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Phan AC, Béhin P, Stoclet G, Dorin Ruse N, Nguyen JF, Sadoun M. Optimum pressure for the high-pressure polymerization of urethane dimethacrylate. Dent Mater 2015; 31:406-12. [DOI: 10.1016/j.dental.2015.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 12/20/2014] [Accepted: 01/12/2015] [Indexed: 11/28/2022]
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KHERAIF AAAA, QASIM SSB, RAMAKRISHNAIAH R, REHMAN IU. Effect of different beverages on the color stability and degree of conversion of nano and microhybrid composites. Dent Mater J 2013; 32:326-31. [DOI: 10.4012/dmj.2011-267] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Carioscia JA, Lu H, Stanbury JW, Bowman CN. Thiol-ene oligomers as dental restorative materials. Dent Mater 2005; 21:1137-43. [PMID: 16046232 DOI: 10.1016/j.dental.2005.04.002] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Accepted: 04/07/2005] [Indexed: 01/19/2023]
Abstract
OBJECTIVE The aim of this work was to prereact thiol-ene monomers to create reactive thiol or vinyl (ene)-functionalized oligomers, and to investigate the use of these materials as novel dental restorative material. Investigation has focused on the application of oligomeric thiol-ene materials as dental restorative resins with lower polymerization shrinkage and polymerization stress as compared to monomeric thiol-ene systems and particularly with respect to current dimethacrylate-based systems. METHODS Reactive thiol-functionalized oligomers were created via photopolymerization using triallyl-1,3,5-triazine-2,4,6-trione (TATATO), trimethylolpropane tris(3-mercaptopropionate) (trithiol) and pentaerythritol tetramercaptopropionate (tetrathiol). Kinetic and mechanical investigation of Bis-GMA/TEGDMA, and oligomeric and monomeric thiol-ene systems were conducted. More specifically, polymerization shrinkage and stress, polymerization kinetics, glass transition temperature, flexural strength and flexural modulus were evaluated. RESULTS Upon evaluation, the polymerization stress of oligomeric thiol-ene systems was dramatically reduced by as much as 33% when compared with the stress exhibited by monomeric thiol-ene systems and as much as a 92% reduction in stress relative to the current dimethacrylate-based dental restorative materials. Furthermore, the flexural strength and modulus of the monomeric and oligomeric thiol-ene resins were not significantly different. SIGNIFICANCE Oligomeric thiol-ene systems offer potential as alternative dental restorative resins due to the significant reduction in polymerization shrinkage and stress while retaining the mechanical properties of monomer-based thiol-ene resins.
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Affiliation(s)
- Jacquelyn A Carioscia
- Department of Chemical and Biological Engineering, Engineering Center, University of Colorado at Boulder, ECCH 111, 80309-0424, USA
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Soares LES, Martin AA, Pinheiro ALB, Pacheco MTT. Vicker's hardness and Raman spectroscopy evaluation of a dental composite cured by an argon laser and a halogen lamp. JOURNAL OF BIOMEDICAL OPTICS 2004; 9:601-608. [PMID: 15189099 DOI: 10.1117/1.1688811] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present the results of the Vicker's hardness test and the use of near-infrared Raman spectroscopy (RS) to measure in vitro the degree of conversion (DC) of a bis(phenol)-A-glycidyl-dimethacrylate-based composite resin, photoactivated by both a halogen lamp (power density=478 mW/cm(2); 8-mm diameter spot) and an argon laser (power density=625 mW/cm(2); 7-mm diameter spot). The degree of conversion was estimated by analyzing the relative intensities between the aromatic C=C stretching Raman mode at 1610 cm(-1) and the methacrylate C=C stretching Raman mode (1640 cm(-1)) on top and bottom surfaces. For the hardness evaluation, the samples were embedded in polyester resin and three indentations with a 50-g load for 10 s were made on the top surface. The higher relative DC values achieved by the photoactivation of a composite resin by the argon laser suggest a better biocompatibility in the bottom surface. The correlation test showed that the higher Vicker's hardness number (VHN) values were associated with higher DC values. The derivative analysis showed a greater curing rate from 5 to 20 s of exposure. The comparison of VHN and DC values with both light sources at each curing time showed that a small change in conversion is related to a large change in hardness. Raman spectroscopy is more sensitive to changes in the first stages of curing reaction than later ones, and the Vicker's hardness assay is more sensitive to changes in the last stages.
