Contrast Ratio and Masking Ability of Three Ceramic Veneering Materials

2012 ◽  
Vol 37 (4) ◽  
pp. 406-416 ◽  
Author(s):  
NN Shono ◽  
HNA Al Nahedh
Keyword(s):  
Linear Regression Analysis ◽  
Contrast Ratio ◽  
Color Difference ◽  
Clinical Situation ◽  
Test Material ◽  
White Background ◽  
Mean Values ◽  
Black Background ◽  
Multiple Comparison Test ◽  
The Mean

SUMMARY Statement of the Problem Porcelain veneer materials are translucent and are therefore affected by their thickness as well as the color of the underlying substructure, which limits their masking ability and compromises the esthetic result in heavily stained teeth. Purpose The purpose of this study was to compare the contrast ratio (CR) and masking ability of three different veneering ceramics with two thicknesses by measuring the color differences over white and black backgrounds. Correlations between CR and masking ability of these veneering ceramics were evaluated. Methods and Materials A total of 30 disc-shaped specimens (12 mm diameter × 1.0 mm or 1.5 mm) were fabricated in shade A2 from three types of all-ceramic systems: IPS e.max Press (IPSe; Ivoclar Vivadent, Schaan, Liechtensein), Vita VM7 (VM7; VITA Zahnfabrik, Bad Säckingen, Germany), and Nobel Rondo Press Alumina: Solo (NRPA; Nobel Biocare, Zürich-Flughafen, Switzerland). The CR, defined as the ratio of illuminance (Y) of the test material when placed on the black background (Yb) to the illuminance of the same material when placed over a white background (Yw), was determined (CR=Yb/Yw). The color (CIE L*a*b*) and Y of each specimen were measured over standard white and black tiles using a spectrophotometer (ColorEye 7000 A, Model C6, GretagMacbeth, New Windsor, NY, USA). Masking abilities of the specimens were determined by measuring the color difference (ΔE) over white and black backgrounds. Both CR and ΔE data were analyzed using two-way analysis of variance (ANOVA). One-way ANOVA was used to compare the mean values of CR across the three materials followed by the Duncan multiple comparison test. The correlations between CR and ΔE were determined by comparing R2 values obtained from a linear regression analysis. A Student t-test for independent samples was used to compare the mean contrast ratio and ΔE values for the two thicknesses. Results CR values of NRPA were significantly less than those of IPSe and VM7, and the CR of IPSe was higher than that of VM7. Furthermore, CR increased as the thickness of the discs increased to 1.5 mm for all three materials. Mean ΔE values were significantly higher with 1.0-mm-thick discs than with 1.5-mm discs. Among the three materials it was observed that NRPA had the highest ΔE when compared with IPSe or VM7, whereas the ΔE of the latter two were not significantly different from one another. There was a strong linear correlation between CR and masking ability. Conclusion CR and masking ability are affected by the type as well as the thickness of the ceramic used. IPSe and VM7 are similar in their masking abilities, whereas NRPA had the lowest masking ability. NRPA was the most translucent, followed by VM7; IPSe was the most opaque. None of the materials tested was able to completely mask the black background. It is therefore recommended that the type of ceramic should be chosen according to each clinical situation.

How landscape and climate affect the spatial variability of the Italian rainfall extremes? Some initial clues based on I2-RED

2021 ◽  
Author(s):  
Paola Mazzoglio ◽  
Ilaria Butera ◽  
Pierluigi Claps
Keyword(s):  
Spatial Variability ◽  
Linear Regression Analysis ◽  
Alpine Region ◽  
Annual Rainfall ◽  
Mean Values ◽  
Rainfall Extremes ◽  
Geomorphological Parameters ◽  
The Mean ◽  
The Relationship ◽  
Italian Territory

