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Teixeira CDS, Vitali FC, Bortoluzzi EA, Garcia LDFR. Longer light-curing time decreases the effect of ageing on composite resin hardness used in root reinforcement. AUST ENDOD J 2024. [PMID: 38745526 DOI: 10.1111/aej.12856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/16/2024]
Abstract
This study evaluated the hardness of a composite resin used for root reinforcement, considering the light-curing time, root canal region and ageing due to long-term storage. Twenty incisor roots were reinforced using composite resin, varying the photopolymerisation time (40 or 120 s). Following fibre post cementation, the roots were transversely sectioned into coronal, middle and apical regions. Composite hardness was measured initially and after 18 months of water storage. Data underwent repeated measures analysis of variance and Tukey's post hoc tests. The factors 'light-curing time', 'root region' and 'ageing' affected the hardness. Significant interactions were observed between 'light-curing time × root region' and 'ageing × light-curing time'. Regardless of time, resin hardness in the apical region was lower. After ageing, hardness in the coronal and middle regions decreased when the light-curing time was 40 s, while no significant effect on hardness was noted with a light-curing time of 120 s.
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Affiliation(s)
| | - Filipe Colombo Vitali
- Department of Dentistry, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Eduardo Antunes Bortoluzzi
- Department of Diagnosis & Oral Health, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
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Leyva Del Rio D, Johnston WM. Effect of monomer composition and filler fraction on surface microhardness and depth of cure of experimental resin composites. Eur J Oral Sci 2023; 131:e12933. [PMID: 37121780 DOI: 10.1111/eos.12933] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/28/2023] [Indexed: 05/02/2023]
Abstract
This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A-glycidyl methacrylate [Bis-GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol-A dimethacrylate [Bis-EMA], and Fit-852) with triethylene glycol dimethacrylate (TEGDMA) used as a co-monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5 mm up to 4 mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA-based composites, while Bis-GMA-based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis-GMA and Bis-EMA showed significantly lower values than UDMA or Fit-852. Composites having 50 wt% filler showed a significantly higher depth of cure than those with 60 and 70 wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.
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Affiliation(s)
- Diana Leyva Del Rio
- The Ohio State University, College of Dentistry, Division of Restorative and Prosthetic Dentistry, Columbus, Ohio, USA
| | - William Michael Johnston
- The Ohio State University, College of Dentistry, Division of Restorative and Prosthetic Dentistry, Columbus, Ohio, USA
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Pieniak D, Niewczas AM, Pikuła K, Gil L, Krzyzak A, Przystupa K, Kordos P, Kochan O. Effect of Hydrothermal Factors on the Microhardness of Bulk-Fill and Nanohybrid Composites. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2130. [PMID: 36903245 PMCID: PMC10004216 DOI: 10.3390/ma16052130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/27/2023] [Accepted: 03/03/2023] [Indexed: 06/18/2023]
Abstract
This study evaluates the effect of aging in artificial saliva and thermal shocks on the microhardness of the bulk-fill composite compared to the nanohybrid composite. Two commercial composites, Filtek Z550 (3M ESPE) (Z550) and Filtek Bulk-Fill (3M ESPE) (B-F), were tested. The samples were exposed to artificial saliva (AS) for one month (control group). Then, 50% of the samples from each composite were subjected to thermal cycling (temperature range: 5-55 °C, cycle time: 30 s, number of cycles: 10,000) and another 50% were put back into the laboratory incubator for another 25 months of aging in artificial saliva. The samples' microhardness was measured using the Knoop method after each stage of conditioning (after 1 month, after 10,000 thermocycles, after another 25 months of aging). The two composites in the control group differed considerably in hardness (HK = 89 for Z550, HK = 61 for B-F). After thermocycling, the microhardness decrease was for Z550 approximately 22-24% and for B-F approximately 12-15%. Hardness after 26 months of aging decreased for Z550 (approximately 3-5%) and B-F (15-17%). B-F had a significantly lower initial hardness than Z550, but it showed an approximately 10% lower relative reduction in hardness.
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Affiliation(s)
- Daniel Pieniak
- Tribology Center, Łukasiewicz Research Network-Institute for Sustainable Technologies (L-ITEE), Ul. Pułaskiego 6/10, 26-600 Radom, Poland
- Faculty of Transport and Computer Science, WSEI University, Projektowa 4, 20-209 Lublin, Poland
| | - Agata M. Niewczas
- Department of Conservative Dentistry with Endodontics, Medical University of Lublin, W. Chodźki 6, 20-093 Lublin, Poland
| | - Konrad Pikuła
- Department of Conservative Dentistry with Endodontics, Medical University of Lublin, W. Chodźki 6, 20-093 Lublin, Poland
| | - Leszek Gil
- Faculty of Transport and Computer Science, WSEI University, Projektowa 4, 20-209 Lublin, Poland
| | - Aneta Krzyzak
- Faculty of Aeronautics, Military University of Aviation in Dęblin, 35 Dywizjonu 303, 08-521 Deblin, Poland
| | - Krzysztof Przystupa
- Department of Automation, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland
| | - Paweł Kordos
- Institute of Transport, Combustion Engines and Ecology, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland
| | - Orest Kochan
- School of Computer Science, Hubei University of Technology, Wuhan 430068, China
- Department of Measuring Information Technologies, Lviv Polytechnic National University, Bandery Str. 12, 79013 Lviv, Ukraine
