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Farah RI, Alblihed IA, Aljuoie AA, Alresheedi B. Light Polymerization through Glass-ceramics: Influence of Light-polymerizing Unit's Emitted Power and Restoration Parameters (Shade, Translucency, and Thickness) on Transmitted Radiant Power. Contemp Clin Dent 2024; 15:35-43. [PMID: 38707663 PMCID: PMC11068246 DOI: 10.4103/ccd.ccd_124_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 01/30/2024] [Accepted: 02/08/2024] [Indexed: 05/07/2024] Open
Abstract
Background This in vitro study assessed light transmission through ceramic discs varying in shade, translucency, and thickness using light-polymerizing units with different radiant power/flux (RP) outputs. Methods Disc-shaped specimens (0.5 mm, 1.0 mm, and 2.0 mm) were made from high and low-translucency glass-ceramic ingots (IPS e.max Press) in shades A1 and A4, totaling 60 discs. Two light-polymerizing units with different power outputs were used, and their emission spectra were verified. The transmitted RP values for each ceramic specimen were measured and irradiance and radiant energy influx were calculated. Differences between the light-polymerizing units and the influence of the three ceramic parameters were evaluated using an independent-samples t-test and three-way analysis of variance (ANOVA) tests (α = 0.05). Results A statistically significant difference was observed in the mean transmitted RP values between the two light-polymerizing units. Furthermore, the three-way ANOVA test showed a significant effect of shade, translucency, and thickness, as well as a significant interaction between each pair of variables and all three variables on the transmitted RP (P < 0.05). Conclusions Despite the significant attenuation in the transmitted RP, especially in ceramics with higher shade chromaticity and thickness and lower translucency, the calculated minimal irradiance values for both light-polymerizing units (their emitted power ≥ 500 mW) were greater than the minimum recommended irradiance threshold (100 mW/cm2). However, the exposure duration needs to be increased to provide the resin with sufficient radiant exposure for adequate polymerization.
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Affiliation(s)
- Ra’fat I. Farah
- Department of Prosthetic Dental Sciences, College of Dentistry, Qassim University, Al-Mulaydah, Qassim, Saudi Arabia
| | - Ibrahim A. Alblihed
- Medical City, College of Dentistry, Qassim University, Al-Mulaydah, Qassim, Saudi Arabia
| | - Alhareth A. Aljuoie
- Medical City, College of Dentistry, Qassim University, Al-Mulaydah, Qassim, Saudi Arabia
| | - Bandar Alresheedi
- Department of Prosthetic Dental Sciences, College of Dentistry, Qassim University, Al-Mulaydah, Qassim, Saudi Arabia
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Ortiz-Magdaleno M, Bogarin-Topete ER, Cerda-Cristerna BI, Gutiérrez-Sánchez M. Effect of degree of conversion on the surface properties of polymerized resin cements used for luting glass fiber posts. J Prosthet Dent 2023; 130:256.e1-256.e12. [PMID: 37357085 DOI: 10.1016/j.prosdent.2023.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/12/2023] [Accepted: 05/16/2023] [Indexed: 06/27/2023]
Abstract
STATEMENT OF PROBLEM Lack of conversion of resin cements for luting glass fiber posts in deeper levels of the root canal may compromise clinical performance. PURPOSE The purpose of this in vitro study was to evaluate the effect of the degree of conversion on the surface properties of dual-polymerized resin cements used for cemented glass fiber posts according to the root level. MATERIAL AND METHODS Fifty maxillary central incisor teeth were endodontically treated, and glass fiber posts were cemented using the following systems: self-adhesive dual-polymerized resin luting cement (RelyX U200) and dual-polymerizing flowable core and a post luting system (Rebilda DC) with a self-etching adhesive (Futurabond DC). The degree of conversion was determined via attenuated total reflectance and Fourier transform infrared spectroscopy, and surface microhardness and cement film thickness were measured. The intraradicular fit was evaluated with microscopy. All tests were performed in the coronal, middle, and apical third of the root canal. Statistical analysis was done with ANOVA and the multiple comparison Tukey test (α=.05). RESULTS The degree of conversion was higher in the coronal third using Rebilda DC (65.3 ±4.8%) than RelyX U200 (38.7 ±5.3%) (P<.05); on both resin cements, these values decreased from the coronal to the apical third (30.9 ±3.7%, 61.9 ±8.7%, respectively). The cement film thickness was higher for RelyX U200 in the 3 thirds than for Rebilda DC; significant differences (P<.05) were recorded in both cementing systems in the coronal and apical thirds. In the middle third, no significant differences were observed (P>.05). The mean surface microhardness values increased in the coronal thirds and decreased with increasing root canal depth. The marginal seal in the coronal thirds and the intraradicular fit in the middle thirds showed closer adaptation; however, some tags were observed in the interface resin cement and radicular dentin. Gap and tag formations were observed in the apical third. CONCLUSIONS Depending on the root canal third, the surface properties of dual-polymerized resin cements are influenced by the degree of conversion.
