Impact of Material Shade and Distance from Light Curing Unit Tip on the Depth of Polymerization of Composites

Abstract This study aimed to evaluate the effect of the composite shade and distance from the light-curing unit (LCU) tip on the irradiance reaching the bottom of composite disks and on the depth of polymerization. Composites of three shades (opaque - OXDC, bleach - BXL, and A2) were inserted into molds with 3-mm of thickness positioned over a spectrometer and photo-activated with the LCU (Bluephase) tip placed at 0 or 1 cm from the composite surface. The mean irradiance reaching the bottom of composite was recorded during the entire photo-activation (30 s). Specimens (2 x 2 x 4 mm) were polymerized and used to map the degree of conversion achieved in different depths from irradiated surface. Specimens were sectioned into slices that were positioned over the platform of the infra-red microscope connected to the spectrometer to map the conversion. The conversion was measured in eight different depths every 500-µm. Increasing the distance of LCU tip reduced the irradiance only for A2. Interposing OXDC disks resulted in lowest values of irradiance and A2 the highest one. A tendency to decrease the conversion was observed towards the bottom of specimens for all experimental conditions, and the slope was more accentuated for OXDC. Differences among shades and distances from LCU tip were evident only beyond 1.5-2.0 mm of depth. In conclusion, both composite shade and distance from LCU tip might affect the light-transmission and depth of polymerization, while the effect of last was more pronounced.

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Effects of delivering the same radiant exposures at 730, 1450, and 2920 mW/cm2 to two resin-based composites

European Journal of Dentistry ◽

10.4103/ejd.ejd_270_16 ◽

2017 ◽

Vol 11 (01) ◽

pp. 022-028 ◽

Cited By ~ 3

Author(s):

Maan M. AlShaafi

Keyword(s):

Fourier Transform ◽

Degree Of Conversion ◽

Attenuated Total Reflectance ◽

Curing Time ◽

Total Reflectance ◽

Metal Rings ◽

Significant Difference ◽

Light Curing ◽

Knoop Microhardness ◽

Different Depths

ABSTRACT Objective: To evaluate the effects of curing two resin-based composites (RBC) with the same radiant exposures at 730, 1450, and 2920 mW/cm2. Materials and Methods: Two types of RBC, Filtek Supreme Ultra and Tetric-EvoCeram-Bulk Fill, were light-cured to deliver the same radiant exposures for 5, 10, or 20 s by means of a modified Valo light emitted diode light-curing unit with the light tip placed directly over each specimen. The RBC was expressed into metal rings that were 2.0 and 4.0 mm in thickness, directly on an attenuated total reflectance Fourier transform infrared plate heated to 33°C, and the degree of conversion (DC) of the RBC was recorded. The specimens were then removed and the Knoop microhardness (KHN) was tested at both the bottom and the top of each specimen. The KHN was tested again after 24 h and 7 days of storage in the dark at 37°C and 100% humidity. The DC and KHN results were analyzed with Fisher's protected least significant difference at α = 0.05. Results: The DC values for the specimens cured at the three different irradiance levels were similar. However, at different depths, there were differences in the DC values. In general, there were no clear differences among the samples cured in the three different groups, and the KHN was always greater 24 h and 7 days later (P < 0.05). Conclusions: Despite the curing time, and as long as the samples were cured with the same radiant exposures, there were no significant effects on the DC and KHN of both RBCs.

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Measurements of Photo-Induced Changes in Conjugated Polymers

MRS Proceedings ◽

10.1557/proc-228-73 ◽

1991 ◽

Vol 228 ◽

Author(s):

Carleton H. Seager ◽

Michael B. Sinclair ◽

D. Mc Branch ◽

A. J. Heeger ◽

G. L. Baker

Keyword(s):

Absorption Spectra ◽

Light Transmission ◽

Pump Light ◽

General Shape ◽

Experimental Conditions ◽

Photothermal Deflection Spectroscopy ◽

Highly Sensitive ◽

Infra Red ◽

Transmission Measurements ◽

Induced Changes

ABSTRACTWe have used the highly sensitive technique of Photothermal Deflection Spectroscopy (PDS) to measure changes in the infra-red absorption spectra of MEHPPV, P3HT and Polydiacetylene-4BCMU induced by pumping these polymers with light above the π - π* transition energy. In contrast to previous chopped light transmission measurements of these effects, the PDS technique can directly measure the buildup or decay of the absorption coefficient, m, on the time scale of seconds to days. In the case of MEHPPV we observe that above-gap light causes the appearance of a broad infra-red peak in α, which continues to grow-in hours after the pump light is first applied. For this polymer the general shape of the absorption spectra in the unpumped state mimics the photo-induced changes, suggesting that remnant photo-induced states determine the maximum transparency observed under normal experimental conditions. For P3HT and to a lesser extent, MEHPPV, we also observe irreversible photo-induced absorption components which we tentatively identify with photo-induced oxidation of the polymer matrix.