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Affiliation(s)
- Luís Eduardo Silva Soares
- University of Vale do Paraaiba-UNIVAP, School of Dentistry, Laboratorio de Espectroscopia Vibracional Biomedical, Av. Shishima Hifumi, 2911, Urbanova-CEP 12.224-000, Sao Jose dos Campos, Sao Paulo, Brazil
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Silva Soares LE, Martin AA, Barbosa Pinheiro AL. Degree of conversion of composite resin: a Raman study. ACTA ACUST UNITED AC 2004; 21:357-62. [PMID: 14709220 DOI: 10.1089/104454703322650167] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Near infrared Raman spectroscopy (RS) was used to monitor, in vitro, the degree of conversion (DC) of composite resins (Z100, 3M), photoactivated by both the halogen lamp and the argon laser beam. BACKGROUND DATA Several methods were used to study the alterations of composite resins. Vibration methods such as RS allow a precise assessment of the depth of polymerization and the degree of conversion of composite resins. MATERIALS AND METHODS Sixty circular blocks of resin (7 mm x 2.5 mm) were cured using a halogen light source (n=30, lambda=400-500 nm, power density=478 mW/cm2) or an argon laser beam (n=30, lambda=488 nm, power density=625 mW/cm2) using the same irradiation time (5, 10, 20, 30, 40, and 60 sec). The directly irradiated (top) and the non-irradiated (bottom) surfaces were analyzed immediately after curing by Raman spectroscopy. RESULTS The Raman results show systematic changes of the relative intensities between the peaks at 1610 (aromatic C=C stretching mode) and the 1640 cm(-1) (methacrylate C=C stretching mode), as a function of irradiation time. After 60 sec of irradiation time, the maximum degree of conversion reached for the samples cured either by the argon laser or halogen lamp was 66.4% and 62.2%, respectively. CONCLUSION The argon laser was more effective and showed better biocompatibility, with less residual monomer in the bottom (2.5 mm). These results show that RS can be used as an effective method to study the degree of conversion of composite resins.
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Affiliation(s)
- Luís Eduardo Silva Soares
- School of Dentistry, Research and Development Institute, IP&D, UNIVAP, São José dos Campos, SP, Brazil.
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Fan PL, Schumacher RM, Azzolin K, Geary R, Eichmiller FC. Curing-light intensity and depth of cure of resin-based composites tested according to international standards. J Am Dent Assoc 2002; 133:429-34; quiz 491-3. [PMID: 11991459 DOI: 10.14219/jada.archive.2002.0200] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Several factors control the light curing of a resin-based composite: the composition of the composite, the shade of the composite, the wavelength and bandwidth of the curing light, the distance of the light from the composite, the intensity of the curing light and the irradiation time. The authors investigated the depth of cure of several shades of five brands of resin-based composites when irradiated via light in the 400- to 515-nanometer wavelength bandwidth at the International Organization for Standardization, or ISO, recommended intensity of 300 milliwatts per square centimeter. The resin-based composites were irradiated for the times recommended by the products' manufacturers. METHODS The authors used a curing light adjusted to emit 300 mW/cm2 in the 400-nm to 515-nm wavelength bandwidth to polymerize five samples of each composite brand type and shade. They measured depth of cure using a scraping method described in the ISO standard for resin-based composites. Depth of cure was defined as 50 percent of the length of the composite specimen after uncured material was removed by manual scraping. The authors determined a mean from the five samples of each composite brand and shade. RESULTS Thirteen (62 percent) of 21 composite materials met the ISO standard depth-of-cure requirement of 1.5 millimeters. Six of the eight remaining materials met the depth-of-cure requirement when the authors doubled the irradiation time recommended by the product manufacturers. CONCLUSIONS AND CLINICAL IMPLICATIONS Curing lights with an intensity of 300 mW/cm2 appear to effectively cure most resin-based composite materials when appropriate curing times are used, which, in some cases, are longer than those recommended by the manufacturers. Dentists should verify the depth of cure of a composite material as a baseline measure, and then check depth of cure periodically to confirm light and material performance. The ISO depth-of-cure measurement method can be used for this purpose.