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Affiliation(s)
- Marine Ortiz-Magdaleno
- Professor, Graduate Prosthodontics, Specialty in Aesthetic, Cosmetic, Restorative, and Implant Dentistry, Faculty of Stomatology, Autonomous University of San Luis Potosi, San Luis Potosi, Mexico.
| | - Edson R Bogarin-Topete
- Graduate student, Graduate Prosthodontics, Specialty in Aesthetic, Cosmetic, Restorative, and Implant Dentistry, Faculty of Stomatology, Autonomous University of San Luis Potosi, San Luis Potosi, Mexico
| | | | - Mariana Gutiérrez-Sánchez
- Professor, Endodontics Postgraduate Program, Faculty of Stomatology, Autonomous University of San Luis Potosí, San Luis Potosi, Mexico
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Lempel E, Szebeni D, Őri Z, Kiss T, Szalma J, Lovász BV, Kunsági-Máté S, Böddi K. The effect of high-irradiance rapid polymerization on degree of conversion, monomer elution, polymerization shrinkage and porosity of bulk-fill resin composites. Dent Mater 2023; 39:442-453. [PMID: 36918332 DOI: 10.1016/j.dental.2023.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/17/2023] [Accepted: 03/03/2023] [Indexed: 03/13/2023]
Abstract
OBJECTIVE The purpose was to compare the degree of conversion (DC), monomer elution (ME), polymerization shrinkage (PS) and porosity of two addition-fragmentation chain transfer (AFCT) modified resin-based composites (RBC) light-cured with rapid- (RP), turbo- (TP) or conventional polymerization (CP) settings. METHODS Cylindrical samples (6-mm wide, 4-mm thick) were prepared from Tetric PowerFill (TPF) and Filtek One Bulk (FOB). Four groups were established according to the polymerization settings: 3s-RP, 5s-TP, 10s-CP and 20s-CP. Samples in 1 mm thickness with 20s-CP settings served as controls. The DC at the top and bottom surfaces was measured with micro-Raman spectroscopy. ME was detected with high-performance liquid chromatography. PS and porosity were analyzed by micro-computed tomography. ANOVA and Tukey's post-hoc test, multivariate analysis and partial eta-squared statistics were used to analyze the data (p < 0.05). RESULTS FOB showed higher DC values (61.5-77.5 %) at the top compared to TPF (43.5-67.8 %). At the bottom TPF samples achieved higher DCs (39.9-58.5 %) than FOB (18.21-66.18 %). Extending the curing time increased DC (except the top of FOB) and decreased ME. BisGMA release was the highest among the detected monomers from both RBCs. The amount was three-fold more from TPF. The factor Material and Exposure significantly influenced DC and ME. PS (1.8-2.5 %) did not differ among the groups and RBCs except for the lowest value of TPF cured with the 3s_RP setting (p = 0.03). FOB showed 4.5-fold lower porosity (p < 0.001). Significantly higher pore volume was detected after polymerization in 3s_RP (p < 0.001). SIGNIFICANCE High-irradiance rapid 3-s curing of AFCT modified RBCs resulted in inferior results for some important material properties. A longer exposure time is recommended in a clinical situation.