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Labrie D, Price RB, Sullivan B, Salazar AM, Gautam D, Stansbury JW, Ferracane JL. Effect of thickness on the degree of conversion of two bulk-fill and one conventional posterior resin-based composites at high irradiance and high temporal resolution. J Mech Behav Biomed Mater 2022; 136:105489. [PMID: 36206689 DOI: 10.1016/j.jmbbm.2022.105489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVES This study: 1) measures the effect of sample thickness and high irradiance on the depth-dependent time delay before photopolymerization reaction onset; 2) determines if exposure reciprocity exists; 3) measures the conversion rate at four irradiance levels; 4) determines the time, t0, at which the maximum DC rate is reached for two bulk-fill and one conventional posterior resin-based composites (RBCs). METHODS Tetric PowerFill IVA shade (Ivoclar Vivadent) and Aura bulk-fill ultra universal restorative (SDI), and one conventional posterior resin-based composite (RBC), Heliomolar A3 (Ivoclar Vivadent), that were either 0.2 mm, 2 mm, or 4 mm thick were photocured using a modified Bluephase G4 (Ivoclar Vivadent) light-curing unit (LCU) that delivered a single emission band (wavelength centered at 449 nm). The same radiant exposure of 24 J/cm2 was delivered at irradiances ranging from 0.5 to 3 W/cm2 by adjusting the exposure time. PowerFill was also photocured for 3 s or 6 s using a Bluephase PowerCure LCU (Ivoclar Vivadent) on the 3 s mode setting. The degree of conversion (DC) was measured in real-time at a high temporal resolution at 30 °C using Attenuated Total Reflection (ATR) FTIR spectroscopy with a sampling rate of 13 DC data points per second. The DC data were analyzed using a phenomenological autocatalytic model. The RBC viscosity was measured at 21 °C and 30 °C. Light transmission through the RBC samples at 22 °C was monitored with time to calculate the extinction coefficients of the RBCs. RESULTS The time delay before photopolymerization started increased as the RBC thickness increased and the irradiance decreased. An autocatalytic model described the DC data. The time t0 was less than 77 ms for the 0.2 mm thick samples of PowerFill irradiated using the highest irradiance of 3 W/cm2. Among the three RBCs for each sample thickness and irradiance level, the PowerFill had the smallest time t0. There was a time delay of 0.59 s and 1.25 s before the DC started to increase at the bottom of 4 mm thick samples for the PowerFill and Aura, respectively, when an irradiance of 1 W/cm2 was delivered. The time delay increased to 3.65 s for the Aura when an irradiance of 0.5 W/cm2 was delivered. The extinction coefficients near 449 nm were 0.78 mm-1, 0.76 mm-1, and 1.55 mm-1 during the first 2 s after the start of photocuring of PowerFill, Aura, and Heliomolar, respectively. Only PowerFill followed exposure reciprocity. At T = 30 °C, the viscosity was 3400, 17000, and 5200 Paˑs for PowerFill, Aura, and Heliomolar, respectively. SIGNIFICANCE The time delay between when photopolymerization starts at the top and bottom of 2- or 4-mm thick RBC restorations may affect the structural integrity of the bond between the tooth and the bottom of the restoration. Only PowerFill followed exposure reciprocity between irradiance levels of 0.5 to 3 W/cm2. Exposure reciprocity did not occur for Aura or Heliomolar, neither of which are optimized for short light exposure or high irradiance conditions.
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Affiliation(s)
- Daniel Labrie
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
| | - Richard B Price
- Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Braden Sullivan
- Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Austyn M Salazar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80309-0596, United States
| | - Dixa Gautam
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80309-0596, United States
| | - Jeffrey W Stansbury
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80309-0596, United States; Department of Craniofacial Biology, School of Dental Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, 80045, United States
| | - Jack L Ferracane
- Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR, United States
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Grazioli G, Cuevas-Suarez CE, Mederos M, DE Leon E, Garcia A, Zamarripa-Calderón E, Piva E. Evaluation of irradiance and radiant exposure on the polymerization and mechanical properties of a resin composite. Braz Oral Res 2022; 36:e082. [PMID: 35703707 DOI: 10.1590/1807-3107bor-2022.vol36.0082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 03/07/2022] [Indexed: 11/21/2022] Open
Abstract
The objective of the present study was to evaluate the effect of irradiance and radiant exposure on the chemical-mechanical properties of a resin composite. A micro-hybrid resin composite (Clearfil AP-X, Kuraray) was investigated under two different irradiances: low (300 mW/cm2) and high (800 mW/cm2) and radiant exposures: 8 and 16 J/cm2. Four groups, named Low 8 J/cm2, High 8 J/cm2, Low 16 J/cm2, and High 16 J/cm2 were tested, and their flexural strengths, elastic moduli, depths of cure, and degrees of conversion were evaluated. Data were analyzed using two-way ANOVA and Tukey's test. A multiple linear regression model was used to correlate the irradiance and radiant exposure with dependent variables (α = 0.05). Irradiance and radiant exposure were found statistically significant for all dependent variables. The interaction between the factors was statistically significant only for the degree of conversion and elastic modulus. Group Low 16 J/cm2 exhibited a significantly superior performance in all the evaluated properties. Barring the degree of conversion, no significant differences were observed among the properties evaluated between the Low 8 J/cm2 and High 8 J/cm2 groups. The adjusted R2 values were high for the depth of cure and degree of conversion (0.58 and 0.96, respectively). Both irradiance and radiant exposure parameters play an important role in establishing the final properties of a micro-hybrid resin composite. Irradiance has a greater influence under higher radiant exposures.