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Affiliation(s)
- P L Fan
- Division of Science, American Dental Association, Chicago, IL 60611, USA.
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Lloyd CH, Scrimgeour SN, Chudek JA, Hunter G, MacKay RL. The application of magnetic resonance microimaging to the visible light curing of dental resins. Part 2. Dynamic imaging by the FLASH-MOVIE pulse sequence. Dent Mater 2001; 17:170-7. [PMID: 11163388 DOI: 10.1016/s0109-5641(00)00063-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES To investigate the application of a rapid NMR imaging pulse sequence, FLASH-MOVIE, to the visible light curing of dental restorative materials. METHODS The light guide was applied at one end of a cylindrical specimen of visible light curing unfilled resin and the light directed along the cylinder. During polymerisation an NMR imaging pulse sequence, FLASH-MOVIE, was run at 15s intervals with a 50 ms repetition time. The image of a 1mm thick vertical slice was recorded with a (125 microm)2 pixel size. RESULTS Images with good contrast were obtained from all resin monomers. The image intensity from the polymer was indistinguishable from the background intensity. Thus, the progress of light activated polymerisation in the material could be followed in real time through a series of up to 16 images. Initially the image intensity increased in the material closest to the light guide, then decreased over time to zero. Concomitant with this fall, a "cure-front" moved through the specimen. SIGNIFICANCE The FLASH-MOVIE NMR pulse sequence applied to microimaging of dental diacrylate resins can be used to obtain a dynamic record of visible light curing. A more refined experimental protocol will be required to apply this unique data to models proposed for this polymerisation mechanism.
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Affiliation(s)
- C H Lloyd
- Dental School, University of Dundee, DD1 4HN, Dundee, UK.
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Burkoth AK, Anseth KS. A review of photocrosslinked polyanhydrides: in situ forming degradable networks. Biomaterials 2000; 21:2395-404. [PMID: 11055287 DOI: 10.1016/s0142-9612(00)00107-1] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many orthopaedic injuries could benefit from a high-strength and degradable material with good tissue compatibility. In addition, there is a great clinical need for materials which are easily contoured or placed into complex-shaped defects by a surgeon. We have rationally designed a new class of photocrosslinkable polyanhydride monomers which in situ form high-strength and surface eroding networks of complex geometries. This paper highlights the advantages of these materials for orthopaedic applications and the technique of photopolymerization for reacting these monomers under physiological conditions. The rationale for the material design, photopolymerization kinetics, degradation behavior, and histology in subcutaneous tissue and a model bone defect are presented.