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Affiliation(s)
- Edina Lempel
- Department of Restorative Dentistry and Periodontology, University of Pécs Medical School, Tüzér Street 1, Pécs 7623, Hungary.
| | - Donát Szebeni
- Department of Restorative Dentistry and Periodontology, University of Pécs Medical School, Tüzér Street 1, Pécs 7623, Hungary
| | - Zsuzsanna Őri
- János Szentágothai Research Center, Ifjúság Street 12, Pécs 7624, Hungary; Department of General and Physical Chemistry, University of Pécs, Ifjúság Street 6, Pécs 7624, Hungary
| | - Tamás Kiss
- János Szentágothai Research Center, Ifjúság Street 12, Pécs 7624, Hungary
| | - József Szalma
- Department of Oral and Maxillofacial Surgery, University of Pécs Medical School, Tüzér Street 1, Pécs 7623, Hungary
| | - Bálint Viktor Lovász
- Department of Oral and Maxillofacial Surgery, University of Pécs Medical School, Tüzér Street 1, Pécs 7623, Hungary
| | - Sándor Kunsági-Máté
- János Szentágothai Research Center, Ifjúság Street 12, Pécs 7624, Hungary; Department of Organic and Medicinal Chemistry, University of Pécs, Faculty of Pharmacy, Honvéd Street 1, Pécs 7624, Hungary
| | - Katalin Böddi
- Department of Biochemistry and Medical Chemistry, University of Pécs Medical School, Szigeti Street 12, Pécs 7624, Hungary
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Watts DC. Light-curing dental resin-based composites: How it works and how you can make it work. FRONTIERS IN DENTAL MEDICINE 2023. [DOI: 10.3389/fdmed.2023.1108316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
AimClinicians may become quite familiar with the rapid transformation of composite pastes to rigid solids, as a routine phenomenon in operative dentistry. But they may still lack scientific understanding of how and why this happens. Efforts to learn scientifically about the interaction between light beams and resin-composites can significantly promote effective clinical placement of restorations. Neglect of such study can result in practical procedures of light-curing that are inadequate or even seriously defective.MethodThis review addresses the underlying science and technology to elucidate how light curing works, for dental resin-based composites, including—but not limited to—bulk fill types. This involves questions concerning: (a) the particle-wave understanding of light; (b) how photons can penetrate sufficiently deeply into bulk fill composites; (c) the necessary technology of LED light-curing units (LCUs); (d) the criteria for absorption of photons by photo initiators to initiate free-radical addition polymerisation.ConclusionsThe implications for clinical practice are surveyed. These include design variables and selection criteria for LED-LCUs and guidelines on their use. This is to guide practitioners towards safe and effective light-curing procedures so that they can achieve optimal result for their patients.
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Maucoski C, Price RB, Rocha MG, Roulet JF, Sullivan B. Ability of short exposures from laser and quad-wave curing lights to photo-cure bulk-fill resin-based composites. Dent Mater 2023; 39:275-292. [PMID: 36868892 DOI: 10.1016/j.dental.2023.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/10/2023] [Accepted: 01/25/2023] [Indexed: 03/05/2023]
Abstract
OBJECTIVE This study investigated the ability of a laser, and a 'quad-wave' LCU, to photo-cure paste and flowable bulk-fill resin-based composites (RBCs). METHODS Five LCUs and nine exposure conditions were used. The laser LCU (Monet) used for 1 s and 3 s, the quad-wave LCU (PinkWave) used for 3 s in the Boost and 20 s in the Standard modes, the the multi-peak LCU (Valo X) used for 5 s in the Xtra and 20 s in the Standard modes, were compared to the polywave PowerCure used in the 3 s mode and for 20 s in the Standard mode, and to the mono-peak SmartLite Pro used for 20 s. Two paste consistency bulk-fill RBCs: Filtek One Bulk Fill Shade A2 (3 M), Tetric PowerFill Shade IVA (Ivoclar Vivadent), and two flowable RBCs: Filtek Bulk Fill Flowable Shade A2 (3 M), Tetric PowerFlow Shade IVA (Ivoclar Vivadent) were photo-cured in 4-mm deep x 4-mm diameter metal molds. The light received by these specimens was measured using a spectrometer (Flame-T, Ocean Insight), and the radiant exposure delivered to the top surface of the RBCs was mapped. The immediate degree of conversion (DC) at the bottom, and the 24-hour Vickers Hardness (VH) at the top and bottom of the RBCs were measured and compared. RESULTS The irradiance received by the 4-mm diameter specimens ranged from 1035 mW/cm2 (SmartLite Pro) to 5303 