scholarly journals Influence of light curing source on microhardness of composite resins of different shades

2006 ◽  
Vol 14 (1) ◽  
pp. 10-15 ◽  
Author(s):  
André Luiz Fraga Briso ◽  
Tânia Maria Fedel ◽  
Sibéria de Morais Pereira ◽  
Sílvio José Mauro ◽  
Renato Herman Sundfeld ◽  
...  
Keyword(s):  
Light Intensity ◽  
Confidence Level ◽  
Composite Resin ◽  
Composite Resins ◽  
The Other ◽  
Light Sources ◽  
Low Light ◽  
Tukey Test ◽  
Light Curing ◽  
Hardness Values

INTRODUCTION: The evolution of light curing units can be noticed by the different systems recently introduced. The technology of LED units promises longer lifetime, without heating and with production of specific light for activation of camphorquinone. However, further studies are still required to check the real curing effectiveness of these units. PURPOSE: This study evaluated the microhardness of 4 shades (B-0.5, B-1, B-2 and B-3) of composite resin Filtek Z-250 (3M ESPE) after light curing with 4 light sources, being one halogen (Ultralux - Dabi Atlante) and three LED (Ultraled - Dabi Atlante, Ultrablue - DMC and Elipar Freelight - 3M ESPE). METHODS: 192 specimens were distributed into 16 groups, and materials were inserted in a single increment in cylindrical templates measuring 4mm x 4mm and light cured as recommended by the manufacturer. Then, they were submitted to microhardness test on the top and bottom aspects of the cylinders. RESULTS: The hardness values achieved were submitted to analysis of variance and to Tukey test at 5% confidence level. It was observed that microhardness of specimens varied according to the shade of the material and light sources employed. The LED appliance emitting greater light intensity provided the highest hardness values with shade B-0.5, allowing the best curing. On the other hand, appliances with low light intensity were the least effective. It was also observed that the bottom of specimens was more sensitive to changes in shade. CONCLUSION: Light intensity of LED light curing units is fundamental for their good functioning, especially when applied in resins with darker shades.

scholarly journals Evaluation of the surface hardness of composite resins before and after polishing at different times

2006 ◽  
Vol 14 (3) ◽  
pp. 188-192 ◽  
Author(s):  
Michelle Alexandra Chinelatti ◽  
Daniela Thomazatti Chimello ◽  
Renata Pereira Ramos ◽  
Regina Guenka Palma-Dibb
Keyword(s):  
Statistical Analysis ◽  
Vickers Hardness ◽  
Composite Resin ◽  
Surface Hardness ◽  
Composite Resins ◽  
The Other ◽  
Test Results ◽  
Tukey Test ◽  
Natural Flow ◽  
Before And After

PURPOSE: The aim of this study was to evaluate the surface hardness of six composite resins: Revolution, Natural Flow, Fill Magic Flow, Flow-it! (flowables), Silux Plus (microfilled) and Z100 (minifilled) before and after polishing at different times. MATERIALS AND METHODS: For this purpose, 240 specimens (5mm diameter, 1.4mm high) were prepared. Vickers hardness was determined before and after polishing at different times: immediately, 24h, 7 and 21 days after preparation of the samples. Statistical analysis was performed by ANOVA and Tukey test. RESULTS: There was no difference in the hardness of flowable resins, which had lower hardness than the minifilled resin. The minifilled resin showed the highest surface hardness as compared to the other materials (p<0.01). All materials exhibited higher hardness after polishing, being more evident after 7 days. CONCLUSION: It may be concluded that, regardless of the composite resin, surface hardness was considerably increased when polishing was delayed and performed 1 week after preparation of the samples.

scholarly journals Evaluation of the Light Intensity Emitted by the Light-curing Devices of a Dental School Clinic in the North of Brazil: a Pilot Study

2021 ◽  
Vol 23 (1) ◽  
pp. 68-71
Author(s):  
José Henrique Nascimento Souza-Junior ◽  
André Farias Andrade ◽  
Luiz Evaristo Ricci Volpato ◽  
Mateus Rodrigues Tonetto ◽  
Aurélio Rosa da Silva Junior ◽  
...  
Keyword(s):  
Pilot Study ◽  
Light Intensity ◽  
Light Emission ◽  
Composite Resin ◽  
Composite Resins ◽  
Dental School ◽  
Polymerization Reaction ◽  
The North ◽  
Light Curing ◽  
Dental School Clinic

