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

2017 ◽  
Vol 42 (1) ◽  
pp. 82-89 ◽  
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.

scholarly journals Microhardness of resin-based materials polymerized with LED and halogen curing units

2005 ◽  
Vol 16 (2) ◽  
pp. 98-102 ◽  
Author(s):  
Daniela Francisca Gigo Cefaly ◽  
Giovano Augusto de Oliveira Ferrarezi ◽  
Celiane Mary Carneiro Tapety ◽  
José Roberto Pereira Lauris ◽  
Maria Fidela de Lima Navarro
Keyword(s):  
Statistical Analysis ◽  
Light Emitting Diode ◽  
Surface Hardness ◽  
Bottom Surface ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Led Light ◽  
Significant Difference ◽  
Light Curing ◽  
Curing Light

The purpose of this study was to evaluate the microhardness of resin-based materials polymerized with a LED (light-emitting diode) light-curing unit (LCU) and a halogen LCU. Twenty cylindrical specimens (3.0 mm in diameter and 2.0 mm high) were prepared for each tested material (Z100, Definite and Dyract). Specimens were light-cured with two LCUs (Ultraled and Curing Light 2500) for either 40 or 60 s on their top surfaces. Hardness was measured on top and bottom surfaces of each specimen. Statistical analysis was done by ANOVA and Tukey's test (p<0.05). There was no significant difference in hardness between LED LCU and halogen LCU for Z100 and Dyract on top surface. Conversely, lower hardness was recorded when Definite was light-cured with the LED LCU than with the halogen lamp. On bottom surface, hardness was significantly lower for all materials light-cured with LED LCU. Z100 was harder than Dyract and Definite regardless of the light curing unit. There was no significant difference in hardness between the exposure times on top surface. Higher hardness was obtained when the materials were light-cured for 60 s on bottom surface. The tested LED was not able to produce the same microhardness of resin-based materials as the halogen LCU.

scholarly journals Degree of conversion of adhesive systems light-cured by LED and halogen light

2007 ◽  
Vol 18 (1) ◽  
pp. 54-59 ◽  
Author(s):  
Cesar Augusto Galvão Arrais ◽  
Fenelon Martinho Pontes ◽  
Luis Presley Serejo dos Santos ◽  
Edson Roberto Leite ◽  
Marcelo Giannini
Keyword(s):  
Light Emitting Diode ◽  
Adhesive System ◽  
Degree Of Conversion ◽  
Infrared Analysis ◽  
Adhesive Systems ◽  
Light Emitting ◽  
Halogen Light ◽  
Etch And Rinse ◽  
Before And After ◽  
Light Curing

This study evaluated the effect of blue light emitting diode (LED) and quartz tungsten halogen (QTH) on the degree of conversion (DC) of an etch-and-rinse Single Bond adhesive system (SB) and a mixture composed of primer solution and resin bond from Clearfil SE Bond self-etching adhesive system (CB) using Fourier transform infrared analysis (FTIR). Adhesives were applied to potassium bromide pellet surfaces and FTIR analyses were performed before and after photo-activation for 10 s with either LED (Freelight 1 - 400 mw/cm²) or QTH (XL 3000 - 630 mw/cm²) light-curing units (n=8). Additional FTIR spectra were obtained from photo-activated samples stored in distilled water for 1 week. The DC was calculated by comparing the spectra obtained from adhesive resins before and after photo-activation. The results were analyzed by two-way split-plot ANOVA and Tukey's test (p<0.05). Both adhesive systems exhibited low DC (%) immediately after photo-activation (SB/QTH: 18.7 ± 3.9; SB/LED: 13.5 ± 3.3; CF/QTH: 13.6 ± 1.9; CF/LED: 6.1 ± 1.0). The DC of samples light-cured with LED was lower than DC of those light-cured with QTH, immediately after light curing and after 1 week (SB/QTH: 51.3 ± 6.6; SB/LED: 50.3 ± 4.8; CF/QTH: 56.5 ± 2.9; CF/LED: 49.2 ± 4.9). The LED curing unit used to photo-activate the adhesive resins promoted lower DC than the QTH curing unit both immediately after light curing and 1 week after storage in water.

scholarly journals Microleakage under Orthodontic Brackets Using High-Intensity Curing Lights

2009 ◽  
Vol 79 (1) ◽  
pp. 144-149 ◽  
Author(s):  
Mustafa Ulker ◽  
Tancan Uysal ◽  
Sabri Ilhan Ramoglu ◽  
Huseyin Ertas
Keyword(s):  
High Intensity ◽  
Light Emitting Diode ◽  
Bonferroni Correction ◽  
Light Emitting ◽  
Halogen Light ◽  
Halogen Light Source ◽  
Light Curing ◽  
Curing Light ◽  
High Intensity Light ◽  
Nail Varnish