mW/cm2 (Monet). The radiant exposures between 350 and 500 nm delivered to the top surface of the RBCs ranged from 5.3 J/cm2 (Monet in 1 s) to 26.4 J/cm2 (Valo X), although the PinkWave delivered 32.1 J/cm2 in 20 s 350 to 900 nm. All four RBCs achieved their maximum DC and VH values at the bottom when photo-cured for 20 s. The Monet used for 1 s and the PinkWave used for 3 s on the Boost setting delivered the lowest radiant exposures between 420 and 500 nm (5.3 J/cm2 and 3.5 J/cm2 respectively), and they produced the lowest DC and VH values. CONCLUSIONS Despite delivering a high irradiance, the short 1 or 3-s exposures delivered less energy to the RBC than 20-s exposures from LCUs that deliver> 1000 mW/cm2. There was an excellent linear correlation (r > 0.98) between the DC and the VH at the bottom. There was a logarithmic relationship between the DC and the radiant exposure (Pearson's r = 0.87-97) and between the VH and the radiant exposure (Pearson's r = 0.92-0.96) delivered in the 420-500 nm range.
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Affiliation(s)
- Cristiane Maucoski
- Department of Restorative Dentistry, State University of Ponta Grossa, Ponta Grossa, Parana, Brazil; Department of Dental Clinical Sciences, Dalhousie University, Faculty of Dentistry, Halifax, Nova Scotia, Canada
| | - Richard Bengt Price
- Department of Dental Clinical Sciences, Dalhousie University, Faculty of Dentistry, Halifax, Nova Scotia, Canada.
| | - Mateus Garcia Rocha
- Department of Restorative Dental Science, Center of Dental Biomaterials College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Jean-François Roulet
- Department of Restorative Dental Science, Center of Dental Biomaterials College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Braden Sullivan
- Department of Restorative Dentistry, State University of Ponta Grossa, Ponta Grossa, Parana, Brazil
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Time-dose reciprocity mechanism for the inactivation of Escherichia coli explained by a stochastic process with two inactivation effects. Sci Rep 2022; 12:22588. [PMID: 36585428 PMCID: PMC9801147 DOI: 10.1038/s41598-022-26783-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 12/20/2022] [Indexed: 12/31/2022] Open
Abstract
There is a great demand for developing and demonstrating novel disinfection technologies for protection against various pathogenic viruses and bacteria. In this context, ultraviolet (UV) irradiation offers an effective and convenient method for the inactivation of pathogenic microorganisms. The quantitative evaluation of the efficacy of UV sterilization relies on the simple time-dose reciprocity law proposed by Bunsen-Roscoe. However, the inactivation rate constants reported in the literature vary widely, even at the same dose and wavelength of irradiation. Thus, it is likely that the physical mechanism of UV inactivation cannot be described by the simple time-dose reciprocity law but requires a secondary inactivation process, which must be identified to clarify the scientific basis. In this paper, we conducted a UV inactivation experiment with Escherichia coli at the same dose but with different irradiances and irradiation durations, varying the irradiance by two to three orders of magnitude. We showed that the efficacy of inactivation obtained by UV-light emitting diode irradiation differs significantly by one order of magnitude at the same dose but different irradiances at a fixed wavelength. To explain this, we constructed a stochastic model introducing a second inactivation rate, such as that due to reactive oxygen species (ROS) that contribute to DNA and/or protein damage, together with the fluence-based UV inactivation rate. By solving the differential equations based on this model, the efficacy of inactivation as a function of the irradiance and irradiation duration under the same UV dose conditions was clearly elucidated. The proposed model clearly shows that at least two inactivation rates are involved in UV inactivation, where the generally used UV inactivation rate does not depend on the irradiance, but the inactivation rate due to ROS does depend on the irradiance. We conclude that the UV inactivation results obtained to date were simply fitted by one inactivation rate that superimposed these two inactivation rates. The effectiveness of long-term UV irradiation at a low irradiance but the same dose provides useful information for future disinfection technologies such as the disinfection of large spaces, for example, hospital rooms using UV light, because it can reduce the radiation dose and its risk to the human body.
