◽  
Main Outcome Measure ◽  
Cooling Period ◽  
Dependent Variables ◽  
Within Subjects ◽  
Independent Variable

Context:Ultrasound significantly raises tissue temperature, but the time of temperature elevation is short.Objective:To assess the effectiveness of superficial preheating on temperature elevation and decline when using ultrasound.Design:Within-subjects design to test the independent variable, treatment condition; repeated-measures ANOVAs to analyze the dependent variables, temperature elevation and decline.Setting:Athletic training laboratory.Intervention:Temperature at a depth of 3.75 cm was measured during ultrasound after superficial heating and with ultrasound alone.Subjects:10 healthy men.Main Outcome Measure:Temperature was recorded every 30 s during 15 min of ultrasound and for 15 min afterward.Results:Temperature elevation with ultrasound was significantly greater with preheating (4.0 ± 0.21 °C) than with ultrasound alone (3.0 ± 0.22 °C). Temperature decline was not significantly different between preheating and ultrasound alone.Conclusions:Superficial preheating significantly increases temperature elevation but has no effect on temperature decline during a 15-min cooling period.

data a; * significance level; a=0.05; * variance of difference of two observations on the log scale; * sigmaW = within-subjects standard deviation; sigmaW=0.355; s=sqrt(2)*sigmaW; * total number of subjects (needs to be a multiple of 2); n=58; * error degrees of freedom for AB/BA cross-over with n subjects in total; n2=n-2; * ratio = mu_T/mu_R; ratio=1.00; run; data b; set a; * calculate power; t1=tinv(1-a,n-2); t2=-t1; nc1=(sqrt(n))*((log(ratio)-log(0.8))/s); nc2=(sqrt(n))*((log(ratio)-log(1.25))/s); df=(sqrt(n-2))*((nc1-nc2)/(2*t1)); prob1=probt(t1,df,nc1); prob2=probt(t2,df,nc2); answer=prob2-prob1; power=answer*100; run; proc print data=b; run; As an example of using this SAS code, suppose µ = 1, σ = 0.355, α = 0.05 and n = 58. The power (as a percentage) is calculated as 90.4. The required number of subjects to achieve a given power can easily be obtained by trial and error using a selection of values of n. An alternative approach is to use trial and error directly on the sample size n for a given power. For more on this see Phillips (1990) and Diletti et al. (1991), for example. 7.4 Individual bioequivalence As noted in Section 7.1, individual bioequivalence (IBE) is a criterion for deciding if a patient who is currently being treated with R can be

2003 ◽  
pp. 362-362
Keyword(s):  
Standard Deviation ◽  
Sample Size ◽  
Degrees Of Freedom ◽  
Trial And Error ◽  
Significance Level ◽  
Individual Bioequivalence ◽  
Alternative Approach ◽  
Within Subjects ◽  
Log Ratio ◽  
Selection Of

scholarly journals Effect of Chlorhexidine and Ethanol Application on Longterm Push-out Bond Strength of Fiber Posts to Dentin

2015 ◽  
Vol 16 (7) ◽  
pp. 547-553 ◽  
Author(s):  
Roberta Tarkany Basting ◽  
Cecília Pedroso Turssi ◽  
Flavia Lucisano Botelho do Amaral ◽  
Fabiana Mantovani Gomes França ◽  
Rafaela Crystyan Vaneli ◽  
...  
Keyword(s):  
Bond Strength ◽  
Repeated Measures ◽  
Adhesive System ◽  
Resin Cement ◽  
Control Group ◽  
Test Analysis ◽  
Significance Level ◽  
Fiber Posts ◽  
Etch And Rinse ◽  
Push Out