Abstract Objective: To compare the microleakage of the enamel-adhesive-bracket complex at the occlusal and gingival margins of brackets bonded with high-intensity light curing lights and conventional halogen lights. Materials and Methods: Forty-five freshly extracted human maxillary premolar teeth were randomly separated into three groups of 15 teeth each. Stainless steel brackets were bonded in all groups according to the manufacturer's recommendations. Specimens (15 per group) were cured for 40 seconds with a conventional halogen light, 20 seconds with light-emitting diode (LED), and 6 seconds with plasma arc curing light (PAC). After curing, the specimens were further sealed with nail varnish, stained with 0.5% basic-fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage for the enamel-adhesive and bracket-adhesive interfaces from both the occlusal and gingival margins. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests with a Bonferroni correction. Results: The type of light curing unit did not significantly affect the amount of microleakage at the gingival or occlusal margins of investigated interfaces (P &gt;.05). The gingival sides in the LED and PAC groups exhibited higher microleakage scores compared with those observed on occlusal sides for the enamel-adhesive and adhesive-bracket interfaces. The halogen light source showed similar microleakage at the gingival and occlusal sides between both adhesive interfaces. Conclusions: High-intensity curing units did not cause more microleakage than conventional halogen lights. This supports the use of all these curing units in routine orthodontic practice.

scholarly journals The Influence of Distance on Radiant Exposure and Degree of Conversion Using Different Light-Emitting-Diode Curing Units

2019 ◽  
Vol 44 (3) ◽  
pp. E133-E144 ◽  
Author(s):  
AO Al-Zain ◽  
GJ Eckert ◽  
JA Platt
Keyword(s):  
Strong Correlation ◽  
Light Emitting Diode ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Degree Of Conversion ◽  
Light Emitting ◽  
Radiant Exposure ◽  
Light Curing ◽  
Irradiance Data ◽  
Resin Curing

SUMMARY Objectives: To investigate the influence of curing distance on the degree of conversion (DC) of a resin-based composite (RBC) when similar radiant exposure was achieved using six different light-curing units (LCUs) and to explore the correlation among irradiance, radiant exposure, and DC. Methods and Materials: A managing accurate resin curing-resin calibrator system was used to collect irradiance data for both top and bottom specimen surfaces with a curing distance of 2 mm and 8 mm while targeting a consistent top surface radiant exposure. Square nanohybrid-dual-photoinitiator RBC specimens (5 × 5 × 2 mm) were cured at each distance (n=6/LCU/distance). Irradiance and DC (micro-Raman spectroscopy) were determined for the top and bottom surfaces. The effect of distance and LCU on irradiance, radiant exposure, and DC as well as their linear associations were analyzed using analysis of variance and Pearson correlation coefficients, respectively (α=0.05). Results: While maintaining a similar radiant exposure, each LCU exhibited distinctive patterns in decreased irradiance and increased curing time. No significant differences in DC values (63.21%-70.28%) were observed between the 2- and 8-mm distances, except for a multiple-emission peak LCU. Significant differences in DC were detected among the LCUs. As expected, irradiance and radiant exposure were significantly lower on the bottom surfaces. However, a strong correlation between irradiance and radiant exposure did not necessarily result in a strong correlation with DC. Conclusions: The RBC exhibited DC values &gt;63% when the top surface radiant exposure was maintained, although the same values were not reached for all lights. A moderate-strong correlation existed among irradiance, radiant exposure, and DC.

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

2017 ◽  
Vol 11 (01) ◽  
pp. 022-028 ◽  
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.

scholarly journals Evaluation of the bond strength of orthodontic brackets and the degree of polymerisation and microhardness of an orthodontic adhesive using polyvawe light curing unit and varying light densities

2020 ◽  
Vol 23 (4) ◽  
pp. 9p
Author(s):  
Nuri Mert Topbasi ◽  
Yasin Atakan Benkli
Keyword(s):  
Bond Strength ◽  
Light Emitting Diode ◽  
Control Group ◽  
Bond Failure ◽  
Adhesive Resin ◽  
Mean Values ◽  
Light Emitting ◽  
Significant Difference ◽  
Light Curing

