scholarly journals Effect of Thickness on Fluorescence of Some Clinical Dental Ceramics

2021 ◽  
Author(s):  
Sedighe Sadat Hashemikamangar ◽  
Sara Valizadeh ◽  
Alireza Mahmoudi Nahavandi ◽  
MasoomehHasani Tabatabaei ◽  
Marzieh Daryadar
Keyword(s):  
Technical Information ◽  
New Method ◽  
Dental Ceramics ◽  
Fluorescent Agent ◽  
Post Hoc

Objectives: This study aimed to develop a new method for measurement of florescence and compare the fluorescence of some clinical dental ceramics in different thicknesses. Materials and Methods: Forty-eight samples of feldspathic (Vita VM9, A2), IPS e.max (Ivoclar HT, A2), zirconia (Korox Zircostar, A2) and Enamic (Vita A2) ceramics were used in this study in 0.5 and 1 mm thicknesses. The fluorescence of the samples was measured by using a developed technique. The results were analyzed by two-way ANOVA and Duncan post-hoc test. P<0.05 was considered significant. Results: Enamic, feldspathic and e.max ceramics had significantly different fluorescence in descending order (P=0.000). Fluorescence of ceramics increased with an increase in their thickness from 0.5 to 1 mm (P=0.007). Conclusion: The results confirmed the applicability of the presented method for measurement of fluorescence of dental ceramics. While, the thickness of restoration determines the concentration of the fluorescent agent, some additional technical information is required for justification of the observed trend in the studied ceramics.

scholarly journals Variations in the Shades of Contemporary Dental Ceramics: An In Vitro Analysis

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1288
Author(s):  
Syed Rashid Habib ◽  
Abdulaziz Saud Al Rashoud ◽  
Turki Ali Safhi ◽  
Abdulrahman Hamad Almajed ◽  
Hamad Ali Alnafisah ◽  
...  
Keyword(s):  
Statistical Tests ◽  
Color Difference ◽  
Ceramic Materials ◽  
Dental Ceramics ◽  
Color Differences ◽  
Monolithic Zirconia ◽  
Vitro Analysis ◽  
Post Hoc ◽  
Shade Guide

Background: To identify and compare the shade variations of various commonly used esthetic dental ceramics by calculating their total-color-difference (ΔE) and translucency parameter (TP) using a spectrophotometer. Methods: In total, 165 disc specimens from three shades (A1, B1, and C1) of five ceramic materials (N = 55/shade; n = 11/ceramic material group) were prepared (Metal-ceramic (MC), IPS e.max press (Emax-P), IPS e.max layer (Emax-L), Layered Zirconia (Zr-L) and Monolithic zirconia (Zr-M)). With a spectrophotometer, the L*a*b* values were obtained. Total color differences (ΔE = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2) and translucency parameter (TP = [(L*B − L*W)2 + (a*B − a*W)2 + (b*B – b*W)2]1/2) were calculated. The statistical tests included ANOVA and Post hoc Tukey’s analysis (p < 0.05). Results: Significant differences (p = 0.000) were found between the groups for ΔE. Highest ΔE (A1) were found for Zr-L (80.18 ± 20) and lowest for Zr-M (62.97 ± 1.28). For B1, highest ΔE values were noted for MC (76.85 + 0.78) and lowest for the Emax-L (62.13 ± 1.49). For C1, highest ΔE values were found for the MC group (73.96 ± 0 67) and lowest for Emax-P (55.09 ± 1.76). Translucency variations between tested ceramics were revealed (p < 0.05). Highest TP values (A1) were found for Emax-L (2.99 ± 1.64) and lowest for Zr-L (0.35 ± 0.16). For B1, highest TP values were noted for Emax-P (3.50 ± 1.74) and lowest for MC (0.57 ± 0.40). For C1, highest TP values were found for Emax-P (4.46 ± 2.42) and lowest for MC (0.58 ± 0 48). Conclusions: Significant differences in ΔE and TP were found for tested ceramic groups. The color differences of the tested materials varied according to clinical acceptability, even with the selection of same color/shade. The color/shades of the various dental ceramics do not match with the vita shade guide tabs, to which they are compared most often. Shade differences are present between different lots of ceramic materials from the same or different brands.

scholarly journals Full throttle: Demonstrating the speed, accuracy, and validity of a new method for continuous two-dimensional self-report and annotation

2021 ◽  
Author(s):  
Kirill Fayn ◽  
Steven Willemsen ◽  
R. Muralikrishnan ◽  
Bilquis Castaño Manias ◽  
Winfried Menninghaus ◽  
...  
Keyword(s):  
Two Dimensions ◽  
Self Report ◽  
New Method ◽  
Future Research ◽  
Two Dimensional ◽  
One Dimensional ◽  
Fine Grained ◽  
Full Throttle ◽  
Post Hoc ◽  
Speed Accuracy

