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De Santis R, Gloria A, Maietta S, Martorelli M, De Luca A, Spagnuolo G, Riccitiello F, Rengo S. Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser. MATERIALS 2018; 11:ma11040504. [PMID: 29584683 PMCID: PMC5951350 DOI: 10.3390/ma11040504] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 03/16/2018] [Accepted: 03/23/2018] [Indexed: 11/16/2022]
Abstract
Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED) curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design)/CAM (computer-aided manufacturing) assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance.
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Affiliation(s)
- Roberto De Santis
- Institute of Polymers, Composites and Biomaterials-National Research Council of Italy, V.le J.F. Kennedy 54-Mostra d'Oltremare Pad. 20, 80125 Naples, Italy.
| | - Antonio Gloria
- Institute of Polymers, Composites and Biomaterials-National Research Council of Italy, V.le J.F. Kennedy 54-Mostra d'Oltremare Pad. 20, 80125 Naples, Italy.
| | - Saverio Maietta
- Department of Industrial Engineering, Fraunhofer JL IDEAS-University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy.
| | - Massimo Martorelli
- Department of Industrial Engineering, Fraunhofer JL IDEAS-University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy.
| | - Alessandro De Luca
- Department of Industrial and Information Engineering, University of Campania "Luigi Vanvitelli", via Roma 29, 81031 Aversa, Italy.
| | - Gianrico Spagnuolo
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Via Pansini, 5, 80125 Naples, Italy.
| | - Francesco Riccitiello
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Via Pansini, 5, 80125 Naples, Italy.
| | - Sandro Rengo
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples Federico II, Via Pansini, 5, 80125 Naples, Italy.
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Conte G, Panetta M, Mancini M, Fabianelli A, Brotzu A, Sorge R, Cianconi L. Curing effectiveness of single-peak and multi-peak led light curing units on tpo-containing resin composites with different chromatic characteristics. ACTA ACUST UNITED AC 2017; 10:140-150. [PMID: 29876039 DOI: 10.11138/orl/2017.10.2.140] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study evaluated the surface microhardness of Lucirin-TPO (TPO) containing resin based composite (RBC) cured with three light-emitting diode (LED) light curing units (LCUs) (two single-peak LED and one multi-peak LED), and two different energy density (ED) (8 J/cm2 and 16 J/cm2). Ninety specimens (8 mm wide and 2 mm thick) (n=5), were prepared with three different shades: translucent (T), A2 dentin (A2d), and A4 dentin (A4d). Specimens were subjected to micro-hardness Vickers measurements (Vickers Hardness Number, VHN) on both top and bottom surfaces. Hardness ratio (rHV) was also calculated. Data were analyzed using multifactorial ANOVA and Bonferroni tests (<=0.05). Results indicated that higher ED performed better than lower ED. Multi-peak LED achieved higher VHNs and rHV than single-peak LED when curing a TPO-containing RBC. A4d invariably achieved lower rHV and VHN than T and A2d. Single-peak LED achieved comparable VHNs and rHVs with multi-peak LED only curing A2d and T shades with 16J/cm2.
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Affiliation(s)
- G Conte
- Department of Restorative Dentistry, Endodontics and Biomaterials, University of Rome "Tor Vergata", Rome, Italy
| | - M Panetta
- Department of Restorative Dentistry, Endodontics and Biomaterials, University of Rome "Tor Vergata", Rome, Italy
| | - M Mancini
- Department of Restorative Dentistry, Endodontics and Biomaterials, University of Rome "Tor Vergata", Rome, Italy
| | - A Fabianelli
- Visiting lecturer in Sheffield University, Sheffield, UK
| | - A Brotzu
- Department of ICMA, "Sapienza" University of Rome, Rome, Italy
| | - R Sorge
- Department of Human Physiology, Laboratory of Biometry, University of Rome "Tor Vergata", Rome, Italy
| | - L Cianconi
- Department of Restorative Dentistry, Endodontics and Biomaterials, University of Rome "Tor Vergata", Rome, Italy
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Abstract
BACKGROUND The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation. METHODS The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer. RESULTS Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization. CONCLUSIONS The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth. PRACTICAL IMPLICATIONS OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.