<p>The intensity and the spatial distribution of precipitation depths are known to be highly dependent on relief and geomorphological parameters. Complex environments like mountainous regions are prone to intense and frequent precipitation events, especially if located near the coastline. Although the link between the mean annual rainfall and geomorphological parameters has received substantial attention, few literature studies investigate the relationship between the sub-daily maximum annual rainfall depth and geographical or morphological landscape features.<br>In this study, the mean of the rainfall extremes in Italy, recently revised in the so-called I<sup>2</sup>-RED dataset, are investigated in their spatial variability in comparison with some landscape and also some broad climatic characteristics. The database includes all sub-daily rainfall extremes recorded in Italy from 1916 until 2019 and this analysis considers their mean values (from 1 to 24 hours) in stations with at least 10 years of records, involving more than 3700 stations.<br>The geo-morpho-climatic factors considered range from latitude, longitude and minimum distance from the coastline on the geographic side, to elevation, slope, openness and obstruction morphological indices, and also include an often-neglected robust climatological information, as the local mean annual rainfall.<br>Obtained results highlight that the relationship between the annual maximum rainfall depths and the hydro-geomorphological parameters is not univocal over the entire Italian territory and over different time intervals. Considering the whole of Italy, the highest correlation is reached between the mean values of the 24-hours records and the mean annual precipitation (correlation coefficient greater than 0.75). This predominance remains also in sub-areas of the Italian territory (i.e., the Alpine region, the Apennines or the coastal areas) but correlation decreases as the time interval decreases, except for the Alpine region (0.73 for the 1-hour maximum). The other geomorphological parameters seem to act in conjunction, making it difficult to evaluate, with a simple linear regression analysis, their impact. As an example, the absolute value of the correlation coefficient between the elevation and the 1-hour extremes is greater than 0.35 for the Italian and the Alpine regions, while for the 24-hours interval it is greater than 0.35 over the coastal areas.<br>To further investigate the spatial variability of the relationship between rainfall and elevation, a spatial linear regression analysis has been undertaken. Local linear relationships have been fitted in circles centered on any of the 0.5-km size pixels in Italy, with 1 to 30 km radius and at least 5 stations included. Results indicate the need of more comprehensive terrain analysis to better understand the causes of local increasing or decreasing relations, poorly described in the available literature.</p>

The Influence of Dental Shade Guides and Experience on the Accuracy of Shade Matching

2016 ◽  
Vol 17 (1) ◽  
pp. 22-26 ◽  
Author(s):  
Mohammadreza Nakhaei ◽  
Jalil Ghanbarzadeh ◽  
Samin Alavi ◽  
Sahar Amirinejad ◽  
Hamidreza Rajatihaghi
Keyword(s):  
Calculated Data ◽  
Color Difference ◽  
Dental Students ◽  
Influential Factor ◽  
Color Measurement ◽  
Mean Values ◽  
Factors Affecting ◽  
Shade Matching ◽  
The Mean ◽  
Shade Guide

ABSTRACT Aim There is limited and inconsistent information on some factors affecting visual shade selection. The aim of this study was to evaluate the influence of shade guide type and professional experience on shade-matching results. Materials and methods Thirty Dental students (DS), 30 General dentists (GDs) and 30 Dental specialists (S) participated in this study. The participants were asked to match six target tabs using two dental shade guides: Vitapan Classical (VC) and Vitapan 3D-Master (3D). An intraoral spectrophotometer was used for color measurement of target tabs and selected tabs. The color difference (Conflict of interest: NoneE) values between the target tab and selected tab were calculated. Data were analyzed using analysis of variance (ANOVA) and paired t-test (α = 0.05). Results of the first five best matches for each target tab were expressed as ΔE1 to ΔE5. Differences in the mean values of ΔE1 to ΔE5 between VC and 3D were compared using descriptive statistics. Results There were no significant differences among the three participating groups in ΔE values when the 3D was used (p = 0.389). However, significant differences were found with VC (p < 0.001). The ΔE values achieved from the 3D were significantly lower than those from VC for DS and S (p = 0.001 and p < 0.001, respectively). For each of the first five best matches, the mean ΔE values from the 3D were smaller than the corresponding values of VC. Conclusion The type of dental shade guide affected the shadematching results. The level of experience was not found to be an influential factor in shade matching when 3D-Master shade guide was used. Clinical significance Compared with Vitapan Classical shade guide, use of the Vitapan 3D-Master shade guide improves shade-matching results. How to cite this article Nakhaei M, Ghanbarzadeh J, Amirinejad S, Alavi S, Rajatihaghi H. The Influence of Dental Shade Guides and Experience on the Accuracy of Shade Matching. J Contemp Dent Pract 2016;17(1):22-26.

scholarly journals The relationship between demographic features, anthropometric parameters, sleep duration, and physical activity with ECG parameters in Fasa Persian cohort study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alireza Mirahmadizadeh ◽  
Mojtaba Farjam ◽  
Mehdi Sharafi ◽  
Hossein Fatemian ◽  
Maryam Kazemi ◽  
...  
Keyword(s):  
Physical Activity ◽  
Cohort Study ◽  
Linear Regression ◽  
Sleep Duration ◽  
Linear Regression Analysis ◽  
Previous History ◽  
Multivariate Linear Regression Analysis ◽  
Mean Values ◽  
The Mean ◽  
The Relationship