AbstractPhotoactivated composite resins are among the most widespread restorative materials in dentistry, particularly in cosmetic dentistry. To obtain the best properties of the material, the resins must have their polymerization reaction initiated by means of the light-curing device, which activates the photoinitiators present in the composites. For this process to occur in the desired way, it is essential that the light-curing device emits light at the intensity necessary to properly activate the photoinitiators. Thus, a pilot study was carried out to assess the light intensity emitted by the light-curing devices used in a school clinic. To assess the light intensity emitted by the devices, a radiometer was used. Twenty-four light-curing devices were evaluated, 13 Optilight Max devices, 8 Optilight LD MAX 440 devices, 3 Emitter C. devices. All the devices had an emitted light below 400 mW / cm² and 67% of the devices had intensity above 300 mW/cm². The average light emission values of the light-curing devices were Optilight Max 334mW/cm², Emitter C 275mW/cm², Optilight LD MAX 440 296mW/cm². It was concluded that no light-curing device emitted light at the recommended intensity (400 mW/cm²), two thirds of the devices emitted light in intensity above the minimum required for photopolymerization of composite resin increments of up to 2mm and one third emitted light in intensity below the required minimum. There was no difference among the light-curing device models tested in this study. Keywords: Photoinitiators, Dental. Dental. Tooth. Composite Resins. ResumoAs resinas compostas fotoativadas estão entre os materiais restauradores mais difundidos em odontologia, particularmente na odontologia estética. Para obtenção das melhores propriedades do material, as resinas precisam ter sua reação de polimerização iniciada por meio do fotopolimerizador, que ativa os fotoiniciadores presentes nos compósitos. Para que esse processo ocorra da forma desejada, é fundamental que o fotopolimerizador emita a luz na intensidade necessária para ativar adequadamente os fotoiniciadores. Assim, foi realizado um estudo piloto para avaliadar a intensidade da luz emitida pelo fotopolimerizadores utilizados em uma clínica-escola. Para avaliar a intensidade da luz emitida pelos dispositivos, foi utilizado um radiômetro. Vinte e quatro fotopolimerizadores foram avaliados, 13 aparelhos Optilight Max, 8 aparelhos Optilight LD MAX 440, 3 aparelhos Emitter C. Todos os dispositivos tiveram a luz emitida em intensidade inferior a 400 mW/cm² e 67% dos dispositivos apresentaram intensidade acima de 300 mW/cm². As médias de valores de emissão de luz dos fotopolimerizadores foram, Optilight Max 334mW/cm², Emitter C 275mW/cm², Optilight LD MAX 440 296mW/cm²Concluiu-se que nenhum fotopolimerizador emitiu luz na intensidade recomendada (400 mW/cm²), dois terços dos aparelhos emitiram luz em intensidade acima da mínima necessária para fotopolimerização de incrementos de resina composta de até 2mm e um terço emitiu luz em intensidade abaixo da mínima necessária. Não houve diferença entre os modelos de fotopolimerizador testados neste estudo. Palavras-chave: Fotoiniciadores Dentários. Dente. Resinas Compostas.

Influence of Hydrogen Peroxide Bleaching Gels on Color, Opacity, and Fluorescence of Composite Resins

2012 ◽  
Vol 37 (5) ◽  
pp. 526-531 ◽  
Author(s):  
CRG Torres ◽  
CF Ribeiro ◽  
E Bresciani ◽  
AB Borges
Keyword(s):  
Hydrogen Peroxide ◽  
Composite Resin ◽  
Color Change ◽  
Composite Resins ◽  
Control Group ◽  
Peroxide Bleaching ◽  
Color Changes ◽  
Tukey Test ◽  
Bleaching Gels ◽  
Bleaching Treatment

SUMMARY The aim of the present study was to evaluate the effect of 20% and 35% hydrogen peroxide bleaching gels on the color, opacity, and fluorescence of composite resins. Seven composite resin brands were tested and 30 specimens, 3-mm in diameter and 2-mm thick, of each material were fabricated, for a total of 210 specimens. The specimens of each tested material were divided into three subgroups (n=10) according to the bleaching therapy tested: 20% hydrogen peroxide gel, 35% hydroxide peroxide gel, and the control group. The baseline color, opacity, and fluorescence were assessed by spectrophotometry. Four 30-minute bleaching gel applications, two hours in total, were performed. The control group did not receive bleaching treatment and was stored in deionized water. Final assessments were performed, and data were analyzed by two-way analysis of variance and Tukey tests (p&lt;0.05). Color changes were significant for different tested bleaching therapies (p&lt;0.0001), with the greatest color change observed for 35% hydrogen peroxide gel. No difference in opacity was detected for all analyzed parameters. Fluorescence changes were influenced by composite resin brand (p&lt;0.0001) and bleaching therapy (p=0.0016) used. No significant differences in fluorescence between different bleaching gel concentrations were detected by Tukey test. The greatest fluorescence alteration was detected on the brand Z350. It was concluded that 35% hydrogen peroxide bleaching gel generated the greatest color change among all evaluated materials. No statistical opacity changes were detected for all tested variables, and significant fluorescence changes were dependent on the material and bleaching therapy, regardless of the gel concentration.

scholarly journals Does the temperature of beverages affect the surface roughness, hardness, and color stability of a composite resin?