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Sunada N, Ishii R, Shiratsuchi K, Shimizu Y, Tsubota K, Kurokawa H, Miyazaki M. Ultrasonic measurement of the effects of adhesive application and power density on the polymerization behavior of core build-up resins. Acta Odontol Scand 2013; 71:137-43. [PMID: 22519690 DOI: 10.3109/00016357.2011.654252] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To use ultrasonic measurements to monitor the effects of adhesive application and power density on the polymerization behavior of dual-cured core build-up resins. METHODS Ultrasonic measurements were carried out using a pulser-receiver, transducers and an oscilloscope. The core build-up resins were mixed, inserted into a transparent mold and then placed onto a sample stage with or without self-etch adhesive. Power densities of 0 (no light irradiation), 200 and 600 mW/cm(2) were used for curing. The transit time through the core build-up resin disk was divided by the specimen thickness to obtain the longitudinal sound velocity (V). RESULTS Light irradiation of the core build-up resins at a power density of 600 mW/cm(2) caused V values to rise to an initial plateau of 1550-1650 m/s, then to rise rapidly to a second plateau of 2800-3200 m/s. The rate of V increase was slower when the resin cements were light-irradiated and became faster when irradiated at a higher power density. There were no significant differences between the groups with or without adhesive. CONCLUSIONS The polymerization behavior of the core build-up resins was affected by the power density of the curing unit. The influence of adhesive application differed among the core build-up resins tested.
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Affiliation(s)
- Noriatsu Sunada
- Department of Operative Dentistry, Nihon University School of Dentistry, Kanda-Surugadai, Chiyoda-ku, Tokyo, Japan
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Jeong CM, Heo YJ, Jeon YC, Kim HI, Kwon YH. Microhardness and polymerization shrinkage of flowable resins that are light cured using a blue laser. Lasers Med Sci 2012; 27:729-33. [PMID: 21786140 DOI: 10.1007/s10103-011-0964-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 07/07/2011] [Indexed: 11/27/2022]
Abstract
This study evaluated the microhardness and polymerization shrinkage of flowable resins that are cured using different light sources. Seven flowable resins and two light sources (diode-pumped solid-state (DPSS) laser (LAS) and Optilux 501 (OP)) were chosen for the study. To evaluate the microhardness, a mold (height: 2 mm, inner diameter: 4 mm) was filled with resin and then light cured. The microhardness was measured at the top and bottom surfaces after aging for 24 h. The level of polymerization shrinkage was evaluated for 130 s (during and after the light curing) by measuring the dimensions of the cylindrical shape resin filling. The light intensity of the LAS and OP was approximately 520 mW/cm(2) and 800 mW/cm(2), respectively. The data for the microhardness and polymerization shrinkage were analyzed statistically. The microhardness (Hv) of the specimens at the top and bottom surface ranged from 25.3 ± 0.6 to 55.3 ± 1.0 and 28.0 ± 2.6 to 63.0 ± 2.3, respectively. Admira flow, Grandio flow, and Filtek Z350 flow showed a slightly higher microhardness at the bottom surface than that at the top surface. The degree of polymerization shrinkage (μm) of the specimens ranged from 30.5 ± 1.3 to 45.9 ± 0.6 for LAS and from 35.1 ± 1.5 to 47.1 ± 1.0 for OP. The values obtained using LAS and OP showed a statistical difference, but in many cases, the difference between the absolute values was minor.
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Affiliation(s)
- Chang-Mo Jeong
- Department of Prosthodontics Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea
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Park JK, Yun DI, Hur B, Kim HI, Kwon YH. Influence of Blue Laser on Water Sorption and Solubility of Flowable Resins. Photomed Laser Surg 2010; 28:779-84. [DOI: 10.1089/pho.2009.2714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jeong-Kil Park
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Korea
| | - Dong-In Yun
- Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, Korea
| | - Bock Hur
- Department of Conservative Dentistry, School of Dentistry, Pusan National University, Korea
| | - Hyung-Il Kim
- Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, Korea
| | - Yong Hoon Kwon
- Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, Korea
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Jung YH, Cho BH, Nah KS, Kim HI, Kwon YH. Effect of diode-pumped solid state laser on polymerization shrinkage and color change in composite resins. Lasers Med Sci 2010; 25:339-43. [PMID: 19205788 DOI: 10.1007/s10103-009-0644-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Accepted: 01/10/2009] [Indexed: 11/25/2022]
Abstract
A diode-pumped solid state (DPSS) laser emitting at 473 nm was used to test its influence on the degree of polymerization of composite resins. Eight composite resins were chosen and light cured with three different light-curing systems [a quartz-tungsten-halogen (QTH) lamp-based unit, a light-emitting diode (LED) unit, and a DPSS laser]. Polymerization shrinkage and color change in specimens were measured. According to the statistical analysis, each light-curing system produced a significantly different value of maximum polymerization shrinkage. In most specimens, the DPSS laser induced the least polymerization shrinkage. After being immersed in distilled water for 10 days, specimens light-cured by the DPSS laser had undergone less color change than those cured by the other units. In conclusion, the DPSS laser induced better or similar polymerization in terms of polymerization shrinkage and color change in composite resins compared with those of the QTH lamp-based and LED units.