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Comparison of silorane and methacrylate-based composite resins on the curing light transmission

Brazilian Dental Journal ◽

10.1590/s0103-64402010000600010 ◽

2010 ◽

Vol 21 (6) ◽

pp. 538-542 ◽

Cited By ~ 19

Author(s):

Ricardo Danil Guiraldo ◽

Simonides Consani ◽

Rafael Leonardo Xediek Consani ◽

Sandrine Bittencourt Berger ◽

Wilson Batista Mendes ◽

...

Keyword(s):

Composite Resin ◽

Light Transmission ◽

Knoop Hardness ◽

Composite Resins ◽

Power Meter ◽

Light Curing ◽

Curing Light ◽

The Mean ◽

Spectral Distributions ◽

The Difference

The aim of this study was to investigate the influence of different composite resins - Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) - on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25%) was significantly higher than that of Heliomolar (12%). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.

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Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites

Operative Dentistry ◽

10.2341/16-349-l ◽

2017 ◽

Vol 42 (5) ◽

pp. 537-547 ◽

Cited By ~ 19

Author(s):

CAK Shimokawa ◽

B Sullivan ◽

ML Turbino ◽

CJ Soares ◽

RB Price

Keyword(s):

Emission Spectrum ◽

Broad Spectrum ◽

Light Transmission ◽

High Irradiance ◽

Degree Of Conversion ◽

Single Peak ◽

Bottom Surface ◽

Light Conditions ◽

Violet Light ◽

Light Curing

SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm2) or high irradiance (3600 mW/cm2) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. Results: For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (p<0.05). The RBCs that included alternative photoinitiators had greater microhardness values at the top when cured with broad-spectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with single-peak blue lights. With the exception of the microhardness at the top of TPH, equivalent or higher microhardness and degree-of-conversion values were achieved at the bottom surface when the standard (1200 mW/cm2) irradiance levels were used compared to when high irradiance levels were used. Conclusions: Considering the different behaviors of the tested RBCs, the emission spectrum and irradiance level influenced the polymerization of some RBCs. The RBCs that included alternative photoinitiators produced greater values at the top when cured with broad-spectrum lights, while at the bottom, results were equal or higher for the RBCs photoactivated with single-peak blue lights.

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Effect of Simulated Pulpal Microcirculation on Temperature When Light Curing Bulk Fill Composites

Operative Dentistry ◽

10.2341/17-351-l ◽

2019 ◽

Vol 44 (3) ◽

pp. 289-301 ◽

Cited By ~ 4

Author(s):

SSL Braga ◽

LRS Oliveira ◽

MTH Ribeiro ◽

ABF Vilela ◽

GR da Silva ◽

...

Keyword(s):