AbstractResearch on fine-grained dynamic psychological processes has increasingly come to rely on continuous self-report measures. Recent studies have extended continuous self-report methods to simultaneously collecting ratings on two dimensions of an experience. For all the variety of approaches, several limitations are inherent to most of them. First, current methods are primarily suited for bipolar, as opposed to unipolar, constructs. Second, respondents report on two dimensions using one hand, which may produce method driven error, including spurious relationships between the two dimensions. Third, two-dimensional reports have primarily been validated for consistency between reporters, rather than the predictive validity of idiosyncratic responses. In a series of tasks, the study reported here addressed these limitations by comparing a previously used method to a newly developed two-handed method, and by explicitly testing the validity of continuous two-dimensional responses. Results show that our new method is easier to use, faster, more accurate, with reduced method-driven dependence between the two dimensions, and preferred by participants. The validity of two-dimensional responding was also demonstrated in comparison to one-dimensional reporting, and in relation to post hoc ratings. Together, these findings suggest that our two-handed method for two-dimensional continuous ratings is a powerful and reliable tool for future research.

Stereolithography: A new method for processing dental ceramics by additive computer-aided manufacturing

2017 ◽  
Vol 33 (5) ◽  
pp. 477-485 ◽  
Author(s):  
Marion Dehurtevent ◽  
Lieven Robberecht ◽  
Jean-Christophe Hornez ◽  
Anthony Thuault ◽  
Etienne Deveaux ◽  
...  
Keyword(s):  
New Method ◽  
Dental Ceramics ◽  
Computer Aided Manufacturing ◽  
Computer Aided

Effect of newly Developed Resin Cements and Thermocycling on the Strength of Porcelain Laminate Veneers

2017 ◽  
Vol 18 (3) ◽  
pp. 209-213 ◽  
Keyword(s):  
Computer Aided Design ◽  
Artificial Aging ◽  
Testing Machine ◽  
Dental Ceramics ◽  
Cohesive Failure ◽  
Resin Cements ◽  
Luting Cements ◽  
Computer Aided ◽  
Post Hoc ◽  
Laminate Veneers

ABSTRACT Aim The aim of this study was to determine the effect of different luting cements and accelerated artificial aging (AAA) in the fracture resistance of porcelain laminate veneers (PLVs). Materials and methods A total of 80 disc-shaped specimens were prepared using computer-aided design/computer-aided milling technology from lithium disilicate glass-ceramic blocks. Specimens (0.5 mm thick, 10 mm diameter) were divided into eight groups of 10 specimens per group. The control groups consisted of specimens without cement and not subjected to AAA (CN group) and specimens prepared without cement but subjected to AAA (CW group). The experimental groups were subjected to AAA and cemented with Variolink Veneer, Variolink Esthetic LC, Variolink Esthetic DC, RelyX Unicem, RelyX Veneer, or RelyX Ultimate. Specimens were individually tested for biaxial flexure on a universal testing machine. One-way analysis of variance and the Tukey's post hoc test were used to compare the groups’ significance statistically (α = 0.05). Results The loads to fracture (LTF) values in the CN group were higher than those in the CW and experimental groups. The lowest LTF value was in the CW group (31.5 ± 9.5 N) and the highest LTF value in the CN group (56.7 ± 10.6 N). Tukey's post hoc test demonstrated a statistically significant (p < 0.01) difference between the CN group and the other groups. Conclusion Artificial aging had a significant effect on the LTF value of the tested specimens compared with the resin cements used. Cohesive failure within the PLVs was the most common mode of failure. Clinical significance Fatigue strength of dental ceramics and moisture was shown to affect the mechanical properties of allceramic restorations. All-ceramic material is extremely sensitive to humidity and thermocycling. How to cite this article Alqahtani FI. Effect of newly Developed Resin Cements and Thermocycling on the Strength of Porcelain Laminate Veneers. J Contemp Dent Pract 2017;18(3):209-213.

A New Method for Evaluating Thermal Compatibility of Multi-Layer Dental Ceramic Composites

2007 ◽  
Vol 330-332 ◽  
pp. 1401-1404
Author(s):  
Jun Cui ◽  
Jun Ou ◽  
Yong Lie Chao ◽  
Q.P. Gao ◽  
Guang Fu Yin ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Ceramic Materials ◽  
Ceramic Composites ◽  
New Method ◽  
Stepwise Multiple Regression ◽  
Thermal Shock Test ◽  
Dental Ceramics ◽  
Thermal Mismatch ◽  
Dental Ceramic ◽  
Thermal Compatibility