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Affiliation(s)
- Yun-Hoa Jung
- College of Dentistry and Medical Research Institute, Pusan National University, Busan, South Korea
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Cassoni A, Ferla JDO, Albino LGB, Youssef MN, Shibli JA, Rodrigues JA. Argon ion laser and halogen lamp activation of a dark and light resin composite: microhardness after long-term storage. Lasers Med Sci 2009; 25:829-34. [DOI: 10.1007/s10103-009-0708-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
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Piva E, Correr-Sobrinho L, Sinhoreti MAC, Consani S, Demarco FF, Powers JM. Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement. J Appl Oral Sci 2009; 16:189-93. [PMID: 19089216 PMCID: PMC4327692 DOI: 10.1590/s1678-77572008000300005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 02/28/2008] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm-2 (I/2x2T), 24 Jcm-2 (IxT) and 48 Jcm-2 (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (α=5%). Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8) and HAL (50.9±3.7) produced significantly higher KHN means (p<0.05) than the control (44.7±3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.
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Affiliation(s)
- Evandro Piva
- Department of Restorative Dentistry, Dental School, Federal University of Pelotas, Pelotas, RS, Brazil.
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Bhamra GS, Fleming GJ. Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials. Dent Mater 2009; 25:214-20. [DOI: 10.1016/j.dental.2008.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 06/19/2008] [Accepted: 06/20/2008] [Indexed: 11/27/2022]
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Cassoni A, Ferla JDO, Shibli JA, Kawano Y. Knoop Microhardness and FT-Raman Spectroscopic Evaluation of a Resin-Based Dental Material Light-Cured by an Argon Ion Laser and Halogen Lamp: Anin VitroStudy. Photomed Laser Surg 2008; 26:531-9. [DOI: 10.1089/pho.2007.2212] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Alessandra Cassoni
- Department of Restorative Dentistry, Guarulhos University, Guarulhos, Brazil
| | | | - Jamil Awad Shibli
- Department of Periodontology, Guarulhos University, Guarulhos, Brazil
| | - Yoshio Kawano
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
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12
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Bhamra GS, Fleming GJ. Effects of halogen light irradiation variables (tip diameter, irradiance, irradiation protocol) on flexural strength properties of resin-based composites. J Dent 2008; 36:643-50. [DOI: 10.1016/j.jdent.2008.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 04/23/2008] [Accepted: 04/24/2008] [Indexed: 11/24/2022] Open
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Kwon YH, Jang CM, Shin DH, Seol HJ, Kim HI. The applicability of DPSS laser for light curing of composite resins. Lasers Med Sci 2007; 23:407-14. [PMID: 17902013 DOI: 10.1007/s10103-007-0496-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Accepted: 08/30/2007] [Indexed: 11/26/2022]
Abstract
The applicability of diode-pumped solid state (DPSS) laser for light curing the composite resins was tested with a quartz-tungsten-halogen lamp-based unit and a light emitting diode unit. The emission spectra of the light-curing systems used match with the absorption spectrum of camphorquinone. Among the light-curing systems, DPSS laser showed the narrowest emission bandwidth. The light intensity of DPSS laser was approximately 64% of the other two light-curing units. In most specimens, DPSS laser showed the least attenuation of the number of incident photons. On the top surface, specimens cured with DPSS laser showed similar microhardness values compared to the specimens cured with the other two light-curing units. During the light curing, DPSS laser induced the lowest temperature rise (25.5-35.5 degrees C) in the specimens compared to the other two light-curing units (34.2-41.7 degrees C). In conclusion, DPSS laser has high potential to be an alternative to the other light-curing units or a new light-curing unit.
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Affiliation(s)
- Yong Hoon Kwon
- Department of Dental Materials, Medical Research Institute and College of Dentistry, Pusan National University, Busan 602-739, Korea.