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Smith KA, Habibi S, de Beer MP, Pritchard ZD, Burns MA. Dual-wavelength volumetric stereolithography of multilevel microfluidic devices. BIOMICROFLUIDICS 2022; 16:044106. [PMID: 35935121 PMCID: PMC9352368 DOI: 10.1063/5.0094721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Microfluidic devices are typically fabricated in an expensive, multistep process (e.g., photolithography, etching, and bonding). Additive manufacturing (AM) has emerged as a revolutionary technology for simple and inexpensive fabrication of monolithic structures-enabling microfluidic designs that are challenging, if not impossible, to make with existing fabrication techniques. Here, we introduce volumetric stereolithography (vSLA), an AM method in which polymerization is constrained to specific heights within a resin vat, allowing layer-by-layer fabrication without a moving platform. vSLA uses an existing dual-wavelength chemistry that polymerizes under blue light (λ = 458 nm) and inhibits polymerization under UV light (λ = 365 nm). We apply vSLA to fabricate microfluidic channels with different spatial and vertical geometries in less than 10 min. Channel heights ranged from 400 μm to 1 mm and could be controlled with an optical dose, which is a function of blue and UV light intensities and exposure time. Oxygen in the resin was found to significantly increase the amount of dose required for curing (i.e., polymerization to a gelled state), and we recommend that an inert vSLA system is used for rapid and reproducible microfluidic fabrication. Furthermore, we recommend polymerizing far beyond the gel point to form more rigid structures that are less susceptible to damage during post-processing, which can be done by simultaneously increasing the blue and UV light absorbance of the resin with light intensities. We believe that vSLA can simplify the fabrication of complex multilevel microfluidic devices, extending microfluidic innovation and availability to a broader community.
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Affiliation(s)
- Kaylee A. Smith
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Sanaz Habibi
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | - Zachary D. Pritchard
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Mark A. Burns
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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Rackson CM, Champley KM, Toombs JT, Fong EJ, Bansal V, Taylor HK, Shusteff M, McLeod RR. Object-Space Optimization of Tomographic Reconstructions for Additive Manufacturing. ADDITIVE MANUFACTURING 2021; 48:102367. [PMID: 34900610 PMCID: PMC8656269 DOI: 10.1016/j.addma.2021.102367] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Volumetric 3D printing motivated by computed axial lithography enables rapid printing of homogeneous parts but requires a high dimensionality gradient-descent optimization to calculate image sets. Here we introduce a new, simpler approach to image-computation that algebraically optimizes a model of the printed object, significantly improving print accuracy of complex parts under imperfect material and optical precision by improving optical dose contrast between the target and surrounding regions. Quality metrics for volumetric printing are defined and shown to be significantly improved by the new algorithm. The approach is extended beyond binary printing to grayscale control of conversion to enable functionally graded materials. The flexibility of the technique is digitally demonstrated with realistic projector point spread functions, printing around occluding structures, printing with restricted angular range, and incorporation of materials chemistry such as inhibition. Finally, simulations show that the method facilitates new printing modalities such as printing into flat, rather than cylindrical packages to extend the applications of volumetric printing.