ABSTRACT Aim The aim of this study was to evaluate the effect of chlorhexidine and ethanol application on the push-out bond strength and bond durability of fiber posts cemented with an etch-and-rinse adhesive system/resin cement to intraradicular dentin. Materials and methods Fifty-four bovine roots were shaped for the cementation of a fiberglass post and received the application of 37% phosphoric acid. They were then randomly divided into three groups, according to the type of dentin treatment (n = 18) performed: no treatment (control group), 100% ethanol, or 2% chlorhexidine. Next, the adhesive system (Adper Scotch Bond Multipurpose Plus, 3M ESPE) was applied to the dentin, according to the manufacturer's instructions. Glass fiber posts were cemented with dual resin cement (Rely X ARC, 3M ESPE). After 48 hours, the specimens were serially sectioned for push-out test analysis, providing two slices from each root third (cervical, medium and apical), one of which was tested immediately and the other stored in distilled water for 180 days. The data were analyzed with three-way analysis of variance (ANOVA) for repeated measures and Tukey's test at a 5% significance level. Results Intraradicular treatment with chlorhexidine yielded the highest bond strength means, followed by ethanol treatment. The control group presented the lowest bond strength means. Water storage exerted no effect on bond strength values. Conclusion Both chlorhexidine and ethanol improved push-out bond strength to intraradicular dentin, with the former providing the best results, regardless of the storage time. Clinical significance The application of 2% chlorhexidine or 100% ethanol may be an important step that can be taken to enhance bond strength of fiber posts to intraradicular dentin, when dual resin cements are used. How to cite this article França FMG, Vaneli RC, de Melo Conti C, Basting RT, do Amaral FLB, Turssi CP. Effect of Chlorhexidine and Ethanol Application on Long-term Pushout Bond Strength of Fiber Posts to Dentin. J Contemp Dent Pract 2015;16(7):547-553.

scholarly journals Effects of Plyometric and Cluster Resistance Training on Explosive Power and Maximum Strength in Karate Players

2017 ◽  
Vol 6 (2) ◽  
pp. 34-44 ◽  
Author(s):  
Mohsen Aminaei ◽  
Sodabe Yazdani ◽  
Mohhamadreza Amirseifadini
Keyword(s):  
Resistance Training ◽  
Repeated Measures ◽  
Maximum Strength ◽  
Plyometric Training ◽  
Test Power ◽  
Significance Level ◽  
Cluster Group ◽  
Explosive Power ◽  
Post Test ◽  
Three Stages

The purpose of this study was to investigate the effects of plyometric and cluster resistance training on explosive power and maximum strength in karate players. Eighteen women, karate players (age mean ± SD 18.22 ± 3.02 years, mean height 163 ± 0.63cm, and mean body mass 53.25 ± 7.34 kg) were selected as volunteer samples. They were divided into two groups with respect to their recorded one repetition maximum squat exercise: [1] plyometric training (PT=9) and [2] Cluster training (CT=9) groups and performed a 9-week resistance training protocol that included three stages; [1] General fitness (2 weeks), [2] Strength (4 weeks) and [3] Power (3 weeks). Each group performed strength and power trainings for 7 weeks in stage two and three with owned protocol. The subjects were evaluated three times before stage one and after two and three stages for maximum strength and power. Data was analyzed using two way Repeated Measures (ANOVA) at a significance level of (P≤0.05). The statistical analysis showed that training stages on all research variables had a significant impact. The maximum strength of the pre-test, post-test strength and post-test power were in cluster group: 29.05 ± 1.54; 32.89 ± 2.80 and 48.74 ± 4.33w and in plyometric group were 26.98 ± 1.54; 38.48 ± 2.80 and 49.82 ± 4.33w respectively. The explosive power of the pre-test, post-test strength and post-test power in cluster group were 359.32±36.20; 427.91±34.56 and 460.55±36.80w and in plyometric group were 333.90±36.20; 400.33±34.56 and 465.20±36.80w respectively. However, there were not statistically significant differences in research variables between resistance cluster and plyometric training groups after 7 weeks. The results indicated both cluster and plyometric training program seems to improve physical fitness elements at the same levels.

scholarly journals Determination of Dental Adhesive Composition throughout Solvent Drying and Polymerization Using ATR–FTIR Spectroscopy

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3886
Author(s):  
Arwa Almusa ◽  
António H.S. Delgado ◽  
Paul Ashley ◽  
Anne M. Young
Keyword(s):  
Light Exposure ◽  
Light Emitting Diode ◽  
Attenuated Total Reflectance ◽  
Drying Time ◽  
Light Emitting ◽  
Spectral Changes ◽  
One Step ◽  
Urethane Dimethacrylate ◽  
Kinetics Of