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Affiliation(s)
- Guillermo Grazioli
- Universidad de la República , School of Dentistry , Department of Dental Materials , Montevideo , Uruguay
| | - Carlos Enrique Cuevas-Suarez
- Autonomous University of Hidalgo State , Academic Area of Dentistry , Dental Materials Laboratory , San Agustín Tlaxiaca , Hgo , Mexico
| | - Matías Mederos
- Universidad de la República , School of Dentistry , Department of Dental Materials , Montevideo , Uruguay
| | - Elisa DE Leon
- Universidad de la República , School of Dentistry , Department of Dental Materials , Montevideo , Uruguay
| | - Andrés Garcia
- Universidad de la República , School of Dentistry , Department of Dental Materials , Montevideo , Uruguay
| | - Eliezer Zamarripa-Calderón
- Autonomous University of Hidalgo State , Academic Area of Dentistry , Dental Materials Laboratory , San Agustín Tlaxiaca , Hgo , Mexico
| | - Evandro Piva
- Universidade Federal de Pelotas - UFPel, School of Dentistry , Department of Restorative Dentistry , Pelotas , RS , Brazil
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Garrofé AB, Picca M, Kaplan AE. Determination of microhardness of bulk-fill resins at different depths. ACTA ODONTOLOGICA LATINOAMERICANA : AOL 2022; 35:10-15. [PMID: 35700536 DOI: 10.54589/aol.35/1/10] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/01/2022] [Indexed: 06/15/2023]
Abstract
The aim of this study was to determine Vickers microhardness (HV) in bulk fill resins at different depths. Test specimens were prepared with different bulk fill resins: Filtek Bulk-Fill (3M ESPE) [FBF], Surefill SDR flow (Dentsply) [SDR], Fill-UP (COLTENE) [FU] and Surefill (Dentsply) [SF]. Semi-cylindrical test specimens were prepared in a mold 6 mm in diameter and 4 mm thick (n=5). A 1000 mW/cm2 light curing unit was applied (Coltolux LED - Coltene) for 20 seconds. HV was determined with three indentations (Vickers Future Tech FM300, 300 g, 8 s) at four depths: 1, 2, 3 and 4 mm from the top surface to the interior. Data were recorded immediately (t0) and 24 hours later (t24). Results were analyzed with two-way ANOVA (p<0.05), and multiple comparisons were performed using Tukey's test. Mean and SD of HV at t0 for each mm were: [FBF] t0: 49.23(4.65) / 48.32(3.36) / 44.38(2.06) / 40.59(2.58); [FBF] t24: 61.37(3.47) / 62.63(3.03) / 57.27(5.22) / 56.37(5.88);[SDR]t0:27.81(3.13) / 28.07(2.4) / 27.24(2.94) / 25.71(3.0); [SDR] t24: 35.11(2.16) / 35.17(1.96) / 35.53(1.81) / 33.18(2.08); [FU] t0: 41.43(1.41) / 39.87(0.88) / 38.11(1.81) / 39.09(1.92); [FU] t24: 49.27(1.54) / 48.77(1.77) / 48.65(1.88) / 46.76(4.93); [SF] t0: 71.35(7.09) / 67.39(9.76) / 68.95(6.21) / 64.1(8.35); [SF] t24: 76.06(6.61) / 75.31(9.37) / 75.2(11.57) / 69.81(12.14). ANOVA showed significant effect of material, depth and recording time (p<0.05), and Tukey's test showed that recording sites (depths) differed significantly, giving four homogeneous groups. Under the conditions of this study, it can be concluded that microhardness of bulk-fill resins can be affected by depth and post-curing time.
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Affiliation(s)
- Analía B Garrofé
- Universidad de Buenos Aires, Facultad de Odontología, Cátedra de Materiales Dentales, Buenos Aires, Argentina.
| | - Mariana Picca
- Universidad de Buenos Aires, Facultad de Odontología, Cátedra de Materiales Dentales, Buenos Aires, Argentina
| | - Andrea E Kaplan
- Universidad de Buenos Aires, Facultad de Odontología, Cátedra de Materiales Dentales, Buenos Aires, Argentina
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Kojic DD, El-Mowafy O, Price R, El-Badrawy W. The Ability of Dental Practitioners to Light-Cure Simulated Restorations. Oper Dent 2021; 46:160-172. [PMID: 34111286 DOI: 10.2341/19-147-c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2020] [Indexed: 11/23/2022]
Abstract
CLINICAL RELEVANCE Using a patient simulator, dental professionals were tested to determine their ability to light-polymerize simulated restorations in their dental practice. After receiving specific instructions and training using the simulator, their ability to deliver sufficient light to polymerize restorations was significantly and substantially improved. SUMMARY Objectives: To determine the ability of dental professionals to deliver a radiant exposure of at least six J/cm2 in 10 seconds to simulated restorations.Methods and Materials: The study initially examined 113 light-emitting-diode (LED) light polymerization units (LPUs) used in dental offices to determine if they could deliver at least 6 J/cm2 radiant exposure (RE) in 10s. This assessment was completed by using a laboratory-grade light measuring device (checkMARC, BlueLight Analytics, Halifax, NS, Canada). The participating dental professionals whose LPUs could deliver 6 J/cm2 then used their own LPU to light-cure simulated anterior and posterior restorations in the MARC Patient Simulator (BlueLight Analytics). They then received specific instructions and were retested using the same LPUs. Data were statistically analyzed with a series of one-way analysis of variance (ANOVA), two-way ANOVA, paired-samples t-tests, Fisher post hoc multiple comparison tests, and McNemar tests with a preset alpha of 0.05 (SPSS Inc).Results: Ten (8.8%) LPUs could not deliver the required RE to the checkMARC in 10s and were eliminated from the study. For the anterior restoration, most dental practitioners (87.3%) could deliver at least 6 J/cm2 before instructions. After receiving additional light-curing instructions, only two (1.9%) participants were unable to deliver 6 J/cm2 to the anterior location. At the posterior location, only 55.3% (57) participants could deliver at least 6 J/cm2 before the instructions. After receiving these instructions, an additional 32 participants delivered at least 6 J/cm2. Overall, after receiving instructions on how to use the LPU correctly, the participants improved the amount of RE they delivered to anterior and posterior restorations by 22.5% and 30%, respectively.Conclusion: This study revealed that at the baseline, 44.7% of participating dental professionals failed to deliver 6 J/cm2 in 10s to the posterior simulated restoration when using their own LPU.