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Ritter AV, Cavalcante LM, Swift EJ, Thompson JY, Pimenta LA. Effect of light-curing method on marginal adaptation, microleakage, and microhardness of composite restorations. J Biomed Mater Res B Appl Biomater 2006; 78:302-11. [PMID: 16615068 DOI: 10.1002/jbm.b.30488] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The objective of this study was to investigate the effects of different light-curing methods on microleakage, marginal adaptation, and microhardness of composite restorations. Slot-type preparations were made in bovine teeth, with gingival margins on dentin. Specimens were divided into 12 groups (n = 12) according to composite-light-curing unit (LCU) combinations. Three composites were used: Filtek Supreme, Herculite XRV, and Heliomolar. All restorations were placed using the same adhesive. Four LCUs were used: a quartz-tungsten-halogen (QTH) LCU (Optilux 501), a first-generation light-emitting diode (LED) LCU (FreeLight 1), and two second-generation LED LCUs (FreeLight 2 and Translux Power Blue). After finishing and polishing, specimens were subjected to mechanical load cycling (100,000 cycles). Gingival margin adaptation was determined as a function of gap formation using epoxy replicas. Microleakage was evaluated by measuring dye penetration across the gingival wall in cross-sectioned specimens. Microhardness was measured as Knoop Hardness number (KHN) at different occluso-gingival locations in cross-sectioned specimens. Data were analyzed for statistical significance (p = 0.05) using appropriate statistical tests. Marginal adaptation was affected by load-cycling in most specimens, but no significant differences were observed among composites and LCUs. Microleakage was not affected by LCU, except for Heliomolar specimens which when cured with Optilux 501 resulted in higher microleakage scores than those obtained with the other LCUs. For microhardness, Translux Power Blue generally produced the highest values and the FreeLight 1 produced the lowest. The performance of the second-generation LED LCUs generally was similar to that of the QTH control, and better than that of the first-generation LED unit.
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Affiliation(s)
- André V Ritter
- Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, USA
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Tarle Z, Knezevic A, Demoli N, Meniga A, Sutaloa J, Unterbrink G, Ristic M, Pichler G. Comparison of Composite Curing Parameters: Effects of Light Source and Curing Mode on Conversion, Temperature Rise and Polymerization Shrinkage. Oper Dent 2006; 31:219-26. [PMID: 16827025 DOI: 10.2341/05-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Clinical Relevance
The use of a low intensity light source for photopolymerization based on LED technology provides equivalent final degree conversion with possible flow of the resin composite, similar to when QTH technology is used. At the same time, the lower temperature rise in the sample and the more favorable development of shrinkage kinetics compared to the higher intensities of halogen light may aid in maintaining marginal adaptation while avoiding possible thermal injury.
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Affiliation(s)
- Zrinka Tarle
- Department of Dental Pathology, School of Dental Medicine, University of Zagreb, Zagreb, Croatia.
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16
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Cassoni A, Youssef MN, Prokopowitsch I. Bond strength of a dentin bonding system using two techniques of polymerization: visible-light and argon laser. Photomed Laser Surg 2006; 23:493-7. [PMID: 16262580 DOI: 10.1089/pho.2005.23.493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE The aim of this work was to study one dentin-bonding system associated with posterior teeth restorative composite resin by means of tensile bond strength tests varying the technique of polymerization: visible light and argon laser. BACKGROUND DATA Previous studies have demonstrated the ability of the argon laser to polymerize light-activated materials. METHODS Sixty specimens were prepared by grinding the labial surface of bovine teeth embedded in acrylic resin. The dentin bonding system used was Single Bond (3M), which has a poliacenoic acid copolimer, associated with a posterior teeth restorative composite resin (Filtek P60, 3M). The bonding sites were treated according to the instruction of the manufacturers. The 60 teeth, duly embedded and ground, were assigned to four groups with 15 teeth each: group 1, the adhesive was light cured during 10 sec with visible light (Curing Light, 3M) with power density of 410 mW/cm2 and the composite resin was light cured during 20 sec with visible light; group 2, the adhesive and the composite resin were cured during 10 seconds with argon laser with 150 mW of power; group 3, the adhesive and the composite resin were cured during 10 sec with argon laser with 200 mW of power; and group 4, the adhesive and the composite resin were cured during 10 sec with argon laser with 250 mW of power. The composite resin was light cured in layers of 1 mm of thickness until the model of teflon with 3 mm in height was completely filled. RESULTS The tensile bond strength test was performed in a Mini-Instron (model 4442) and the results for group 1 were 19.75 MPa (+/-4.65), group 2 were 16.09 MPa (+/-7.27), group 3 were 11.56 MPa (+/-4.50), and group 4 were 11.90 MPa (+/-5.78). CONCLUSIONS One can conclude that the tensile bond strength promoted by the polymerization with visible light presented greater tensile bond strength than the polymerization with argon laser with 200 mW and 250 mW, but there was no significant difference between visible light and argon laser with 150 mW. There was no significant difference between argon laser with 150 mW and argon laser with 200 mW or 250 mW.