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Affiliation(s)
- A K Burkoth
- Department of Chemical Engineering, University of Colorado Campus Box 424, Boulder 80309-0424, USA
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Peutzfeldt A, Sahafi A, Asmussen E. Characterization of resin composites polymerized with plasma arc curing units. Dent Mater 2000; 16:330-6. [PMID: 10915894 DOI: 10.1016/s0109-5641(00)00025-7] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES Newly developed curing units (plasma arc curing units) operate at relatively high intensity and are claimed to result in optimum properties of resin composites in a short cure time. This study was conducted to determine a number of characteristics of resin composites polymerized by plasma arc curing units. METHODS The investigated polymerization characteristics were quantity of remaining double bonds, depth of polymerization, flexural strength and modulus, and wall-to-wall polymerization contraction. The investigated plasma arc curing units were Apollo 95E and 1000 PAC. The conventional curing unit XL 3000 was used as baseline. RESULTS Irradiation with Apollo 95E resulted in a higher quantity of remaining double bonds than did XL 3000, whereas the results obtained with 1000 PAC depended on the resin composite. The depth of cure with the plasma arc units was equal to or less than that obtained with the conventional unit, depending on the resin composite. The flexural strength did not depend on the curing unit. The flexural modulus resulting from curing with Apollo 95E was less than that resulting from curing with XL 3000 in 3 out of 4 comparisons. The wall-to-wall polymerization contraction was equal to or less with the plasma arc units than with the conventional unit. SIGNIFICANCE Plasma arc curing units make it possible to polymerize resin composite in much shorter times than conventional curing units. However, the polymerization characteristics associated with the units may be less than optimal.
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Affiliation(s)
- A Peutzfeldt
- Department of Dental Materials, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
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SANTOS LA, TURBINO ML, YOUSSEF MN, MATSON E. Microdureza de resina composta: efeito de aparelhos e tempos de polimerização em diferentes profundidades. ACTA ACUST UNITED AC 2000. [DOI: 10.1590/s1517-74912000000100012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As propriedades das resinas compostas têm sido estudadas com freqüência, bem como os fatores que podem influenciar seu grau de polimerização. Diante da evolução desses materiais e da necessidade de buscarmos melhora do seu comportamento na cavidade bucal, objetivamos, por meio deste estudo avaliar a eficácia de dois aparelhos fotopolimerizadores do tipo pistola (de alta intensidade de luz), comparando com a de um aparelho a cabo (de baixa intensidade de luz), com tempos de exposição de 20 e de 40 segundos e em profundidades de 1 a 4 milímetros. Os testes avaliaram o grau de polimerização da resina por meio de testes de microdureza Knoop. Os resultados mostraram haver diferença estatisticamente significante entre os tempos, sendo que com 40 segundos a dureza foi maior que com 20 segundos para as 4 diferentes profundidades. Para o fator aparelhos, os dois aparelhos tipo pistola se comportaram superiores ao do tipo cabo Fibralux (Dabi Atlante), e entre eles, o XL 1500 (3M) promoveu dureza maior que o Optilight II (Gnatus) no tempo de polimerização de 40 segundos. As profundidades de 1, 2, 3 e 4 milímetros mostraram estatisticamente diferença entre si tendo sido encontrada maior dureza para as menores profundidades (p < 0,05).
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Pianelli C, Devaux J, Bebelman S, Leloup G. The micro-Raman spectroscopy, a useful tool to determine the degree of conversion of light-activated composite resins. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1999; 48:675-81. [PMID: 10490681 DOI: 10.1002/(sici)1097-4636(1999)48:5<675::aid-jbm11>3.0.co;2-p] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Light-activated composites are now among the most popular dental restorative materials. Nevertheless, concerns exist about the so-called depth of cure. Infrared spectroscopy (FTIR) has traditionally been used to quantify this problem by evaluating the degree of conversion of dental resins. However, Raman scattering provides an alternate method. This article describes the advantages and the limitations of micro-Raman spectroscopy, as compared to FTIR and other techniques, for calculating the local degree of conversion and the depth of cure of light-cured composites.
