scholarly journals Cuspal deflection caused by dental composite polymerization shrinkage analyzed by digital holography

2021 ◽  
pp. 81-81
Author(s):  
Evgenije Novta ◽  
Tijana Lainovic ◽  
Dusan Grujic ◽  
Dejan Pantelic ◽  
Larisa Blazic
Keyword(s):  
Light Emitting Diode ◽  
Third Molar ◽  
Dental Composite ◽  
Polymerization Shrinkage ◽  
Light Emitting ◽  
Molar Teeth ◽  
Anderson Darling ◽  
Student’S T ◽  
Wall Group ◽  
Student’S T Test

Background/Aim. The objective of this study was to measure tooth cusps deflection caused by polymerization shrinkage of a resin-based dental material (RDM), in real-time using digital holographic interferometry (DHI), in two groups of cavities restored with and without an additional wall. Simultaneously, internal tooth mechanical behavior was monitored. Methods. Standardized three class I cavities were prepared on third molar teeth. The teeth were cut in two halves in the longitudinal plane, obtaining six samples for the study (now with class II cavities), divided into two groups (group G1 - with the additional wall, group G2 - without it) and mounted in aluminum blocks. The cavities were filled with the RDM, cured with a light emitting diode (LED) for 40 s from the occlusal direction, and monitored during the curing and post-curing period using DHI. Data were analyzed using student's t-test for independent samples and Anderson-Darling test, with an alpha level of 0.05. Results. At the end of the examined period, the samples from group G1 showed significantly increased tooth cusps deflection (t (10) = 4.7; p = 0.001) compared to samples from group G2. Conclusion. Within the limitations of this study, it was concluded that the presence of the additional wall simulating a dental matrix-band, influenced increased and prolonged tooth cusps deflection during the examined RDM polymerization shrinkage.

Physical–mechanical evaluation of a microhybrid and a nanofilled composite light activated by quartz-halogen tungsten and light-emitting diode

2018 ◽  
Vol 53 (7) ◽  
pp. 981-990
Author(s):  
Fernanda P Ritto ◽  
Eduardo Moreira da Silva ◽  
Hélio Rodrigues Sampaio-Filho ◽  
Raimundo A Lacerda ◽  
Márcio AP Borges ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Light Emitting Diode ◽  
Degree Of Conversion ◽  
Dental Composite ◽  
Polymerization Shrinkage ◽  
Light Emitting ◽  
Scanning Electron

The aim of this study was to characterize organic and disperse phase of a microhybrid (Mh – Filtek Z250) and a nanofilled (Nf – Filtek Z350) dental composite and analyze the influence of two LCUs (QHT-quartz-halogen tungsten and LED – light-emitting diode) on its physical–mechanical properties (degree of conversion, polymerization shrinkage, Vickers hardness and diametral tensile strength). Surface morphology was studied by scanning electron microscopy. The disperse phase content was measured using thermogravimetric analysis (TGA) and the organic fractions were qualitatively analyzed by nuclear magnetic resonance spectroscopy. Physical–mechanical properties were analyzed varying dental composite and LCU: Mh-QHT, Nf-QHT, Mh-LED and Nf-LED. The degree of conversion was evaluated using Raman spectrophotometry and polymerization shrinkage was measured by water picnometry. Mechanical behavior was analyzed by Vickers microhardness and diametral tensile testing. Scanning electron microscopy analysis showed similar microstructure of the materials mainly composed with different-sized particles dispersed within methacrylate matrix. Thermogravimetric analysis shows 80.13% of inorganic fraction for microhybrid composite and 75.29% for nanofilled. Nuclear magnetic resonance analysis showed similar organic structure for composites and did not show the presence of the monomer TEGDMA. Different light sources did not influence the tested properties, but considering different composites, nanofilled showed the highest degree of conversion (Gr 2:77%, Gr 4: 79.4%). The study shows that when the optimum radiant exposure (24 J/cm2) was used for polymerization of composites, regardless of the polymerization source, the properties of these resin materials showed satisfactory and similar results in relation to the conversion of polymers, polymerization shrinkage and mechanical behavior.