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Lien W, Roberts H, Vandewalle K. Hardness Development in Resin Composite Core Materials. J Prosthodont 2021; 31:305-313. [PMID: 34087039 DOI: 10.1111/jopr.13399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2021] [Indexed: 12/01/2022] Open
Abstract
PURPOSE To investigate the hardness characteristics of 13 contemporary resin core materials. MATERIALS AND METHODS Specimens (n = 12) were fabricated using stainless steel molds with top surfaces of dual-cure products photopolymerized while additional groups were allowed to self-cure. Twelve Knoop hardness indentations 500 microns apart were obtained of photopolymerized top and bottom sample surfaces as well as the self-cured sample surface with the mean recorded as the representative sample hardness. Testing was completed at 10 minutes, 1 hour, and 24 hours. In addition, hardness values were compared to that obtained from polished coronal dentin samples. Mean data between groups were analyzed with Kruskal-Wallis/Dunn's, within groups with repeated measures ANOVA/Tukey's. RESULTS Hardness results were material dependent. All but two products demonstrated a 0.8 bottom/top Knoop hardness ratio at 10 minutes. Product's self-cure cure reaction did not attain hardness similarity with any photopolymerized top surfaces and while some materials were found to have similar dentin hardness to resin top surface ratio similarity, only one product had hardness equal to or greater than that of dentin during any time period. CONCLUSIONS Under this study's conditions, hardness development was material dependent and all but two products demonstrated adequate hardness-derived degree of cure assessment at 10 minutes after preparation. Self-cured samples demonstrated hardness increase; however, no self-cured material achieved hardness similarity to photopolymerized top surfaces. None of the materials achieved hardness similarity to dentin and only one product demonstrated hardness greater than that of dentin.
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Affiliation(s)
- Wen Lien
- USAF Dental Research & Consultation Service, JBSA-Fort Sam Houston, San Antonio, Texas
| | - Howard Roberts
- University of Kentucky, College of Dentistry, Lexington, Kentucky.,Uniformed Services University of the Health Sciences, Postgraduate Dental School, Bethesda, Maryland
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Slack WE, Yancey EM, Lien W, Sheridan R, Phoenix R, Vandewalle K. Effect of high-irradiance light curing on exposure times and pulpal temperature of adequately polymerized composite. Dent Mater J 2020; 39:976-983. [PMID: 32727961 DOI: 10.4012/dmj.2019-236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study investigated the effect of high-irradiance light-curing on exposure time and pulpal temperature of adequately-cured composite. Composite placed in a molar preparation was cured using high-irradiance light-curing units (Flashmax P3, Valo, S.P.E.C. 3 LED, Cybird XD) and tested for hardness occlusal-gingivally. The first group had exposure times set according to manufacturer settings (recommended), second group to yield 80% of maximum hardness at the 2 mm depth (experimental), and third group was set at 20 s (extended). Exposure time necessary to adequately polymerize the composite at 2 mm depth was 9 s for the Cybird XD and Valo and 12 s for S.P.E.C. 3 LED and Flashmax P3. None of the high-irradiance light-curing units adequately polymerized the composite at the manufacturer-recommended minimum-exposure times of 1-3 s. Exposure times necessary to adequately polymerize composite at 2 mm resulted in a maximum pulpal-temperature increase well below the temperature associated with possible pulpal necrosis.
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Affiliation(s)
| | | | - Wen Lien
- USAF Dental Research and Consultation Service
| | | | - Rodney Phoenix
- Postgraduate Dental College, Uniformed Services University of the Health Sciences
| | - Kraig Vandewalle
- Advanced Education in General Dentistry Residency.,Uniformed Services University of the Health Sciences
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Guo J, Yang B, Yang J, Holmes B, Fok A, Chen J, Wang Y. Optical and mechanical factors in the temporal development of tooth-composite bond. Dent Mater 2020; 36:660-671. [PMID: 32278482 DOI: 10.1016/j.dental.2020.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/23/2020] [Accepted: 03/12/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVES To obtain an accurate picture of the temporal development of bond strength between resin composites and tooth structures during cure for assessing debonding at the tooth-composite interface. METHODS An assembly of uncured composite sandwiched between a glass block and a dentin slab with a layer of pre-cured adhesive was used in this study. A conventional composite was compared against a bulk-fill composite. The rate of bond formation was determined by measuring the tensile bond strength of specimens of different thicknesses at different time points during cure. The changing light irradiance exiting the composite as it cured was also recorded. Mode of fracture was analyzed by examining the fracture surfaces. RESULTS Photo-bleaching occurred in both resin composites. The development of the dentin-composite bond strength was initially dictated by the developing cohesive strength of the resin composite, and its final value was capped by the strength of the preformed dentin-adhesive bond. The higher interfacial irradiance in the bulk-fill composite did not lead to faster development of the overall bond strength. This was caused by its slower rate of cohesive strength development as reflected in the longer time for its interfacial irradiance to plateau and the greater proportion of cohesive failure seen in the initial stage of polymerization. The law of reciprocity did not hold for the development of dentin bond strength. SIGNIFICANCE The results from this study, when compared with the development of shrinkage stress, can be used as a basis for ensuring the integrity of the dentin-composite interface during cure.
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Affiliation(s)
- Jiawen Guo
- Department of Prosthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Bo Yang
- Department of Prosthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Jiajun Yang
- Department of Prosthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Brian Holmes
- Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB), School of Dentistry, University of Minnesota, MN, USA
| | - Alex Fok
- Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB), School of Dentistry, University of Minnesota, MN, USA.
| | - Jihua Chen
- State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
| | - Yan Wang
- Department of Prosthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China.
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Shimokawa C, Turbino ML, Giannini M, Braga RR, Price RB. Effect of Curing Light and Exposure Time on the Polymerization of Bulk-Fill Resin-Based Composites in Molar Teeth. Oper Dent 2020; 45:E141-E155. [PMID: 32053458 DOI: 10.2341/19-126-l] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study examined the influence of different light-curing units (LCUs) and exposure times on the microhardness across bulk-fill resin-based composite (RBC) restorations in a molar tooth. METHODS AND MATERIALS Tip diameter, radiant power, radiant exitance, emission spectra, and light beam profile were measured on two single-emission-peak LCUs (Celalux 3 and DeepCure-S) and two multiple-peak LCUs (Bluephase 20i and Valo Grand). A mold was made using a human molar that had a 12-mm mesial-distal length, a 2.5-mm deep occlusal box, and two 4.5-mm deep proximal boxes. Two bulk-fill RBCs (Filtek Bulk Fill Posterior and Tetric EvoCeram Bulk Fill) were photoactivated for 10 seconds and for 20 seconds, with the light guide positioned at the center of the occlusal surface. Microhardness was then measured across the transverse surface of the restorations. The light that reached the bottom of the proximal boxes was examined. Data were statistically analyzed with the Student t-test, two-way analysis of variance, and the Tukey post hoc test (α=0.05). RESULTS The four LCUs were different regarding all the tested characteristics. Even when using LCUs with wide tips and a homogeneous beam profile, there were significant differences in the microhardness results obtained at the central and proximal regions of the RBCs (p<0.05). LCUs with wider tips used for 20 seconds produced higher microhardness values (p<0.05). The multiple-peak LCUs produced greater hardness values in Tetric EvoCeram Bulk Fill than did the single-emission-peak LCUs (Celalux 3 and DeepCure-S). Results for the light measured at the bottom of proximal boxes showed that little light reached these regions when the light tip was positioned at the center of restorations. CONCLUSIONS Curing lights with wide tips, homogeneous light beam profiles, and longer exposure times are preferred when light-curing large MOD restorations. Light curing from more than one position may be required for adequate photopolymerization.