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Affiliation(s)
- C Pianelli
- Université catholique de Louvain, Laboratoire de Physique et de Chimie des Hauts Polymères, Place Croix du Sud, 1, B-1348 Louvain-la-Neuve, Belgium
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Mizrahi E, Cleaton-Jones P, Landy C. Tooth surface and pulp chamber temperatures developed during electrothermal bonding. Am J Orthod Dentofacial Orthop 1996; 109:506-14. [PMID: 8638595 DOI: 10.1016/s0889-5406(96)70135-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The rationale of electrothermal bonding is based on the premise that when an electric current is passed across the beaks of tweezers holding a stainless steel orthodontic bracket, heat will be generated by virtue of the electrical resistance of the steel bracket. This study was carried out to evaluate the temperatures generated on the tooth surface at the bracket/tooth interface and within the pulp chamber during electrothermal bonding. Temperatures were recorded with 5 and 7.5 A current levels applied as a 1 second pulse with time intervals between pulses of 1, 2, 3, and 4 seconds. The data showed that after three pulses with a 5 A current, the temperature on the tooth surface ranged between 43.3 degrees C (4 second intervals) to 53.6 degrees C (1 second intervals). By using a 7.5 A current, the temperature ranged from 77.5 degrees C (4 second intervals) to 85.9 degrees C (1 second intervals). The pulp chamber temperatures were evaluated in vitro for a mandibular incisor, the maxillary central and lateral incisors, a canine, a premolar, and a molar. The pulp chamber temperature of a mandibular incisor responded most, whereas that of premolars and molars responded least to temperature changes on the labial surface. The increase in mandibular incisor pulp chamber temperature after three pulses was 2.1 degrees C for 5 A and 2.8 degrees C for 7.5 A current while for a premolar the increase ranged from 0.9 degree C to 1.6 degrees C. On the basis of current evidence the increase in pulp chamber temperatures during electrothermal bonding may be considered to be clinically safe.
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Affiliation(s)
- E Mizrahi
- Department of Orthodontics, University of Witwatersrand, Johannesburg, South Africa
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13
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Anseth KS, Newman SM, Bowman CN. Polymeric dental composites: Properties and reaction behavior of multimethacrylate dental restorations. BIOPOLYMERS II 1995. [DOI: 10.1007/3540587888_16] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Kawaguchi M, Fukushima T, Miyazaki K. The relationship between cure depth and transmission coefficient of visible-light-activated resin composites. J Dent Res 1994; 73:516-21. [PMID: 8120215 DOI: 10.1177/00220345940730020601] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The relationships between the transmission coefficient and the cure depth were evaluated on eight commercially available light-activated resin composites. The determination of transmission coefficient was carried out by the use of a radiometer for various shades of the resin composites. The transmission coefficient, ranging from 0.042 to 0.263, was dependent upon the shade of the resin. There was a good correlation between the transmission coefficient and the cure depth for different shades for each resin composite, except for one hybrid resin composite (P-50). The microfilled resin composite showed transmission coefficient and cure depth lower than those of the hybrid and small-particle-filled resin composites.
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Affiliation(s)
- M Kawaguchi
- Department of Dental Materials and Devices, Fukuoka Dental College, Japan
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15
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Wang WN, Meng CL. A study of bond strength between light- and self-cured orthodontic resin. Am J Orthod Dentofacial Orthop 1992; 101:350-4. [PMID: 1532686 DOI: 10.1016/s0889-5406(05)80328-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Light-cured orthodontic composite resin has been widely advertised recently for use in bonding. However, the curability of light-cured resin when light waves are diffused through metal, ceramic, or resin brackets is doubtful and questionable. This study evaluated the effectiveness of a visible light source in curing the resin under a solid metal bracket, compared the tensile bond strength at different exposures, and analyzed the broken interface distribution between light-cured resin with various light exposure times and self-cured resin. The bond strength results revealed that the difference between light-cured resin (Transbond) with 60, 40, and 20 seconds of light exposure, respectively, and self-cured resin (Concise) was 1.05, 0.92, 0.61, and 0.71 kg/mm2, respectively. The bond strength of Transbond with 60 and 40 seconds of light exposure was greater than both the bond strength of Transbond with 20 seconds of light exposure and the strength of the self-cured resin of Concise, with statistical significance (p less than 0.01). There were also no statistical differences between Transbond with 60 and 40 seconds of light exposure or Transbond with 20 seconds of light exposure and Concise. The bond failure interfaces were located between the bracket and the resin, within the resin itself, or between the resin and the enamel. Tooth fragmentation was rarely found. There were no statistical differences (p greater than 0.05) among broken interfaces. This indicates that visible light is powerful in curing the visible light-activated composite resin under solid metal brackets.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W N Wang
- Department of Dentistry, Tri-Service General Hospital, Taipei, Taiwan, Republic of China
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16
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Atmadja G, Bryant RW. Some factors influencing the depth of cure of visible light-activated composite resins. Aust Dent J 1990; 35:213-8. [PMID: 2393355 DOI: 10.1111/j.1834-7819.1990.tb05394.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Some of the factors influencing the depth of cure of four composite resins of different composition were examined. Knoop hardness measurements were carried out at the surface and 1, 2, 3, 4 and 6 mm below the surface to which the light was applied. The hardness of the composites decreased with increasing depth and shorter exposure times. The composites continued to polymerize after removal of the light source. Composition of the composite resin has a major effect on the surface hardness and depth of polymerization.