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Affiliation(s)
- Alessandra Cassoni
- Department of Restorative Dentistry, University of São Paulo, São Paulo, Brazil.
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Koupis NS, Martens LC, Verbeeck RMH. Relative curing degree of polyacid-modified and conventional resin composites determined by surface Knoop hardness. Dent Mater 2006; 22:1045-50. [PMID: 16388844 DOI: 10.1016/j.dental.2005.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 07/19/2005] [Accepted: 08/10/2005] [Indexed: 11/21/2022]
Abstract
OBJECTIVES The aim of the present study was to investigate the relative curing degree at a depth of 2 mm of several polyacid-modified composites (PAM-Cs) as a function of shade. METHODS The Knoop hardness of the irradiated top and non-irradiated bottom surfaces of 2 mm thick samples of the PAM-Cs Hytac, F2000, Glasiosite, Dyract, Dyract AP, and Compoglass F and of the resin composites Z100, Herculite Enamel XRV, and Durafill VS, were determined for shades A2 and A4. RESULTS The top and bottom hardness of F2000 and Glasiosite ranged between that of the two composites Herculite and Z100. Compoglass, Dyract and Dyract AP had a lower top and bottom hardness than the hybrid composites, but higher than that of the microfilled composite Durafill. The top hardness of Hytac compared with that of the first group, whereas the bottom hardness compared with the second group. The bottom-to-top KHN ratio reflecting the relative curing degree at a depth of 2 mm was less than 80% for the two shades of Hytac and Compoglass as well as for the A4 shade of Dyract AP and Herculite. SIGNIFICANCE A hard top surface of a PAM-C is not an indication of adequate in depth polymerization. Shade A2 results in significantly greater values for the curing degree compared to shade A4, the effect depending quantitatively on the formulation of the material. Some formulations of PAM-C do not reach an adequate curing degree at a depth of 2 mm so that it is recommended to apply the incremental technique even in box-only cavities with layers of maximum 2 mm.
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Affiliation(s)
- Nikolaos S Koupis
- Department of Paediatric Dentistry, PAECAMED, Ghent University, Gent, Belgium
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Chen YC, Ferracane JL, Prahl SA. A pilot study of a simple photon migration model for predicting depth of cure in dental composite. Dent Mater 2005; 21:1075-86. [PMID: 16085305 DOI: 10.1016/j.dental.2005.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Revised: 04/18/2005] [Accepted: 05/10/2005] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The purpose of this study was to build a photo migration model to calculate the radiant exposure (irradiancextime) in dental composite and to relate the radiant exposure with extent of cure using polymer kinetics models. METHODS A composite (Z100, Shade A2) cylinder (21 mm diameter by 15 mm deep) was cured with a tungsten-halogen lamp emitting 600 mW/cm2, 1 mm above the composite for 60s. For each of the 2x1 mm grids along the longitudinal cross section (diameter versus depth), the degree of conversion (DC) and hardness (KHN) were measured to construct the curing extent distribution. The inverse adding-doubling method was used to characterize the optical properties of the composite for the Monte Carlo model simulating the photon propagation within the composite cylinder. The calculated radiant exposure (H) distribution along the cross section was related to the curing extent DC/DC(max) distribution and fitted with two polymer curing kinetics models, the exponential model DC=DC(max)[1-exp((ln0.5)H/H(dc)(50%))] and Racz's model [Formula: see text] , where H(dc)(50%) is a fitting parameter representing the threshold for 50% of the maximum curing level. RESULTS AND SIGNIFICANCE The absorption and scattering coefficients of uncured composite were higher than that of cured composite at wavelengths between 420 and 520 nm. A roughly hemi-spheric distribution of radiant exposure in the Monte Carlo simulation result was comparable with the curing profiles determined by both DC and KHN. The relationship between DC (or KHN) and H agreed with the Racz model (r2=0.95) and the exponential model (r2=0.93). The H(dc)(50%) was 1.5(0.1), equal for the two models (P<0.05). The estimated radiant exposure threshold for 80% of the maximum curing level was between 3.8 and 8.8 J/cm2. The simulation results verify that the radiant exposure extends to a greater depth and width for composite with lower absorption and scattering coefficients. Given the optical properties and the geometry of the composite, and the spectrum and the geometry of the light source, the Monte Carlo simulation can accurately describe the radiant exposure distribution in a composite material to predict the extent of cure.