Abstract Backgrounds Cardiovascular Diseases (CVDs) are the first leading cause of death worldwide. The present study aimed to investigate the relationship between demographics, anthropometrics, sleep duration, physical activity, and ECG parameters in the Fasa Persian cohort study. Methods In this cross-sectional study, the basic information of 10,000 participants aged 35–70 years in the Fasa cohort study was used. The data used in this study included demographic data, main Electrocardiogram (ECG) parameters, anthropometric data, sleep duration, and physical activity. Data analysis was performed using t-test, chi-square, and linear regression model. Results Based on multivariate linear regression analysis results, increased age was significantly associated with all study parameters. Nevertheless, gender and body mass index showed no significant relationship with SV3 and PR. Wrist circumference, hip circumference and waist circumference significantly increased the mean values of the ECG parameters. However, sleep duration was not significantly associated with the ECG parameters. In addition, hypertension was major comorbidity, which was shown to increase the mean values of the ECG parameters. Conclusion Several factors affected the ECG parameters. Thus, to interpret ECGs, in addition to age and gender, anthropometric indices, physical activity, and previous history of comorbidities, such as hypertension and ischemic heart disease, should be taken into consideration.

scholarly journals Effects of Background Color, Flash and Exposure Value on the Accuracy of Smartphone-Based Pill Recognition System Using Deep Convolutional Neural Network (Preprint)

2020 ◽  
Author(s):  
KyeongMin Cha
Keyword(s):  
Real World ◽  
Color Difference ◽  
Recognition System ◽  
Reference Image ◽  
White Background ◽  
Factors Affecting ◽  
The Real ◽  
Black Background ◽  
The Difference ◽  
World Image

BACKGROUND It is difficult to develop a drug image recognition system due to the difference of the pill color influenced by external environmental factors such as the illumination or presence of flash. OBJECTIVE In this study, we wanted to see how the difference in color between the reference image and the real-world image affects the accuracy in pill recognition under 12 real-world conditions according to the background colors, presence of flash, and exposure values (EV). METHODS We used 19 medications with different features of colors, shapes, and dosages. The average color difference was calculated based on the color distance between the reference image and the real-world image. RESULTS In the case of the black background, as the exposure value lowered, the accuracy of top-1 and top-5 increased independently of the presence of flash. The top-5 accuracy in black background increased from 26.8% to 72.6% with the flash on and from 29.5% to 76.8% with the flash off as EV decreased as well. On the other hand, top-5 accuracy was 62.1% to 78.4% in white background with the flash on. The best top-1 accuracy was 51.1 % in the white background, flash on, and EV+2.0. The best top-5 accuracy was 78.4% in the white background, flash on, and EV0. CONCLUSIONS The accuracy generally increased as the color difference decreased except in the case of black background and EV-2.0. This study reveals that the background colors, presence of flash, and exposure values in real-world conditions are important factors affecting the performance of a pill recognition model.

scholarly journals Spectrophotometric color evaluation of permanent incisors, canines and molars. A cross-sectional clinical study

2015 ◽  
Vol 88 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Ioana- Sofia Pop-Ciutrila ◽  
Horatiu Alexandru Colosi ◽  
Diana Dudea ◽  
Mandra Eugenia Badea
Keyword(s):  
Color Difference ◽  
Permanent Teeth ◽  
Cross Sectional ◽  
Mean Values ◽  
Color Coordinates ◽  
Color Differences ◽  
The Mean ◽  
Maxillary Incisors ◽  
Mean Differences ◽  
Acceptability Threshold

Background and aims. An accurate color reproduction represents the final validation level of an esthetic anterior or posterior restoration. The aim of this study was to evaluate the color of permanent maxillary incisors, canines and molars, using a clinical spectrophotometer.Methods. The Vita Easyshade Advance 4.0® intraoral spectrophotometer was used by one clinician to determine the color of 369 permanent maxillary incisors, canines and molars. The best matches to Vitapan Classical® and 3D-Master® shade guides were recorded. A one-way analysis of variance and Kruskal-Wallis test were used to compare L*, a*, b*, c* and h* color coordinates among the 3 types of teeth. Differences between the mean values of all color coordinates were evaluated by use of Bonferroni corrections. Color difference (ΔE*) between incisors, canines and molars was calculated from ΔL*, Δa* and Δb* data and the results were compared to ΔE*=3.3 acceptability threshold.Results. Except for Δa* and Δh* between canines and molars, statistically significant differences among the mean differences of all color coordinates were found when the 3 types of teeth were compared by pairs. The most frequently measured shades were A1 (48.4%), respectively 1M1 (31.5%) for incisors, B3 (36.6%), respectively 2M3 (39.8%) for canines and B3 (44.7%), respectively 2M3 (52%) for molars. Incisors had the highest lightness values, followed by canines and molars. Molars were the most chromatic with the highest a* and b* values.Conclusions. Despite the limitations of this study, color differences among incisors, canines and molars were found to be statistically significant, above the clinical acceptability threshold established. In conclusion, successful esthetic restorations of permanent teeth of the same patient need an individual color assessment and reproduction of every type of tooth. 