scholarly journals Polymerization shrinkage stress of composites photoactivated by different light sources

2009 ◽  
Vol 20 (4) ◽  
pp. 319-324 ◽  
Author(s):  
Fernanda de Carvalho Panzeri Pires de Souza ◽  
Brahim Drubi Filho ◽  
Luciana Assirati Casemiro ◽  
Lucas da Fonseca Roberti Garcia ◽  
Simonides Consani
Keyword(s):  
Light Emitting Diode ◽  
Testing Machine ◽  
Adhesive System ◽  
Composite Resins ◽  
Shrinkage Stress ◽  
Light Sources ◽  
Polymerization Shrinkage ◽  
Light Emitting ◽  
Halogen Light ◽  
Glass Rods

The purpose of this study was to compare the polymerization shrinkage stress of composite resins (microfilled, microhybrid and hybrid) photoactivated by quartz-tungsten halogen light (QTH) and light-emitting diode (LED). Glass rods (5.0 mm x 5.0 cm) were fabricated and had one of the surfaces air-abraded with aluminum oxide and coated with a layer of an adhesive system, which was photoactivated with the QTH unit. The glass rods were vertically assembled, in pairs, to a universal testing machine and the composites were applied to the lower rod. The upper rod was placed closer, at 2 mm, and an extensometer was attached to the rods. The 20 composites were polymerized by either QTH (n=10) or LED (n=10) curing units. Polymerization was carried out using 2 devices positioned in opposite sides, which were simultaneously activated for 40 s. Shrinkage stress was analyzed twice: shortly after polymerization (t40s) and 10 min later (t10min). Data were analyzed statistically by 2-way ANOVA and Tukey's test (a=5%). The shrinkage stress for all composites was higher at t10min than at t40s, regardless of the activation source. Microfilled composite resins showed lower shrinkage stress values compared to the other composite resins. For the hybrid and microhybrid composite resins, the light source had no influence on the shrinkage stress, except for microfilled composite at t10min. It may be concluded that the composition of composite resins is the factor with the strongest influence on shrinkage stress.

scholarly journals Canal Centring Ability of ProTaper and Mtwo Rotary Systems in Curved Canals

2014 ◽  
Vol 18 (2) ◽  
pp. 89-92
Author(s):  
Dilek Erbay Turkaydin ◽  
Mahir Gunday ◽  
Hesna Sazak Ovecoğlu ◽  
Yıldız Garıp
Keyword(s):  
Apical Part ◽  
Apical Region ◽  
Root Canals ◽  
Mandibular Molar ◽  
Molar Teeth ◽  
Stereo Microscope ◽  
Group 3 ◽  
Group 2 ◽  
Student’S T ◽  
Student’S T Test

SUMMARYThe purpose of this investigation was to compare centring ratio of ProTaper and Mtwo rotary systems. 60 mandibular molar teeth which had 25, 30 and 35 degree curvature in mesio-buccal root canal were used. Group 1 had 25°, Group 2 had 30°, and Group 3 had 35° curvatures. The roots were sectioned horizontally at 2 mm away from the apex. The apical region was then observed under a stereo-microscope. In each group, teeth were instrumented using ProTaper and Mtwo systems. After canal preparation, digital images of apical part of canals were taken. These images were then superimposed by using Adobe Photoshop CS2 programme. The data were analyzed using ANOVA and Student’s t-test.No significant differences were found between each curvature degrees and rotary systems at the apical part of curved root canals (p<0.05).

scholarly journals Dental composite depth of cure with halogen and blue light emitting diode technology