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Affiliation(s)
- Yin-Chu Chen
- Department of Biomedical Engineering, OHSU, 9205 SW Barnes Rd., Portland, OR 97225, USA
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Thind BS, Stirrups DR, Lloyd CH. A comparison of tungsten-quartz-halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive. Eur J Orthod 2005; 28:78-82. [PMID: 16199410 DOI: 10.1093/ejo/cji076] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study investigated whether there were differences between the debond stress and adhesive remnant index (ARI) of an adhesive cured with three different orthodontic light sources. Sixty sound premolar teeth were divided into three groups of 20. A standard pre-adjusted edgewise premolar bracket (Victory Series) was bonded to each tooth using a light-cured orthodontic adhesive, Transbond X. Group 1 (control) specimens were cured with an Ortholux XT (tungsten-quartz-halogen bulb) light for 20 seconds, group 2 with an Ortho lite (plasma arc) for 6 seconds and group 3 with an Ortholux LED light-emitting diode for 10 seconds. The specimens were debonded 24 hours later using a universal mechanical testing machine, operating at a crosshead speed of 0.5 mm minute(-1). The Weibull modulus and a Logrank test showed no statistically significant differences between the three groups for debond stress. The ARI was assessed at x10 magnification. The ARI scores for group 2 were significantly different (P < 0.01) from those of groups 1 and 3 (between which there was no significant difference). For group 2 there was a greater tendency for failure to occur at the adhesive/tooth interface than for the other two groups. There appears to be no reason why any of the three types of light source cannot be used in orthodontics. Polymerization, as effective as that produced by conventional bulb light sources, was obtained with the short exposure times recommended for the plasma arc or light-emitting diode sources.
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Affiliation(s)
- Bikram S Thind
- Department of Orthodontics and Restorative Dentistry, Glenfield Hospital, Leicester, UK.
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Hodson NA, Dunne SM, Pankhurst CL. The effect of infection-control barriers on the light intensity of light-cure units and depth of cure of composite. PRIMARY DENTAL CARE : JOURNAL OF THE FACULTY OF GENERAL DENTAL PRACTITIONERS (UK) 2005; 12:61-7. [PMID: 15901434 DOI: 10.1308/1355761053695149] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
AIM Dental curing lights are vulnerable to contamination with oral fluids during routine intra-oral use. This controlled study aimed to evaluate whether or not disposable transparent barriers placed over the light-guide tip would affect light output intensity or the subsequent depth of cure of a composite restoration. METHODS The impact on light intensity emitted from high-, medium- and low-output light-cure units in the presence of two commercially available disposable infection-control barriers was evaluated against a no-barrier control. Power density measurements from the three intensity light-cure units were recorded with a radiometer, then converted to a digital image using an intra-oral camera and values determined using a commercial computer program. For each curing unit, the measurements were repeated on ten separate occasions with each barrier and the control. Depth of cure was evaluated using a scrape test in a natural tooth model. RESULTS At each level of light output, the two disposable barriers produced a significant reduction in the mean power density readings compared to the no-barrier control (P<0.005). The cure sleeve inhibited light output to a greater extent than either the cling film or the control (P<0.005). Only composite restorations light-activated by the high level unit demonstrated a small but significant decrease in the depth of cure compared to the control (P<0.05). CONCLUSION Placing disposable barriers over the light-guide tip reduced the light intensity from all three curing lights. There was no impact on depth of cure except for the high-output light, where a small decrease in cure depth was noted but this was not considered clinically significant. Disposable barriers can be recommended for use with light-cure lights.
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Affiliation(s)
- Nicholas A Hodson
- Department of Primary Dental Care, GKT Dental Institute, London SE5 9RW, UK.
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