scholarly journals DETERMINATION OF DEPENDENCE OF CHEWELESS EFFECTS FROM TEMPERAMENT

2018 ◽  
pp. 47-50
Author(s):  
K.D. Toncheva ◽  
D.M. Korol ◽  
I.V. Zaporozhchenko ◽  
D.V. Kalashnikov ◽  
D.D. Kindii
Keyword(s):  
Alternative Hypothesis ◽  
Nervous Activity ◽  
Test Sample ◽  
Test Material ◽  
Statistical Relationship ◽  
Mean Values ◽  
Average Area ◽  
Masticatory Efficiency ◽  
Chewing Efficiency ◽  
The Mean

Introduction. Studies have shown that the style of each person's activity largely depends on the type of higher nervous activity entering the structure of his temperament. The temperament of an individual is considered innate, because it is a psychic property that does not lend itself to pedagogical correction and volitional regulation. Since the type of temperament affects the overall activity of the person, the idea arose to investigate the possibility of its influence on the work of the maxillofacial apparatus of young, healthy people. The aim of the work is to analyze the degree of dependence between chewing efficiency and human temperament with the help of the proposed improved method of chewing sampling. Materials and methods. The study, in which 59 people took part, of them 27 men (45.8%) and 32 women (54.2%) aged 17-25 years, was conducted on the basis of the laboratory of the Department of Propaedeutics of Orthopedic Dentistry of the HSEEU "Ukrainian Medical Stomatological Academy "(Poltava). The analysis of the obtained data showed absolute numerical superiority among the surveyed representatives of two temperamental groups: 1 group - sanguine, 17 of them 10 men and 7 women; 2 group - choleric people, 24 of them 9 men and 15 women. Samples for the chewing test were colloidal mass of agar-agar in the form of cylinders with a height of 10 and a diameter of 20 millimeters. All participants did 10 conventional chewing movements to grind the samples, after which all fragments of the test material were collected, washed, dried, the information was converted into photograph and was recorded in a computer base. Results. In the sanguine group, in determining the masticatory efficiency, the total number of fragments of the test sample ranged from 140.6 to 471.3, the average area of the fragments was 91.727 - 345.175 pxl2. In the choleric group, the total number of fragments of the test sample ranged from 194 to 644, and the average size of the fragments in the choleric group fluctuated 75.15 - 191.101 pxl2. The results of the study showed that representatives of the choleric group had a large total number of fragments of the test sample and a smaller average area. An increase in the number of fragments and a decrease in their area indicate a high masticatory efficiency, and therefore a better quality of chewing food, is observed in the choleric group. In the sanguine group, there is less total number of fragments and a larger average area compared to choleric, which indicates a lower chewing efficiency and, correspondingly, worse processing of food. Hypothesis (M0) on the absence of a statistical relationship between the parameters of the chewing test and a certain type of human temperament was developed. Accordingly, the alternative hypothesis (M1) relied on the assumption of a statistical relationship between these indicators. The obtained results did not allow rejecting the null hypothesis as when comparing the values of the total number of fragments and the mean values of these fragments. But, the confidence interval (0.052) of the mean fragment area values approaches the accepted critical level of significance (p = 0.05). Conclusions. Further statistical analysis showed that the numerical index of the average area of the chewing gum fragments is more reliable to a certain type of temperament in the experienced persons, which makes it possible to consider this parameter as a sensitive marker for assessing the condition of the dentoalveolar system in normal and pathological changes, including when determining the effectiveness of the orthopedic treatment.

scholarly journals Effects of Refractive Errors and Age on Binocular Function in Normal Adult Population

2020 ◽  
Author(s):  
Xiaodong Zhou ◽  
Man She ◽  
Tao Li ◽  
Qianqian Hu ◽  
Jie Zhu
Keyword(s):  
Adult Population ◽  
Linear Regression Analysis ◽  
Age Groups ◽  
Normal Adult ◽  
Comfort Zone ◽  
Mean Values ◽  
Binocular Function ◽  
The Mean ◽  
The Relationship ◽  
Vision Function