BDJ ◽  
1999 ◽  
Vol 186 (8) ◽  
pp. 388-391 ◽  
Author(s):  
R W Mills ◽  
K D Jandt ◽  
S H Ashworth
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Dental Composite ◽  
Light Emitting ◽  
Depth Of Cure

scholarly journals The Effect of Different Shades, Voltages and Increment Thickness on the Polymerization Depth of a Microhybrid Composite

2012 ◽  
Vol 2 (2) ◽  
pp. 52-56
Author(s):  
Farhan Raza Khan ◽  
Muhammad Hasan ◽  
Syed Iqbal Azam
Keyword(s):  
Composite Material ◽  
Linear Regression ◽  
Developing World ◽  
Dental Composite ◽  
P Value ◽  
Depth Of Cure ◽  
Variable Voltage ◽  
The Mean ◽  
Student’S T ◽  
Student’S T Test

ABSTRACT Aim Electric fluctuations in the developing world are common and may affect dental composite curing. We determined the effect of variable voltage and increasing thickness of different shades of composite on its depth-of-cure. Materials and methods ISO scrapping method was used on 14 commonly used shades of Esthet-X HD composites. Student's t-test and ANOVA were applied to compare the mean depth-of-cure and a linear regression model was developed using variables voltage (180 V and 220 V), material thickness (2, 4 and 6 mm) and shades (n = 14). Results The mean curing depth of samples was significantly reduced at 180 volts compared to 220 volts (p-value <0.002). At thickness of 2 mm, all samples were fully cured but when it was raised to 4 mm, the depth-of-cure reduced to 1.86 mm ± 0.06; while at 6 mm thickness, it reached to 1.96 mm ± 0.06 (p-value < 0.001). Conclusion Around 82% variation in the depth-of-cure is explained by voltage, thickness and shade of composite material (p-value <0.001). Clinical significance Electric fluctuations are prevalent in the developing world and thus poor voltage flow is responsible for dental composite's inadequate polymerization. How to cite this article Khan FR, Hasan M, Azam SI. The Effect of Different Shades, Voltages and Increment Thickness on the Polymerization Depth of a Microhybrid Composite. Int J Prosthodont Restor Dent 2012;2(2):52-56.

Permanent teeth eruption chronology in a peruvian indigenous population

2018 ◽  
Vol 16 (1) ◽  
pp. 41
Author(s):  
Marisel Roxana Valenzuela-Ramos
Keyword(s):  
Descriptive Analysis ◽  
Cross Sectional Study ◽  
Permanent Teeth ◽  
Cross Sectional ◽  
Second Molar ◽  
Molar Teeth ◽  
Student’S T ◽  
The Right ◽  
Student’S T Test ◽  
Program Version

Objective: The objective of this study was to determine the chronology of the eruption of permanent teeth ina Peruvian indigenous population.Materials and Methods: This is a cross-sectional study with a sample of 1,644 children of ages between 5 and16 years old (804 girls and 840 boys), who underwent an oral examination to determine in which eruption phasetheir teeth were. The statistical analysis was performed using the SPSS program, version 21. The statistical testsused were Student’s t-test for independent samples, depending on the normality and homoscedasticity tests.Results: A descriptive analysis shows that the upper left and lower right first molars erupted at 6.98 years oldand 6.99 years old, respectively, and the last tooth to erupt was the upper right second molar at 11.91 years old.Conclusion: The first tooth to erupt was the first molar (upper and lower), while the last tooth to erupt wasthe upper second molar. Teeth erupt earlier on girls. Teeth erupt simultaneously both on the right and left sides.Also, teeth erupt in the jawbone earlier than in the maxilla.

Dental composite depth of cure with halogen and blue light emitting diode technology

BDJ ◽  
1999 ◽  
Vol 186 (8) ◽  
pp. 388-391 ◽  
Author(s):  
R. Mills ◽  
K. Jandt ◽  
S. Ashworth
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Dental Composite ◽  
Light Emitting ◽  
Depth Of Cure
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