2013 ◽  
Vol 07 (02) ◽  
pp. 165-171 ◽  
Author(s):  
Duygu Tuncer ◽  
Emel Karaman ◽  
Esra Firat
Keyword(s):  
Surface Roughness ◽  
Composite Resin ◽  
Color Change ◽  
Artificial Saliva ◽  
Color Stability ◽  
The Other ◽  
Control Group ◽  
Baseline Values ◽  
Hardness Values ◽  
Properties Of Composites

ABSTRACT Objective: To investigate the effect of beverages′ temperature on the surface roughness, hardness, and color stability of a composite resin. Materials and Methods: Fifty specimens of the Filtek Z250 composite (3M ESPE, Dental Products, St.Paul, MN, USA) were prepared and initial roughness, microhardness, and color were measured. Then the specimens were randomly divided into five groups of 10 specimens each: Coffee at 70°C, coffee at 37°C, cola at 10°C, cola at 37°C, and artificial saliva (control). After the samples were subjected to 15 min × 3 cycles per day of exposure to the solutions for 30 days, the final measurements were recorded. Results: After immersion in beverages, the artificial saliva group showed hardness values higher than those of the other groups (P < 0.001) and the microhardness values were significantly different from the initial values in all groups except for the control group. Both cola groups showed roughness values higher than the baseline values (P < 0.05), while the other groups showed values similar to the baseline measurements. When ΔE measurements were examined, the 70°C coffee group showed the highest color change among all the groups (P < 0.05). Conclusion: High-temperature solutions caused alterations in certain properties of composites, such as increased color change, although they did not affect the hardness or roughness of the composite resin material tested.

scholarly journals Effect of light-activation methods and water storage on the flexural strength of two composite resins and a compomer

2006 ◽  
Vol 20 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Leonardo Eloy Rodrigues Filho ◽  
Luis Antônio dos Santos Burger ◽  
Silvia Kenshima ◽  
José Roberto de Oliveira Bauer ◽  
Igor Studart Medeiros ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Composite Resin ◽  
Water Storage ◽  
Storage Period ◽  
Multiple Comparisons ◽  
Composite Resins ◽  
Activation Method ◽  
Light Activation ◽  
Tukey Test ◽  
Effect Of Light

The present study evaluated the flexural strength of three composite resins recommended for direct esthetic restorations: a polyacid modified composite (Dyract AP), a unimodal composite resin (Filtek Z250) and a hybrid composite resin (Point 4). The variation factors, apart from the type of composite resin, were the light activation method and the water storage period. The composite resins were light-cured in continuous mode (40 s, 500 mW/cm²) or in ramp mode (0-800 mW/cm² for 10 s followed by 30 s at 800 mW/cm²) and stored for 24 hours or 30 days in distilled water at 37°C. The data were analyzed by ANOVA and Tukey test for multiple comparisons (alpha = 0.05). The composite resin Z250 presented the highest mean flexural strength (166.74 MPa) and Dyract AP presented the lowest one (129.76 MPa). The storage for 30 days decreased the flexural strength in ramp mode (24 h: 156.64 MPa; 30 days: 135.58 MPa). The light activation method alone did not lead to different flexural strength values.

Some Effects of Temperature and Light on Floral Initiation and Development in Acacia pycnantha

1985 ◽  
Vol 12 (2) ◽  
pp. 109 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Light Intensity ◽  
Floral Development ◽  
Early Stage ◽  
The Other ◽  
Floral Initiation ◽  
Ambient Conditions ◽  
Low Light ◽  
Floral Primordia ◽  
Effects Of Temperature ◽  
Normal Light