The of this study aim was to develop a rapid method to determine the chemical composition, solvent evaporation rates, and polymerization kinetics of dental adhesives. Single-component, acetone-containing adhesives One-Step (OS; Bisco, USA), Optibond Universal (OU; Kerr, USA), and G-Bond (GB; GC, Japan) were studied. Filler levels were determined gravimetrically. Monomers and solvents were quantified by comparing their pure Attenuated Total Reflectance-Fourier Transform Infra-Red (ATR–FTIR) spectra, summed in different ratios, with those of the adhesives. Spectral changes at 37 °C, throughout passive evaporation for 5 min, then polymerisation initiated by 20 s, and blue light emitting diode (LED) (600 mW/cm2) exposure (n = 3) were determined. Evaporation and polymerisation extent versus time and final changes were calculated using acetone (1360 cm−1) and methacrylate (1320 cm−1) peaks. OS, OU, and GB filler contents were 0, 9.6, and 5.3%. FTIR suggested OS and OU were Bis-GMA based, GB was urethane dimethacrylate (UDMA) based, and that each had a different diluent and acidic monomers and possible UDMA/acetone interactions. Furthermore, initial acetone percentages were all 40−50%. After 5 min drying, they were 0% for OS and OU but 10% for GB. Whilst OS had no water, that in OU declined from 18 to 10% and in GB from 25 to 20% upon drying. Evaporation extents were 50% of final levels at 23, 25, and 113 s for OS, OU, and GB, respectively. Polymerisation extents were all 50 and 80% of final levels before 10 and at 20 s of light exposure, respectively. Final monomer polymerisation levels were 68, 69, and 88% for OS, OU, and GB, respectively. An appreciation of initial and final adhesive chemistry is important for understanding the properties. The rates of evaporation and polymerisation provide indications of relative required drying and light cure times. UDMA/acetone interactions might explain the considerably greater drying time of GB.

Object, Intensity and Subject Variables in Visual Evoked Response

1976 ◽  
Vol 43 (2) ◽  
pp. 532-534 ◽  
Author(s):  
James C. Norton
Keyword(s):  
Repeated Measures ◽  
Research Strategy ◽  
Intensity Analysis ◽  
Considerable Variability ◽  
Variable Stimulus ◽  
Visual Evoked Response ◽  
Independent Variables ◽  
Object Effect ◽  
Within Subjects ◽  
Subject Variables

10 subjects were studied to determine AEP effects of square, circle, and blank stimuli with variable stimulus intensity For the group as a whole, object and intensity effects were significant on a number of amplitude and latency measures, but the object effect appears largely to reflect the presence or absence of a figure, rather than its nature. Increased intensity differentially affected latency, shortening the first negative deflection while lengthening the second positive. Amplitude is generally increased with higher intensity. Analysis of within-subjects effects showed considerable variability as to which parameters were significantly related to the independent variables in individual subjects. A repeated-measures, within-subjects research strategy is seen as appropriate on the basis of these data.

Pairs of Latin Squares to Counterbalance Sequential Effects and Pairing of Conditions and Stimuli

1989 ◽  
Vol 33 (18) ◽  
pp. 1223-1227 ◽  
Author(s):  
James R. Lewis
Keyword(s):  
Human Factors ◽  
Repeated Measures ◽  
Random Sequence ◽  
Latin Square ◽  
Latin Squares ◽  
Sequential Effects ◽  
Long Run ◽  
Within Subjects ◽  
Human Factors Research

This paper discusses methods with which one can simultaneously counterbalance immediate sequential effects and pairing of conditions and stimuli in a within-subjects design using pairs of Latin squares. Within-subjects (repeated measures) experiments are common in human factors research. The designer of such an experiment must develop a scheme to ensure that the conditions and stimuli are not confounded, or randomly order stimuli and conditions. While randomization ensures balance in the long run, it is possible that a specific random sequence may not be acceptable. An alternative to randomization is to use Latin squares. The usual Latin square design ensures that each condition appears an equal number of times in each column of the square. Latin squares have been described which have the effect of counterbalancing immediate sequential effects. The objective of this work was to extend these earlier efforts by developing procedures for designing pairs of Latin squares which ensure complete counterbalancing of immediate sequential effects for both conditions and stimuli, and also ensure that conditions and stimuli are paired in the squares an equal number of times.

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