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Erickson RL, Barkmeier WW. Comparisons of ISO depth of cure for a resin composite in stainless-steel and natural-tooth molds. Eur J Oral Sci 2019; 127:556-563. [PMID: 31553092 DOI: 10.1111/eos.12652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to compare the depth of cure (DOC) of a resin-based composite (RBC) using the ISO DOC protocol with stainless-steel and molar-tooth molds (4 mm cylindrical cavity). The tooth mold included testing with and without the occlusal surface being covered with black tape around the cavity opening. The RBC was cured with either halogen (HAL) or light-emitting diode (LED) light. The results showed that specimens made in the non-taped tooth mold had DOCs that were significantly greater (28%-35%) than those in the stainless-steel mold. The taped tooth mold also produced significantly greater DOCs, but only by 6%-8%. Knoop hardness (KNH) measurements along the central axis of the RBC specimens showed that depths for 80% of maximum hardness were substantially greater than those determined by the ISO DOC protocol but were limited to the center and quickly dropped below 80% in a lateral direction. The KHN mapping for each of the three molds found that the ISO DOCs could validate a KHN of ≥80% across the RBC to the periphery, only for the non-taped tooth mold. This was due to light incident on the tooth surrounding the RBC being scattered into the RBC.
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Affiliation(s)
- Robert L Erickson
- Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE, USA
| | - Wayne W Barkmeier
- Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE, USA
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13
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Efficacy of light-emitting diode light polymerization units used in private practices in Toronto, Ontario, Canada. J Am Dent Assoc 2019; 150:802-808. [DOI: 10.1016/j.adaj.2019.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 06/02/2019] [Accepted: 06/04/2019] [Indexed: 11/22/2022]
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14
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Tanthanuch S, Kukiattrakoon B. The effect of curing time by conventional quartz tungsten halogens and new light-emitting diodes light curing units on degree of conversion and microhardness of a nanohybrid resin composite. J Conserv Dent 2019; 22:196-200. [PMID: 31142993 PMCID: PMC6519180 DOI: 10.4103/jcd.jcd_498_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Background: Little is known about the relationship between the minimal light-curing time required for proper polymerization on various quartz–tungsten–halogen (QTH) and light-emitting diode (LED) light-curing units that have different light intensities. Aim: To evaluate the effects of curing time by QTH and LED light-curing units on the degree of conversion (DoC) and surface microhardness of a nanohybrid resin composite. Setting and Design: Experimental design. Materials and Methods: One hundred and twenty cylindrical specimens (4.0 mm in diameter, 2.0 mm thick) of shade A2 resin composite were prepared and polymerized with either QTHs or LEDs for 20 and 40 s. The DoC and the top and bottom surface microhardness were recorded. Statistical Analysis Used: Two-way analysis of variance, Tukey's test, and the t-test (α = 0.05) were used. Results: Surface microhardness and DoC values were affected by light intensity and curing time (P < 0.05). In terms of microhardness and DoC, LED groups gave significantly more values than QTH groups (P < 0.05). Conclusion: Curing time affected surface microhardness and DoC values of a nanohybrid resin composite in both conventional QTH and new LED light-curing units.
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Affiliation(s)
- Saijai Tanthanuch
- Department of Conservative Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand
| | - Boonlert Kukiattrakoon
- Department of Conservative Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.,Dental Materials Research Unit (Second Phase), Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand
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15
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Cuevas-Suárez CE, Meereis CTW, D'accorso N, Macchi R, Ancona-Meza AL, Zamarripa-Calderón E. Effect of radiant exposure and UV accelerated aging on physico-chemical and mechanical properties of composite resins. J Appl Oral Sci 2019; 27:e20180075. [PMID: 30624462 PMCID: PMC6322643 DOI: 10.1590/1678-7757-2018-0075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 09/09/2018] [Indexed: 12/04/2022] Open
Abstract
Currently, there is no consensus in terms of defining the minimum radiant exposure values necessary for achieving adequate properties of composite resin. In addition, the long-term influence that radiant exposure has on the properties of composite resins is still questionable. Objective: The objective of this study was to evaluate the effect of radiant exposure and UV accelerated aging on the physico-chemical and mechanical properties of micro-hybrid and nanofilled composite resins. Material and Methods: A nanofilled (Filtek Supreme; 3M ESPE) and a micro-hybrid composite resin (Filtek Z250; 3M ESPE) were investigated under different radiant exposures (3.75, 9, and 24 J/cm2) and UV accelerated aging protocols (0, 500, 1000, and 1500 aging hours). The degree of conversion (DC), flexural strength (FS), modulus (M), water sorption (WS), and solubility (WL) were evaluated. The results obtained were analyzed using two-way ANOVA and Tukey's test. Comparisons were performed using a significance level of α=0.05. Results: The DC, FS, and M were found to be significantly influenced by both radiant exposure and accelerated aging time. The DC and EM increased with radiant exposure in the no-aging group (0-hour aging) for both micro-hybrid and nanofilled composites, whereas no correlation was found after accelerated aging protocols. WS and WL of micro-hybrid and nanofilled composite resins were scarcely affected by radiant exposure (p>0.05), whereas they were significantly reduced by accelerated aging (p<0.001). Conclusions: Although increasing radiant exposure affected the degree of conversion and mechanical properties of micro-hybrid and nanofilled composites, no influence on the hydrolytic degradation of the material was observed. In contrast, UV accelerated aging affected both the physico-chemical and mechanical properties of the composites.