Abstract Purpose: To investigate the relationship between binocular function with gender, ages, and spherical equivalent (SE) .Methods: This observational study enrolled 243 healthy, non-strabismic adults, including 94 men and 149 women aged from 20 to 59 years. The subjects were divided into three groups according to SE: myopic group, emmetropic group and hyperopic group. The subjects were also divided into four groups according to age: 20-29 years group, 30-39 years group, 40-49 years group, and 50-59 years group. The binocular vision function was measured with a synoptophore, including subjective angle (SA), divergence, convergence and fusional vergence range (FVR). Results: The mean values of SA, divergence, convergence and range of fusion for the whole sample group were 3.33±0.16°, 9.72±0.26°, 19.34±0.54°, and 29.06±0.62°, respectively. The mean values of SA and divergence in myopic group were significantly larger than the emmetropic group (both p<0.05). SE, SA, divergence and FVR were significantly different among age groups (all p<0.05). Besides, linear regression analysis showed SE was correlated with SA and divergence (p=0.007, p=0.003). Age was correlated with SE, SA, divergence and FVR (p<0.001, p<0.001, p=0.005, p=0.002, respectively). In addition, the proportion of SA being in comfort zone (defined as the value of SA located in the middle 1/3 area of FVR) in age groups were statistically different. (χ2=8.283, p=0.041)Conclusion: Both SA and motor fusion are associated with age and SE in normal adult population.

scholarly journals Relationship between age, refractive errors and motor fusion in a normal Chinese adult population: a cross-sectional study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Man She ◽  
Tao Li ◽  
Qianqian Hu ◽  
Jie Zhu ◽  
Xiaodong Zhou
Keyword(s):  
Adult Population ◽  
Linear Regression Analysis ◽  
Age Groups ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Comfort Zone ◽  
Cross Sectional ◽  
Mean Values ◽  
Chinese Adult ◽  
The Mean

Abstract Background To investigate the relationships between motor fusion and sex, age and spherical equivalent (SE). Methods This observational study enrolled 243 healthy, nonstrabismic adults, including 94 men and 149 women aged 20 to 59 years. The subjects were divided into three groups according to SE: myopic, emmetropic and hyperopic groups. The subjects were also divided into four groups according to age: 20–29, 30–39, 40–49 and 50–59 years groups. Motor fusion was measured with a synoptophore, including subjective angle (SA), divergence, convergence and fusional vergence range (FVR). Results The mean values of divergence, convergence and FVR for the whole sample group were 9.72 ± 0.26°, 19.34 ± 0.54°, and 29.06 ± 0.62°, respectively. A higher value of divergence was found in the myopic group than in the emmetropic group (p < 0.05). SE and divergence were significantly different among age groups (all p < 0.05). In addition, linear regression analysis showed that SE was correlated with divergence (p = 0.003). Age was correlated with SE, divergence and FVR (p < 0.001, p = 0.005, p = 0.002, respectively). In addition, the proportion of SA being in the comfort zone (defined as the value of SA satisfying Percival’s criterion) in the age groups was significantly different (χ2 = 8.283, p = 0.041). Conclusions Motor fusion is associated with age and SE in the normal Chinese adult population.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

Comparative Study of Intranasal, Subcutaneous and Intravenous Administration of Desamino-D-Arginine Vasopressin (DDAVP)

1986 ◽  
Vol 55 (01) ◽  
pp. 108-111 ◽  
Author(s):  
M Köhler ◽  
P Hellstern ◽  
C Miyashita ◽  
G von Blohn ◽  
E Wenzel
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Factor Xii ◽  
Additional Advantage ◽  
Mean Values ◽  
Routes Of Administration ◽  
The Mean ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThis study was performed to evaluate the influence of different routes of administration on the efficacy of DDAVP treatment. Ten healthy volunteers received DDAVP intranasally (i.n.), subcutaneously (s.c.) and intravenously (i.v.) in a randomized cross-over trial. Factor XII and high molecular weight (HMW)-kininogen levels increased only slightly after DDAVP administration. The mean increase of factor VIII: C was 3.1 (i. v.), 2.3 (s. c.), and 1.3 (i.n.) - fold over baseline. Ristocetin cofactor (von Willebrand factor antigen) increased 3.1 (2.5), 2.0 (2.3) and 1.2 (1.2) - fold over baseline mean values after i.v., s.c. and i.n. DDAVP, respectively. The half-disappearance time of factor VIII and von Willebrand factor (vWF) after DDAVP ranged from five (factor VIII: C) to eight hours (vWF). The mean increase of fibrinolytic activity was more pronounced after i.v. DDAVP. The antidiuretic effect was moderate with no apparent differences between the routes of application. This study provides further evidence that both i.v. and s.c. DDAVP administration result in an appropriate and reliable stimulation of haemostasis. An additional advantage of s. c. administration is its suitability for home treatment.

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