Temperature Rise ◽

Light Transmission ◽

Resin Composite ◽

Exothermic Reaction ◽

Adhesive System ◽

Degree Of Conversion ◽

Pulp Chamber ◽

Significance Level ◽

Light Curing ◽

Lower Temperature

SUMMARY Objectives: To evaluate the effect of light curing bulk fill resin composite restorations on the increase in the temperature of the pulp chamber both with and without a simulated pulpal fluid flow. Methods and Materials: Forty extracted human molars received a flat occlusal cavity, leaving approximately 2 mm of dentin over the pulp. The teeth were restored using a self-etch adhesive system (Clearfil SE Bond, Kuraray) and two different bulk fill resin composites: a flowable (SDR, Dentsply) and a regular paste (AURA, SDI) bulk fill. The adhesive was light cured for 20 seconds, SDR was light cured for 20 seconds, and AURA was light cured for 40 seconds using the Bluephase G2 (Ivoclar Vivadent) or the VALO Cordless (Ultradent) in the standard output power mode. The degree of conversion (DC) at the top and bottom of the bulk fill resin composite was assessed using Fourier-Transform Infra Red spectroscopy. The temperature in the pulp chamber when light curing the adhesive system and resin composite was measured using a J-type thermocouple both with and without the presence of a simulated microcirculation of 1.0-1.4 mL/min. Data were analyzed using Student t-tests and two-way and three-way analyses of variance (α=0.05 significance level). Results: The irradiance delivered by the light-curing units (LCUs) was greatest close to the top sensor of the MARC resin calibrator (BlueLight Analytics) and lowest after passing through the 4.0 mm of resin composite plus 2.0 mm of dentin. In general, the Bluephase G2 delivered a higher irradiance than did the VALO Cordless. The resin composite, LCU, and region all influenced the degree of cure. The simulated pulpal microcirculation significantly reduced the temperature increase. The greatest temperature rise occurred when the adhesive system was light cured. The Bluephase G2 produced a rise of 6°C, and the VALO Cordless produced a lower temperature change (4°C) when light curing the adhesive system for 20 seconds without pulpal microcirculation. Light curing SDR produced the greatest exothermic reaction. Conclusions: Using simulated pulpal microcirculation resulted in lower temperature increases. The flowable composite (SDR) allowed more light transmission and had a higher degree of conversion than did the regular paste (AURA). The greatest temperature rise occurred when light curing the adhesive system alone.

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Does an additional UV LED improve the degree of conversion and Knoop Hardness of light-shade composite resins?

European Journal of Dentistry ◽

10.1055/s-0039-1698978 ◽

2012 ◽

Vol 06 (04) ◽

pp. 396-401 ◽

Cited By ~ 1

Author(s):

Maria Cecília Caldas Giorgi ◽

Flávio Henrique Baggio Aguiar ◽

Luís Luís Soares ◽

Airton Abrahão Martin ◽

Priscila Christiane Suzy Liporoni ◽

...

Keyword(s):

Knoop Hardness ◽

Surface Interaction ◽

Composite Resins ◽

Degree Of Conversion ◽

Third Generation ◽

Composite Surface ◽

Led Light ◽

Uv Led ◽

Significant Difference ◽

Light Curing

ABSTRACTObjective: The purpose of this study was to evaluate the degree of conversion (DC) using FTRaman spectroscopy and the Knoop hardness (KHN) of composites cured by second and third-generation LED light curing-units (LCU), Radii Cal and Ultralume 5.Methods: Three composites (Filtek Supreme XT, Filtek Z350, and Esthet X) were selected for this study. KHN testing (n=10) was performed with 10 indentations for the top (T) and bottom (B) surfaces. For DC (n=10), both the T and B surfaces were analyzed.Results: For KHN, the three composites differed in hardens. There was a “LCU-surface” interaction, in which Radii Cal showed significantly greater hardens in the B surface. For DC, there was a “composite-surface-LCU” interaction. For the “composite” factor, there was no significant difference between the groups, except for Supreme XT-Radii Cal (T or B surfaces). For the “LCU” factor there was a significant difference for Supreme XT T surface, Ultralume 5 obtained a higher DC. For the Z350 T surface, a significant difference in the DC in which Radii Cal obtained better results. For the “surface” factor, all groups presented T surfaces with a higher DC than the B surfaces, the sole exceptions involved Esthet X-Radii Cal and Z350-Ultralume 5.Conclusion: Knowledge regarding composite composition and the characteristics of LCUs are important for effective polymerization. (Eur J Dent 2012;6:396-401)

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Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

BioMed Research International ◽

10.1155/2016/5713962 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

E. Uusitalo ◽

J. Varrela ◽

L. Lassila ◽

P. K. Vallittu

Keyword(s):

Light Propagation ◽

Light Transmission ◽

Light Attenuation ◽

Specimen Thickness ◽

Average Thickness ◽

Moist Air ◽

Dentinal Tubules ◽

Light Curing ◽

Curing Light ◽

The Mean

Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation.Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n=5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars.Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2for enamel and 398 mW/cm2for dentin (p<0.05). The increase of the specimen thickness decreased light transmission in all groups (p<0.005), and moist specimens attenuated light less than air-dried specimens in all thicknesses (p<0.05). EDTA treatment increased light transmission from 398 mW/cm2to 439 mW/cm2(1 mm dentin specimen thickness) (p<0.05). Light transmission through intact premolar was 6.2 mW/cm2(average thickness 8.2 mm) and through incisor was 37.6 mW/cm2(average thickness 5.6 mm).Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert’s law.