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Affiliation(s)
- Carlos Enrique Cuevas-Suárez
- Universidad Autónoma del Estado de Hidalgo, Instituto de Ciencias de la Salud, Área Académica de Odontología, Pachuca de Soto, México
| | - Carine Tais Walter Meereis
- Universidade Federal dos Vales do Jequitinhonha e Mucuri, Programa de Pós-Graduação em Odontologia, Diamantina, Minas Gerais, Brasil
| | - Norma D'accorso
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina
| | - Ricardo Macchi
- Universidad de Buenos Aires, Facultad de Odontología, Departamento de Materiales Dentales, Buenos Aires, Argentina
| | - Adriana Leticia Ancona-Meza
- Universidad Autónoma del Estado de Hidalgo, Instituto de Ciencias de la Salud, Área Académica de Odontología, Pachuca de Soto, México
| | - Eliezer Zamarripa-Calderón
- Universidad Autónoma del Estado de Hidalgo, Instituto de Ciencias de la Salud, Área Académica de Odontología, Pachuca de Soto, México
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Besegato JF, Jussiani EI, Andrello AC, Fernandes RV, Salomão FM, Vicentin BLS, Dezan-Garbelini CC, Hoeppner MG. Effect of light-curing protocols on the mechanical behavior of bulk-fill resin composites. J Mech Behav Biomed Mater 2018; 90:381-387. [PMID: 30419538 DOI: 10.1016/j.jmbbm.2018.10.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the effect of two light-curing protocols on mechanical behavior of three bulk-fill resin composites (BFRC) considering their optical properties. METHODS One increment of 4 mm thickness of the bulk-fill resin composites Opus Bulk Fill, Tetric N-Ceram and Filtek Bulk Fill Flow were submitted to two different light-curing protocols: Sp - irradiance of 1000 mW/cm2 (20 s); Xp - irradiance of 3200 mW/cm2 (6 s). To assess the influence on the mechanical behavior it was studied polymerization shrinkage by X-ray microtomography (n = 3), Vickers hardness (n = 10) at the top and bottom surfaces of the samples, irradiance reaching the bottom surface (n = 3) and absorbance spectrum during the light-curing time interval (n = 3). Data were analyzed by two-way ANOVA test for parametric data and Kruskal Wallis test, followed by Wilcoxon or Mann-Whitney U post-test, for non-parametric data. RESULTS All BFRCs contracted when light-cured, with greater contraction for Xp. Filltek Bulk Fill Flow showed highest polymerization shrinkage, for both Sp and Xp. All BFRCs showed minor hardness values on the bottom surface, with greater reduction for Xp. All BFRCs exhibited a decrease in irradiance at 4 mm depth. A decrease in absorbance intensity throughout the light-cure was observed, except for Opus Bulk Fill. CONCLUSIONS Regardless BFRCs composition, the light-curing protocol with lower irradiance and longer exposure time results in lower polymerization shrinkage and higher hardness. The higher irradiance in a shorter time interval compromises the mechanical behavior of the resin composites, which may result in undesirable clinical outcomes.
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Affiliation(s)
- João Felipe Besegato
- Department of Restorative Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil.
| | - Eduardo Inocente Jussiani
- Department of Physics, State University of Londrina - UEL, Rodovia Celso Garcia Cid, Pr 445 Km 380, 86057-970 Londrina, PR, Brazil
| | - Avacir Casanova Andrello
- Department of Physics, State University of Londrina - UEL, Rodovia Celso Garcia Cid, Pr 445 Km 380, 86057-970 Londrina, PR, Brazil
| | - Ricardo Vignoto Fernandes
- Department of Physics, State University of Londrina - UEL, Rodovia Celso Garcia Cid, Pr 445 Km 380, 86057-970 Londrina, PR, Brazil
| | - Fabio Martins Salomão
- Department of Restorative Dentistry, Araçatuba Dental School, São Paulo State University - UNESP, Rua José Bonifácio 1193, 16015-050 Araçatuba, SP, Brazil
| | - Bruno Luiz Santana Vicentin
- Department of Physics, State University of Londrina - UEL, Rodovia Celso Garcia Cid, Pr 445 Km 380, 86057-970 Londrina, PR, Brazil
| | - Cássia Cilene Dezan-Garbelini
- Department of Oral Medicine and Pediatric Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil
| | - Márcio Grama Hoeppner
- Department of Restorative Dentistry, State University of Londrina - UEL, Rua Pernambuco 540, 86020-120 Londrina, PR, Brazil
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Ferracane J, Hilton T, Stansbury J, Watts D, Silikas N, Ilie N, Heintze S, Cadenaro M, Hickel R. Academy of Dental Materials guidance—Resin composites: Part II—Technique sensitivity (handling, polymerization, dimensional changes). Dent Mater 2017; 33:1171-1191. [DOI: 10.1016/j.dental.2017.08.188] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 08/29/2017] [Indexed: 11/30/2022]
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AlShaafi MM. Effects of delivering the same radiant exposures at 730, 1450, and 2920 mW/cm 2 to two resin-based composites. Eur J Dent 2017; 11:22-28. [PMID: 28435361 PMCID: PMC5379830 DOI: 10.4103/ejd.ejd_270_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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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Affiliation(s)
- Maan M AlShaafi
- Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
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19
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Erickson RL, Barkmeier WW. Effect of mold diameter on the depth of cure of a resin-based composite material. Eur J Oral Sci 2017; 125:88-92. [PMID: 28066997 DOI: 10.1111/eos.12325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Robert L. Erickson
- Department of General Dentistry; Creighton University School of Dentistry; Omaha NE USA
| | - Wayne W. Barkmeier
- Department of General Dentistry; Creighton University School of Dentistry; Omaha NE USA
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20
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Effect of layer thickness on the elution of bulk-fill composite components. Dent Mater 2017; 33:54-62. [DOI: 10.1016/j.dental.2016.10.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 09/30/2016] [Accepted: 10/24/2016] [Indexed: 12/21/2022]
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21
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Effect of curing light emission spectrum on the nanohardness and elastic modulus of two bulk-fill resin composites. Dent Mater 2016; 32:535-50. [DOI: 10.1016/j.dental.2015.12.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 12/21/2015] [Accepted: 12/21/2015] [Indexed: 02/01/2023]
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22