Objective: This study evaluates the shear bond strength (SBS) and Vickers micro-hardness (VHN) of the orthodontic adhesive resin Transbond XT using thermocycled samples. The study also measures the degree of cure by poliwave light curing unit Valo. Materials and Methods: 135 brackets were bonded for the SBS test, and 90 disc-shaped orthodontic adhesive resins were prepared for the VHN test. The measurements were taken either immediately or after 500 or 10.0000 thermocycling. The SBS and VHN test data were statistically evaluated using a Two-way ANOVA and Tukey multiple comparison tests. The degree of conversion (DC) was measured by FTIR. Results: The 10-sec polymerized control group (57.08) and the 10.000 termocycled samples (55.96) had the highest VHN scores. On the other hand, the 3 second polymerized and the 10.000 termocycled samples (39.22) had the lowest VHN scores. There was no significant difference in the bracket SBS values between the termocycled and immediate groups. An evaluation of the bond failure surfaces revealed that the ARI scores did not differ between the immediate and the thermo-cycled groups according to the power modes. The FTIR results revealed that the lowest DC was seen in the 3 second light-cured sample. Conclusion: Transbond XT provided sufficient bonding in terms of microhardness and DC under in vitro bracket bonding conditions after 10 and 8 seconds of Poliwave LED curing. However, low mean values were seen in the groups that received Poliwave LED curing for only 3 seconds. KEYWORDSARI score; FTIR; Light-Emitting Diode; Orthodontics; Thermocycling.

scholarly journals Impact of the light-curing source and curing time on the degree of conversion and hardness of a composite

2013 ◽  
Vol 1 (1) ◽  
pp. 91
Author(s):  
Anderson Catelan ◽  
Caetano Tamires ◽  
Boniek Castillo Dutra Borges ◽  
Giulliana Panfiglio Soares ◽  
Bruno de Castro Ferreira Barreto ◽  
...  
Keyword(s):  
Physical Properties ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
High Irradiance ◽  
Degree Of Conversion ◽  
Curing Time ◽  
Light Emitting ◽  
Light Curing ◽  
Ft Ir ◽  
The Impact

Adequate physical properties of the resinous materials are related to clinical longevity of adhesive restorations. The aim of this investigation was to assess the impact of light-curing source and curing time on the degree of conversion (DC) and Knoop hardness number (KHN) of a composite resin. Circular specimens (5 x 2 mm) were carried out (n = 7) of the Filtek Z250 (3M ESPE) composite. The specimens were light-cured by quartz-halogen-tungsten (QTH) XL 3000 (3M ESPE, 450 mW/cm2) or light-emitting diode (LED) Bluephase 16i (Vivadent, 1390 mW/cm2) for 20, 40, or 60 s. After 24 h, absorption spectra of composite were obtained using Spectrum 100 Optica (Perkin Elmer) FT-IR spectrometer in order to calculate the DC and, KHN was performed in the HMV-2T (Shimadzu) microhardness tester under 50-g load for 15 s dwell time. DC and KHN data were subjected to 2-way ANOVA and Tukey’s test at a pre-set alpha of 0.05. The LED showed highest DC and KHN values than QTH (p < 0.05). The increase of curing time improved the DC and KHN, all curing times with statistical difference (p < 0.05). The use of light-curing units with high irradiance and/or the time of cure increased may improve the physical properties of resin-based materials.

scholarly journals Real-Time Feedback of the Applied Light-Curing Technique and Its Impact on Degree of Conversion of Composite Restorations—A Study with Undergraduate Dental Students

2021 ◽  
Vol 11 (10) ◽  
pp. 1012
Author(s):  
Phoebe Burrer ◽  
Matej Par ◽  
Thomas Attin ◽  
Tobias T. Tauböck
Keyword(s):  
Real Time ◽  
Dental Students ◽  
Degree Of Conversion ◽  
Patient Simulator ◽  
Light Irradiance ◽  
Composite Restorations ◽  
Significant Difference ◽  
Before And After ◽  
Light Curing ◽  
And Training

The objective of this study was to investigate the effect of individual instructions and training of dental students on the amount of applied light irradiance before and after training using a patient simulator with integrated visual feedback. Furthermore, the effect on the degree of conversion of composite restorations placed by the dental students was assessed. Forty-two dental students, split into two groups, light-cured a simulated restoration in tooth 27 of a dental patient simulator for 20 s. The irradiance (mW/cm2) received by the detector was measured in real-time before and after individual instructions and training, and the energy delivered (J/cm2) was calculated for each student. The degree of conversion at the bottom of incrementally placed composite restorations prior to individual instructions (group 1) and after individual instructions (group 2) was assessed using Fourier-transform infrared (FTIR) spectroscopy. The irradiance and degree of conversion measurements were re-assessed after all students received individual instructions. Data were analyzed using Wilcoxon signed-rank test and Mann–Whitney U-test at an overall level of significance of ⍺ = 0.05. A significant increase (p < 0.001) in applied light irradiance could be observed after individual instructions for both groups, with notably reduced data scattering. However, no significant difference was detected for the degree of conversion of placed composite restorations before or after instruction and training. Neither gender nor age of the dental students affected the obtained results. Consistent light energy delivered by dental students could be achieved through individual instructions and training with a patient simulator, also leading to less scattered irradiance results. However, the improved light-curing performance after the training did not affect the degree of conversion of the placed class II composite restorations.

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