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Degree of Conversion and Polymerization Shrinkage of Bulk-Fill Resin-Based Composites

Operative Dentistry ◽

10.2341/16-027-l ◽

2017 ◽

Vol 42 (1) ◽

pp. 82-89 ◽

Cited By ~ 23

Author(s):

P Yu ◽

AUJ Yap ◽

XY Wang

Keyword(s):

Light Emitting Diode ◽

Degree Of Conversion ◽

Attenuated Total Reflectance ◽

Polymerization Shrinkage ◽

Light Emitting ◽

Significant Difference ◽

Before And After ◽

Light Curing ◽

Curing Light ◽

The Mean

SUMMARY This study evaluated the degree of conversion (DC) and polymerization shrinkage (PS) of contemporary bulk-fill resin-based composites (RBCs) including giomer materials. Two giomer bulk-fill (Beautifil Bulk Restorative [BBR], Beautifil Bulk Flowable [BBF]), two nongiomer bulk-fill (Tetric N-Ceram Bulk-fill [TNB], Smart Dentin Replacement [SDR]), and three conventional non–bulk-fill (Beautifil II [BT], Beautifil Flow Plus [BF], Tetric N-Ceram [TN]) RBCs were selected for the study. To evaluate the DC, disc-shaped specimens of 5-mm diameter and 2-mm, 4-mm, and 6-mm thickness were fabricated using customized Teflon molds. The molds were bulk filled with the various RBCs and cured for 20 seconds using a light-emitting diode curing light with an irradiance of 950 mW/cm2. The DC (n=3) was determined by attenuated total reflectance Fourier transform infrared spectroscopy by computing the spectra of cured and uncured specimens. PS (n=3) was measured with the Acuvol volumetric shrinkage analyzer by calculating specimen volumes before and after light curing. The mean DC for the various materials ranged from 46.03% to 69.86%, 45.94% to 69.38%, and 30.65% to 67.85% for 2 mm, 4 mm, and 6 mm, respectively. For all depths, SDR had the highest DC. While no significant difference in DC was observed between depths of 2 mm and 4 mm for the bulk-fill RBCs, DC at 2 mm was significantly greater than 6 mm. For the conventional RBCs, DC at 2 mm was significantly higher than at 4 mm and 6 mm. Mean PS ranged from 1.48% to 4.26% for BBR and BF, respectively. The DC at 2 mm and PS of bulk-fill RBCs were lower than their conventional counterparts. At 4 mm, the DC of giomer bulk-fill RBCs was lower than that of nongiomer bulk-fill materials.

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

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.2303.630 ◽

1980 ◽

Vol 23 (3) ◽

pp. 630-645 ◽

Cited By ~ 7

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.

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Platelet Hypersensitivity in Acute Malaria (Plasmodium falciparum) Infection in Man

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653407 ◽

1981 ◽

Vol 46 (02) ◽

pp. 547-549 ◽

Cited By ~ 21

Author(s):

E M Essien ◽

M I Ebhota

Keyword(s):

Plasmodium Falciparum ◽

Malaria Infection ◽

Light Transmission ◽

Human Platelet ◽

Platelet Rich Plasma ◽

Wave Pattern ◽

Falciparum Infection ◽

Secondary Wave ◽

Control Subjects ◽

The Mean

SummaryDuring acute malaria infection, platelets in human platelet-rich plasma are hypersensitive to the addition of ADP between 1.0 uM and 5.0 uM, or adrenaline 0.11 uM as aggregating agents. The mean maximum aggregation amplitude (as % of light transmission) obtained from 8 subjects in response to added ADP (1.0 uM), 39.8 ± 27 (1SD), was significantly greater than the value in 6 controls (5.2±6.7 (1SD); t = 3, 51 P <0.005). A similar pattern of response was obtained with higher ADP concentrations (2.4,4.5 or 5.0 uM) in 22 patients and 20 control subjects (89.9±14.9% vs 77.8±16.5% (1SD) t = 2.45, P <0.02). Addition of 4.5 uM ADP to patient PRP usually evoked only a single aggregation wave (fused primary and secondary waves) while the typical primary and secondary wave pattern was usually obtained from controls.Mean plasma B-thromboglobulin (BTG) concentration in 7 patients (208.3 ± 15.6 ng/ml) was significantly higher than the value in 6 control subjects (59.2±15.7 ng/ml; t = 13.44, P <0.002).

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