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AlShaafi MM. Effects of Different Temperatures and Storage Time on the Degree of Conversion and Microhardness of Resin-based Composites. J Contemp Dent Pract 2016; 17:217-23. [PMID: 27207201 DOI: 10.5005/jp-journals-10024-1830] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Dental materials are often made at room temperature, whereas clinically they are made in the mouth. This study evaluated the effects of temperature on the degree of conversion (DC) and Knoop microhardness (KHN). MATERIALS AND METHODS Two types of resin-based composites (RBCs) were light-cured using a light-emitting diode (LED) light-curing unit. The resin specimens were centered on an Attenuated Total Reflectance Fourier transform infrared (FT-IR) plate heated to 23°C or 33°C. The DC of the resin was calculated after 120 seconds, the specimens were removed, and the KHN was tested at the bottom of the specimens both immediately, after 24 hours, and after 7 days storage in distilled water in complete darkness at 37°C. The effects of different temperatures on the DC and KHN with their storage time were compared by analysis of variance and Fisher's protected least significant difference post hoc multiple comparison tests (p < 0.05). RESULTS Increasing the temperature had a significant and positive effect on the DC and KHN for immediate values of the RBCs. Greater conversion and hardness occurred when the curing temperature was increased from 23°C to 33°C. The KHN increased significantly after 24 hours of storage. There was a linear relationship between DC and KHN (R(2) = 0.86) within the range of DC and KHN studied. CONCLUSION The physical properties of dental materials can be expected to be better when made in the mouth than when they are made in a laboratory at room temperature.
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Affiliation(s)
- Maan M AlShaafi
- Associate Professor, Department of Restorative Dental Sciences, College of Dentistry King Saud University, Riyadh, Kingdom of Saudi Arabia, Phone: +966114677420, e-mail:
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23
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ALShaafi MM, Haenel T, Sullivan B, Labrie D, Alqahtani MQ, Price RB. Effect of a broad-spectrum LED curing light on the Knoop microhardness of four posterior resin based composites at 2, 4 and 6-mm depths. J Dent 2015; 45:14-8. [PMID: 26593741 DOI: 10.1016/j.jdent.2015.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/16/2015] [Accepted: 11/18/2015] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco). METHODS The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition. RESULTS As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA p<0.05). Although the KHN of SureFil SDR Flow was only marginally significantly different between the 2 and 6-mm thickness, the bottom at 6-mm was only 59% of the hardness measured at the top. CLINICAL SIGNIFICANCE This study highlights that clinicians need to consider how the depth of cure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin.
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Affiliation(s)
- Maan M ALShaafi
- King Saud University, Restorative Dental Sciences, P.O. Box 60169, Riyadh 11545, Saudi Arabia
| | - Thomas Haenel
- Dental Clinical Sciences, Dalhousie University, P.O. Box 15000, Halifax, NS B3H4R2, Canada; University of Bonn-Rhein-Sieg, Applied Sciences, Department of Natural Sciences, von-Liebig-Strasse 20, 53359 Rhinebach, Germany; Tomas Bata University in Zlín, Faculty of Technology, náměstí T. G. Masaryka 275, 76272 Zlín, Czech Republic
| | - Braden Sullivan
- Dental Clinical Sciences, Dalhousie University, P.O. Box 15000, Halifax, NS B3H4R2, Canada
| | - Daniel Labrie
- Department of Physics and Atmospheric Science, Dalhousie University, P.O. BOX 15000, Halifax, NS B3H 4R2, Canada
| | - Mohammed Q Alqahtani
- King Saud University, Restorative Dental Sciences, P.O. Box 60169, Riyadh 11545, Saudi Arabia
| | - Richard B Price
- Dental Clinical Sciences, Dalhousie University, P.O. Box 15000, Halifax, NS B3H4R2, Canada.
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AlQahtani MQ, Michaud PL, Sullivan B, Labrie D, AlShaafi MM, Price RB. Effect of High Irradiance on Depth of Cure of a Conventional and a Bulk Fill Resin-based Composite. Oper Dent 2015; 40:662-72. [PMID: 26237638 DOI: 10.2341/14-244-l] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study evaluated the effect of using three commercial light curing units (LCUs) delivering a range of irradiance values, but delivering similar radiant exposures on the depth of cure of two different resin-based composites (RBCs). METHODS A conventional hybrid RBC (Z100 shade A2, 3M ESPE) or a bulk fill RBC (Tetric EvoCeram Bulk Fill shade IVA, Ivoclar Vivadent) was packed into a 10-mm deep semicircular metal mold with a 2-mm internal radius. The RBC was exposed to light from a plasma-arc-curing (PAC) light (Sapphire Plus, DenMat) for five seconds, a quartz-tungsten-halogen (QTH) light (Optilux 501, Kerr) for 40 seconds, or a light-emitting-diode (LED) light (S10, 3M ESPE) for 20 seconds and 40 seconds (control). The Knoop microhardness was then measured as soon as possible at the top surface and at three points every 0.5 mm down from the surface. For each RBC, a repeated measures analysis of variance (ANOVA) model was used to predict the Knoop hardness in a manner analogous to a standard regression model. This predicted value was used to determine at what depth the RBC reached 80% of the mean hardness achieved at the top surface with any light. RESULTS The PAC light delivered an irradiance and radiant exposure of 7328 mW/cm(2) and 36.6 J/cm(2), respectively, to the RBCs; the QTH light delivered 936 mW/cm(2) and 37.4 J/cm(2) and in 20 seconds the LED light delivered 1825 mW/cm(2) and 36.5 J/cm(2). In 40 seconds, the control LED light delivered a radiant exposure of 73.0 J/cm(2). For Z100, using 80% of the maximum hardness at the top surface as the criteria for adequate curing, all light exposure conditions achieved the 2.0-mm depth of cure claimed by the manufacturer. The LED light used for 40 seconds achieved the greatest depth of cure (5.0 mm), and the PAC light used for five seconds, the least (2.5 mm). Tetric EvoCeram Bulk Fill achieved a 3.5-mm depth of cure when the broad-spectrum QTH light was used for 40 seconds delivering 37.4 J/cm(2). It required a 40-second exposure time with the narrow-spectrum LED, delivering approximately 73 J/cm(2) to reach a depth of cure of 4 mm. CONCLUSIONS When delivering a similar radiant exposure of 37 J/cm(2), the QTH (40 seconds) and LED (20 seconds) units achieved a greater depth of cure than the PAC (five seconds) light. For both resins, the greatest depth of cure was achieved when the LED light was used for 40 seconds delivering 73 J/cm(2) (p<0.05).