Dental ceramic materials do not always show linear expansion behavior. In general, thermal contraction behavior of dental porcelain can be described with the polynomial function: L/L= C+α1 T+α2 T2. In addition, a new method for taking into consideration of nonlinear contraction behavior of dental ceramics is proposed for calculating thermal mismatch value (α) between substrate and veneering materials. Discs of eight substrate/veneer combinations (n=10) were fabricated for thermal shock testing. In this study, a stepwise multiple regression analysis was performed to determine the relationship between thermal shock test results and thermal mismatch value (α) on these combinations. A high degree of correlation was found between αs-b and T. The new method proves to be a reliable one to predict thermal compatibility of multi-layer dental ceramic composites.

scholarly journals In vitro analysis of dental ceramics: evaluation of the radiopacity and chemical composition by raman spectroscopy

2018 ◽  
Vol 21 (2) ◽  
pp. 164
Author(s):  
Rodrigo Furtado De Carvalho ◽  
Fernando Luiz Goulart Cruz ◽  
Debora Pinto Antunes ◽  
Evane Gonçalves Toledo Júnior ◽  
Luiz Fernando Cappa De Oliveira ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Chemical Composition ◽  
Analysis Of Variance ◽  
Dental Ceramics ◽  
Restorative Dentistry ◽  
Digital Radiographs ◽  
Vitro Analysis ◽  
Post Hoc ◽  
In Vitro Analysis

<p><strong>Objective</strong>: This study compared the radiopacity of different ceramic systems by means of digital radiographs and evaluate the chemical composition of the samples by Raman spectroscopy. <strong>Material and Methods</strong>: The hypothesis tested was that there was a difference in radiopacity among the tested materials. Specimens were prepared for each ceramic tested: FLD - VM7 (VITA Zahnfabrik), LD - IPS Empress e.max Press (IPS Empress), AL - In Ceram Alumina (VITA Zahnfabrik), ALYZ - In Ceram Zirconia (VITA Zahnfabrik), YZ - Lava All Ceram (3M/ESPE), and MYZ - Zirconzahn (Talladium Brazil). The specimens were radiographed and submitted to radiographic density readings using a histogram tool. The spectrometer coupled to a petrographic microscope was used for Raman spectroscopy measurements. Analysis of variance (ANOVA) and a Tukey post-hoc test were used to compare radiopacity of the different materials. <strong>Results</strong>: For all tested materials, the radiopacity showed statistically significant differences, except YZ and MYZ. Lava All Ceram and ZirkonZahn had high radiopacity values and VM7 and IPS Empress e.max Press showed lower radiopacity than human dental structures. <strong>Conclusion</strong>: It was possible to conclude that radiopacity is closely linked to ceramic chemical composition.</p><p><strong>Keywords</strong></p><p>Dental ceramics; Radiopacity; Raman spectroscopy test; Restorative dentistry.</p>

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

The Link Between Verbal Short-Term Memory and Anomia Treatment Gains

2019 ◽  
Vol 28 (3) ◽  
pp. 1039-1052
Author(s):  
Reva M. Zimmerman ◽  
JoAnn P. Silkes ◽  
Diane L. Kendall ◽  
Irene Minkina
Keyword(s):  
Short Term Memory ◽  
Controlled Trial ◽  
Treatment Success ◽  
Linear Regression Models ◽  
Language Performance ◽  
Short Term ◽  
Term Memory ◽  
Treatment Gains ◽  
Post Hoc

Purpose A significant relationship between verbal short-term memory (STM) and language performance in people with aphasia has been found across studies. However, very few studies have examined the predictive value of verbal STM in treatment outcomes. This study aims to determine if verbal STM can be used as a predictor of treatment success. Method Retrospective data from 25 people with aphasia in a larger randomized controlled trial of phonomotor treatment were analyzed. Digit and word spans from immediately pretreatment were run in multiple linear regression models to determine whether they predict magnitude of change from pre- to posttreatment and follow-up naming accuracy. Pretreatment, immediately posttreatment, and 3 months posttreatment digit and word span scores were compared to determine if they changed following a novel treatment approach. Results Verbal STM, as measured by digit and word spans, did not predict magnitude of change in naming accuracy from pre- to posttreatment nor from pretreatment to 3 months posttreatment. Furthermore, digit and word spans did not change from pre- to posttreatment or from pretreatment to 3 months posttreatment in the overall analysis. A post hoc analysis revealed that only the less impaired group showed significant changes in word span scores from pretreatment to 3 months posttreatment. Discussion The results suggest that digit and word spans do not predict treatment gains. In a less severe subsample of participants, digit and word span scores can change following phonomotor treatment; however, the overall results suggest that span scores may not change significantly. The implications of these findings are discussed within the broader purview of theoretical and empirical associations between aphasic language and verbal STM processing.

A new method for the determination of nitrates

1960 ◽  
Vol 23 ◽  
pp. 227-232 ◽  
Author(s):  
P WEST ◽  
G LYLES
Keyword(s):  
New Method
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