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Affiliation(s)
- G Atmadja
- Department of Conservative Dentistry, University of Indonesia, Jakarta
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Liberman R, Ben-Amar A, Urstein M, Judes H. Photocure attachment lens: its effect on polymerization of visible-light-cure resin composite. Dent Mater 1990; 6:10-2. [PMID: 2376288 DOI: 10.1016/0109-5641(90)90036-e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The attachment lens for a light-curing unit which disperses light over a larger area was investigated. The effect of polymerization on a composite material was compared with that obtained with a regular light-cured tip. It was found that for similar exposure times, the efficiency of curing was significantly reduced when this lens was used.
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McCabe JF, Carrick TE. Output from visible-light activation units and depth of cure of light-activated composites. J Dent Res 1989; 68:1534-9. [PMID: 2584521 DOI: 10.1177/00220345890680111301] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A simple and reproducible method for monitoring the intensity of radiation from composite light-activation units has been developed. The method depends upon the use of a cadmium sulfide photo-conductive cell, the electrical resistance of which varies with the amount of light falling upon its surface. Filters were used for selection of the wavelength of light that is thought to be most effective in activating polymerization. The use of broad-band wavelength filters failed to give results for light intensity that correlated with depth of cure. Narrow-band interference filters, having a band width of only 10 nm and being selective within the wavelength range of from 460 to 480 nm, produced results for light intensity that correlated with depth of cure. The depths of cure for various types of composite material were measured with use of a penetrometer that enabled the thickness of unpolymerized material at the base of the test mould to be determined. The depth of cure was inversely proportional to the attenuation of light caused by the composite resin at 470 nm. The relationship between depth of cure and light intensity at 470 nm was not a simple linear one over all intensity values. Above a certain critical value of intensity (about 550 lux for a 3.5-mm aperture in these experiments), the depth of cure appeared to be almost independent of intensity. Below this critical value, depth of cure fell markedly with decreasing intensity.
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Affiliation(s)
- J F McCabe
- Dental Materials Science Unit, University of Newcastle upon Tyne, United Kingdom
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Baharav H, Abraham D, Cardash HS, Helft M. Effect of exposure time on the depth of polymerization of a visible light-cured composite resin. J Oral Rehabil 1988; 15:167-72. [PMID: 3163733 DOI: 10.1111/j.1365-2842.1988.tb00766.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effect of exposure time of a visible light source on the depth of polymerization and degree of hardness of a sample of Occlusin posterior composite resin was investigated. The border between cured and non-cured composite resin was identified by a change in colour and by applying pressure with a scalpel. Knoop hardness tests were performed perpendicular to the long axis of illumination. The composite resin nearer to the light source underwent more complete polymerization. Increased exposure time resulted in greater depth of cure. The rate of polymerization was greatest in the first 10 s. Maximum hardness measured up to a depth of 1 mm obtained after 80 s of exposure time. At greater depth, a decrease in Knoop hardness was observed. At exposures under 80 s, maximum hardness was not achieved even at a depth of only 1 mm.