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Sword RJ, Do UN, Chang JH, Rueggeberg FA. Effect of Curing Light Barriers and Light Types on Radiant Exposure and Composite Conversion. J ESTHET RESTOR DENT 2015; 28:29-42. [PMID: 26177387 DOI: 10.1111/jerd.12173] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE Previous research investigated the effects of curing tip barriers on light output and composite properties, but no study has measured the effect of a wide variety of barriers and curing light types on delivered radiant exposure and the resulting composite cure 2 mm below the radiated surface. MATERIALS AND METHODS Six barrier materials and six curing light types were tested. Spectroradiometry was used to measure irradiance with and without barriers for each light type, and radiant exposure values were determined for a commercial camphorquinone-based dental composite material. Composite monomer conversion was measured at 10 minutes following exposure for each light type/barrier condition (N = 5) using infrared spectroscopy. Results were subjected to one-way analyses of variance for radiant exposure and conversion among barrier types within a given curing light: preset alpha 0.05. RESULTS All barriers significantly reduced radiant exposure compared with the uncovered tip, but the use of the two polywave LEDs covered with a latex-based barrier demonstrated significantly lower conversion values. CONCLUSIONS Although light-curing barriers reduce radiant exposure to a restorative material over a recommended exposure, this reduction is not sufficient to cause significant reduction in composite cure, except when using a latex-based barrier and a polywave LED curing light. CLINICAL SIGNIFICANCE Clinicians need to be aware of the possible interaction between curing light barriers and curing light type in order to optimally photocure restorative materials.
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Affiliation(s)
- Rhoda Joyner Sword
- Department of Oral Rehabilitation, Georgia Regents University, Augusta, GA, USA
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Dionysopoulos D, Papadopoulos C, Koliniotou-Koumpia E. Effect of temperature, curing time, and filler composition on surface microhardness of composite resins. J Conserv Dent 2015; 18:114-8. [PMID: 25829688 PMCID: PMC4379649 DOI: 10.4103/0972-0707.153071] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 12/24/2014] [Accepted: 01/04/2015] [Indexed: 12/02/2022] Open
Abstract
Aim: The aim of this study was to evaluate the microhardness of two composite resins when subjected to three different temperatures and three different light-curing times. Materials and Methods: Two composites were used; Filtek Z250 and Grandio. Three different temperatures (23, 37, and 55oC) were used, utilizing a composite warmer. The heated samples were immediately injected into cylindrical molds (6 mm × 2 mm) and the top surface of the specimens was polymerized for 10, 20, and 40 sec, using a Quartz-Tungsten-Halogen light-curing unit (QTH LCU). Vickers microhardness measurements were performed from both the top and bottom surface of the specimens, following dry storage for 24 hours in the dark. Statistical analysis were performed using one-way analysis of variance (ANOVA) and Tukey post-hoc test at a level of significance of a = 0.05. Results: The results indicated that there was an increase in microhardness as the temperature of the composite was increased for either the top or the bottom surface (P < 0.05). Furthermore, there was a general increase in microhardness for both composites as curing time increased (P < 0.05). The type of composites did not influence the surface microhardness (P > 0.05). Conclusions: Temperature of composites affects their surface microhardness. Also, light-curing time influence microhardness values of the composites tested.
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Affiliation(s)
- Dimitrios Dionysopoulos
- Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Constantinos Papadopoulos
- Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Eugenia Koliniotou-Koumpia
- Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Curing characteristics of a composite. part 2: the effect of curing configuration on depth and distribution of cure. Dent Mater 2014; 30:e134-45. [PMID: 24656631 DOI: 10.1016/j.dental.2014.02.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 11/20/2013] [Accepted: 02/13/2014] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The objective of this study was to examine the effect different configurations of curing would have on the depth and distribution of the cure within each configuration, for a specific resin-based composite (RBC). METHODS RBC was cured in a variety of configurations, consisting of 6mm molds of three different colors; large molds that simulated the condition of no mold at all; and 3-6mm diameter molds to check the effect of size. All specimens were cured for 20s with a quartz-halogen lamp and were allowed to cure for 24h in the dark. Transmission measurements were made for these same configurations. Knoop hardness measurements were made across the central plane of some configurations to determine the distribution of curing. RESULTS Depths of cure and distribution of curing were significantly affected by changes in configuration. Under the configuration of no mold, the cure extended well beyond the periphery of the light guide due to scattering of the light. When a mold was used, a pronounced effect by the walls resulted in decreased hardness as the mold wall was approached, and the severity of this effect was dependent on the color of the mold. It is believed that this is due to absorption/reflection characteristics of light by the walls, with the white molds showing the least effect. Reducing the diameter of the molds resulted in significant decreases in depth of cure, which are attributed to light absorption by the walls that limits the penetration of light during the curing procedure. SIGNIFICANCE Configuration of curing has a significant effect on the depth of cure, but also significantly reduces the cure near the mold wall. This can have clinical ramifications for the cure along a stainless steel matrix band for Class II restorations, and for test procedures in general, where there is no standardization regarding configuration or where measurements are made on specimens.
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