Floral initiation and development in Acacia pycnantha were studied under three environments. Two had ambient southern Australian temperatures of warm summer (mean max. 32°C, mean min. 16°C) and cool winter (mean max. 19°C, mean min. 8°C), one with full sunlight (outside) and the other with 30% light intensity (shadehouse). The other environment (glasshouse) had slightly lower than normal light intensity and a relatively constant year round temperature of mean 28°C maximum and 16°C minimum. Plants were scored for microscopic and macroscopic evidence of floral initiation and development. Floral primordia were initiated all year round under all environments. Floral development proceeded normally under ambient conditions of temperature and light, and anthesis occurred between August and October. Under low light intensity, floral development did not progress beyond a very early stage and macroscopically visible racemes were rare. Under the constant temperatures, floral development proceeded normally up to the stage of microsporogenesis and megasporogenesis. Meiosis did not occur and inflorescence buds ceased growth and were shed from the plant. Plants were transferred between the outside and glasshouse conditions in June, at around the stage of meiosis. Those transferred from outside to the glasshouse did not flower whereas some of those transferred from the glasshouse to outside flowered, but later and for a shorter period than plants maintained outside throughout. It appears that a 70% reduction in sunlight inhibits floral development at an early stage and that temperatures of approximately mean maximum 19°C and minimum 8°C are required for meiosis in Acacia pycnantha.

scholarly journals Abrasion resistance of composites polymerized by light-emitting diodes (LED) and halogen light-curing units

2006 ◽  
Vol 17 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Janisse Martinelli ◽  
Fernanda de Carvalho Panzeri Pires-de-Souza ◽  
Luciana Assirati Casemiro ◽  
Camila Tirapelli ◽  
Heitor Panzer
Keyword(s):  
Surface Roughness ◽  
Mass Loss ◽  
Abrasion Resistance ◽  
Composite Resin ◽  
Composite Resins ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Halogen Light ◽  
Light Curing ◽  
Toothbrush Abrasion

This study compared the abrasion resistance of direct composite resins cured by light-emitting diodes (LED) and halogen light-curing units. Twenty specimens (12 mm in diameter; 1.0 mm thick) of each composite resin [TPH (Dentsply); Definite (Degussa); Charisma (Heraus Kulzer)] were prepared using a polytetrafluoroethylene matrix. Ten specimens per material were cured with the LED source and 10 with the halogen lamp for 40 s. The resin discs were polished, submitted to initial surface roughness reading (Ra initial - mum) in a roughness tester and stored in water at 37°C for 15 days. The specimens were weighed (M1) and submitted to simulated toothbrushing using slurry of water and dentifrice with high abrasiveness. After 100 minutes in the toothbrushing simulator, the specimens were cleaned, submitted to a new surface roughness reading (Ra final - mum) and reweighed (M2). Mass loss was determined as the difference between M1 and M2. Data were recorded and analyzed statistically by one-way ANOVA and Tukey Test at 5% significance level. The composite resin with greater size of inorganic fillers (TPH) showed the lowest mass loss and surface roughness means, indicating a higher resistance to toothbrush abrasion (p<0.05). Definite cured with LED presented the least resistance to toothbrush abrasion, showing the highest means of surface roughness and mass loss (p<0.05). The LED source did not show the same effectiveness as the halogen lamp for polymerizing this specific composite resin. When the composite resins were cured a halogen LCU, no statistically significant difference was observed among the materials (p>0.05). It may be concluded that the type of light-curing unit and the resin composition seemed to interfere with the materials' resistance to abrasion.

scholarly journals Effect of the increase of energy density on knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc

2005 ◽  
Vol 16 (3) ◽  
pp. 218-224 ◽  
Author(s):  
Américo Bortolazzo Correr ◽  
Mário Alexandre Coelho Sinhoreti ◽  
Lourenço Correr Sobrinho ◽  
Rubens Nisie Tango ◽  
Luis Felipe Jochims Schneider ◽  
...  
Keyword(s):  
Energy Density ◽  
Light Emitting Diode ◽  
Knoop Hardness ◽  
Composite Resins ◽  
Plasma Arc ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Light Curing ◽  
Cylindrical Cavities ◽  
Hardness Values

The aim of this study was to evaluate the effect of the increase of energy density on Knoop hardness of Z250 and Esthet-X composite resins. Cylindrical cavities (3 mm in diameter X 3 mm in depth) were prepared on the buccal surface of 144 bovine incisors. The composite resins were bulk-inserted and polymerized using different light-curing units and times: conventional QTH (quartz-tungsten-halogen; 700 mW/cm²; 20 s, 30 s and 40 s); LED (light-emitting diode; 440 mW/cm²; 20 s, 30 s and 40 s); PAC (xenon plasma arc; 1700 mW/cm²; 3 s, 4.5 s and 6 s). The specimens were stored at 37°C for 24 h prior to sectioning for Knoop hardness assessment. Three measurements were obtained for each depth: top surface, 1 mm and 2 mm. Data were analyzed statistically by ANOVA and Tukey's test (p<0.05). Regardless of the light source or energy density, Knoop hardness of Z250 was statistically significant higher than that of Esthet-X (p<0.05). Specimens cured with PAC had lower hardness than those cured with QTH and LED (p<0.05). Higher Knoop hardness was obtained when the energy density was increased for LED and PAC (p<0.05). No statistically significant differences (p>0.05) were found for QTH. Knoop hardness values decreased with the increase of depth. The increase of energy density produced composites with higher Knoop hardness means using LED and PAC.