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Affiliation(s)
- H Baharav
- Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel
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20
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Shue SL, Nicholls JI, Townsend JD. The effect of metal retentive designs on resin veneer retention. J Prosthet Dent 1987; 58:297-305. [PMID: 3305894 DOI: 10.1016/0022-3913(87)90044-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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DeWald JP, Ferracane JL. A comparison of four modes of evaluating depth of cure of light-activated composites. J Dent Res 1987; 66:727-30. [PMID: 3475304 DOI: 10.1177/00220345870660030401] [Citation(s) in RCA: 150] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Four commonly used methods for evaluating depth of cure in light-activated composites were compared. Optical and scraping methods correlate well, but severely overestimate depth of cure as compared with hardness testing or degree of conversion analysis. Degree of conversion appears to be the most sensitive test of depth of cure.
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Combe EC, Braden M, Brown D, Causton BE, Fletcher AM, Lloyd CH, McCabe JF, Sherriff M, Strang R, van Noort R. Dental materials: 1983 literature review. Part 2. J Dent 1986; 14:139-55. [PMID: 3531263 DOI: 10.1016/0300-5712(86)90015-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Matsumoto H, Gres JE, Marker VA, Okabe T, Ferracane JL, Harvey GA. Depth of cure of visible light-cured resin: clinical simulation. J Prosthet Dent 1986; 55:574-8. [PMID: 3458909 DOI: 10.1016/0022-3913(86)90034-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Abdalla MA, Ashrafi SH, Bapna MS, Punwani I. Degree of polymerization between adjacent visible light-cured composite areas. Dent Mater 1985; 1:188-90. [PMID: 3867575 DOI: 10.1016/s0109-5641(85)80016-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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25
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Visible light-cured composites and activating units. Council on Dental Materials, Instruments, and Equipment. J Am Dent Assoc 1985; 110:100-2. [PMID: 3855912 DOI: 10.14219/jada.archive.1985.0284] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In summary, visible light-activated composites offer better regulation of working time. Their composition differs from chemically activated composites only in the initiators and activators. The physical and mechanical properties of adequately polymerized photoactivated composites are similar to chemically activated composites. Depth of cure evaluations of the photoactivated composites are dependent on many factors, both experimental and inherent. There is currently no consensus on depth of cure values and evaluation methods. It is suggested that, if necessary, visible light-activated composites should be placed and polymerized in about 2-mm increments. It is prudent to use a longer exposure time. Exposure of visible light composites to dental operatory lights or strong ambient lighting (or both) during restorative procedures should be minimized to avoid premature polymerization. There are differences in design, spectral distribution, and radiation intensity of photoactivating light units. No definitive information is currently available on the effectiveness and optimal conditions for use of different light/composite combinations. Little information is currently available on the bioeffect of visible light radiation on human optical systems and oral tissue. At the present time there are reports of afterimages but no long-lasting bioeffects. It is strongly recommended that precautions should be taken in the care, use, and operation of photoactivating light units. Protective filter glasses should be used.
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Forsten L. Bond between subsequently added light activated composite resin and hardened material. SCANDINAVIAN JOURNAL OF DENTAL RESEARCH 1984; 92:371-3. [PMID: 6382568 DOI: 10.1111/j.1600-0722.1984.tb00904.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Because of the limited depth of cure, subsequent layers frequently have to be cured separately in connection with large fillings of light activated composite resins. This method is successful only provided that the different layers adhere to each other. Rectangular rodlike specimens of four light activated composites, two macro- and two microfilled brands, were made in three pieces cured separately (test specimens). The transverse strength of these specimens was compared with that of specimens made in one piece (controls). The strength of both test and control specimens of the macrofilled brands was the same even when water contamination was included when preparing the test specimens. In connection with the microfilled brands there was an indication of lower strength, at least after water contamination.
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