Effect of Tooth-Whitening Procedures on Stained Composite Resins

2019 ◽  
Vol 44 (1) ◽  
pp. 65-75 ◽  
Author(s):  
JW Reinhardt ◽  
MM Balbierz ◽  
CM Schultz ◽  
B Simetich ◽  
MW Beatty
Keyword(s):  
Red Wine ◽  
Composite Resin ◽  
Color Change ◽  
Composite Resins ◽  
The Other ◽  
Time Interval ◽  
Distilled Water ◽  
Water Control ◽  
Tooth Whitening ◽  
Final Composite

SUMMARY In this laboratory study, a composite resin was stained to a visibly discernible level using both coffee and red wine over 14 days (change was considered clinically noticeable and significant when ΔEab*≥2.7). Color change was measured at one, three, seven, and 14 days of staining. Although the nature of color change was different for the two staining solutions, the overall degree of staining (ΔEab*) rendered by either coffee or wine at each time interval was not significantly different (p≥0.05). Four whitening protocols were applied to stained composites. Treatment included applications of distilled water (control), Crest Pro-Health [HD] toothpaste, Crest Whitestrips, Opalescence PF bleach (15%), and application of a fine pumice polishing (Preppies). HD toothpaste and Whitestrips were applied daily for 21 days, Opalescence was applied daily for 10 days, and polishing was applied once. Each of the whitening products, applied in a manner simulating at-home or in-office treatment, was effective in producing color improvements (lightening) over controls (p&lt;0.05), but none of the four treatments produced lightening that was significantly different from the other treatments (p≥0.05). A comparison of final composite color with that measured at baseline showed that Opalescence returned composite color to an acceptable level following exposure to both staining solutions (ΔEab*&lt;2.7), Whitestrips returned color close to baseline for wine-stained composites, and HD paste and polishing permitted residual stain to remain (ΔEab*≥2.7).

scholarly journals Influence of additional polymerization in the microhardness of direct composite resins

2010 ◽  
Vol 10 (2) ◽  
Author(s):  
Geraldo Henrique L. Lombardo ◽  
Cristiane F. Carvalho ◽  
Graziela Galhano ◽  
Rodrigo Othávio A. Souza ◽  
Lafayete N. Júnior ◽  
...  
Keyword(s):  
Vickers Microhardness ◽  
Resin Composite ◽  
Saint Paul ◽  
Metallic Matrix ◽  
Composite Resins ◽  
The Other ◽  
Distilled Water ◽  
Anova Test ◽  
Tukey Test

Objective: To evaluate different methods of additional polymerization in the Vickers’ microhardness of three composite resins. Material and Methods: With assistance of a metallic matrix (3 x 4mm), 30 specimens (sps) of each direct resin composite (drc) were prepared, entitled: Filtek Z250(3M ESPE, Saint Paul/MN-USA)(Gr1), W3D(Wilcos, Petrópolis/ RJ-Brazil)(Gr2), and EstheticX (Dentsply/York/PA-USA)(Gr3). All sps were photopolimerized, by the incremental technique, during 40 seconds (Gr1 - n=10: control). After that, 20 samples of each group were divided and half of the samples (n=10) were submitted to the additional polymerization during 15 minutes to 127ºC in autoclave (Gr2) and the other half in stove (Gr3). After all sps were stored in distilled water (37ºC/24 hours). The microhardness was accomplished in digital machine (Future-Tech, FM 700 Model), with 50kg of load. The data obtained (Kg/mm2) were analyzed utilizing the ANOVA Test (2 factors) and Tukey test (p<0.05). Results: The values of mean ± standar  deviations obtained were: Gr1a(84,2±5,1), Gr1b (71,6±6,7), Gr1c (89,6±7,4), Gr2a (101,1±6,0), Gr2b (96,4±9,0), Gr2c (112,6±7,3), Gr3a (74,0±6,5), Gr3b (66,0±12,7) e Gr3c (81,7±6,5). The polymerization in stove produced a higher microhardness than the other kinds of polymerization (p<0.05) and the microhardness of the resins statistically differed among them (p<0.05). Conclusion: The additional polymerization of the Filtek Z250 in the stove produced microhardness statistically higher than the others.

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