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Affiliation(s)
- Charles M. Rackson
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309, USA
| | - Kyle M. Champley
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Joseph T. Toombs
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Erika J. Fong
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Vishal Bansal
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Hayden K. Taylor
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Maxim Shusteff
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Robert R. McLeod
- Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO 80309, USA
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Sullivan B, Kalliecharan D, Kostylev I, Earle G, Stansbury JW, Price RB, Labrie D. Photo-polymerization kinetics of a dental resin at a high temporal resolution. J Mech Behav Biomed Mater 2021; 124:104884. [PMID: 34638087 DOI: 10.1016/j.jmbbm.2021.104884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVES This study: 1) aims to measure with high temporal resolution the intrinsic rate of the degree of conversion (DC) of a dental resin-based composite (RBC) photo-cured at two irradiances; 2) aims to determine the transition time at which the DC rate is maximum; 3) used two different irradiances to measure the shift in transition time; 4) aims to compare transition times measured using DC and shrinkage strain. METHODS Samples (n = 20) 1 mm thick by 10 mm diameter of Filtek One bulk-fill restorative A2 shade (3M Oral Care) were photocured for 20 s with a single emission peak (wavelength centered at 455 nm) light-emitting-diode-based light-curing unit at irradiance levels of 890 mW/cm2 and 209 mW/cm2, and initial sample temperature of T = 23 °C. The DC was measured in real-time using Attenuated Total Reflection (ATR) FTIR spectroscopy with a sampling rate of 13 DC data points per second. The data were analyzed within a phenomenological autocatalytic model. In addition, the axial shrinkage strain was measured using 3 samples of the RBC with the same outer dimensions and under similar experimental conditions using the bonded disk method and an interferometric technique. RESULTS For the 890 mW/cm2 and 209 mW/cm2 irradiance levels, the DC with time was found to agree with the model enabling the determination of transition times of 0.66 ± 0.05 s and 2.3 ± 0.2 s, and the DC at these times of 5.5 ± 0.2% and 6.4 ± 0.2%. The maximum linear strain rate at 0.76 ± 0.01 s and 1.98 ± 0.02 s for the 890 mW/cm2 and 209 mW/cm2 irradiance levels, respectively, are within two standard deviations of the corresponding transition times. SIGNIFICANCE At an irradiance level much greater than 1000 mW/cm2, the photo-polymerization kinetics of a dental RBC may be too fast to be measured accurately using ATR-FTIR spectroscopy. A viable alternative to monitor the kinetics is through the measurements of the axial shrinkage strain employing the bonded disk method and an interferometric technique.
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Affiliation(s)
- Braden Sullivan
- Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - David Kalliecharan
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Ivan Kostylev
- Quantum Dynamics Unit, Okinawa Institute of Science and Technology, Tancha 1919-1, Okinawa, 904-0495, Japan
| | - Guy Earle
- IObIO Inc., 1676 Edward Street, Halifax, Nova Scotia, B3H 3J3, Canada
| | - Jeffrey W Stansbury
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, 80045, United States; Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80309-0596, United States
| | - Richard B Price
- Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Daniel Labrie
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
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Tichy A, Bradna P. Applicability of Exposure Reciprocity Law for Fast Polymerization of Restorative Composites Containing Various Photoinitiating Systems. Oper Dent 2021; 46:406-418. [PMID: 34478559 DOI: 10.2341/20-112-l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2020] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The exposure reciprocity law (ERL) has been used to calculate the optimal irradiation time of dental composites. This study examined the applicability of ERL for fast polymerization of restorative composites containing various photoinitiating systems using a high-power multi-peak light-emitting diode (LED) lamp. METHODS Three commercial composites differing in photoinitiating systems were tested: Filtek Ultimate Universal Restorative (FU) with a camphorquinone-amine (CQ-A) photoinitiating system, Tetric EvoCeram (TEC) with CQ-A and (2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and Estelite Σ Quick (ESQ) with CQ and a radical amplified photopolymerization (RAP) initiator. Specimens 2-mm thick were polymerized using a high-power multipeak LED lamp (Valo) at 3 pairs of radiant exposures (referred to as low, moderate, and high) ranging from 15.8-26.7 J/cm2. They were achieved by different combinations of irradiation time (5-20 seconds) and irradiance (1300-2980 mW/cm2) as determined with a calibrated spectrometer. Knoop microhardness was measured 1, 24, and 168 hours after polymerization on specimen top (irradiated) and bottom surfaces to characterize the degree of polymerization. The results were statistically analyzed using a three-way analysis of variance and Tukey's post hoc tests, α = 0.05. RESULTS Microhardness increased with radiant exposure and except for ESQ, top-surface microhardness was significantly higher than that on bottom surfaces. Combinations of high irradiance and short irradiation time significantly increased the top-surface microhardness of TEC at low and moderate radiant exposures, and the bottom-surface microhardness of FU at a low radiant exposure. In contrast, the microhardness of ESQ on both surfaces at high radiant exposure increased significantly when low irradiance and long irradiation time were used. With all tested composites, bottom-surface microhardness obtained at low radiant exposure was below 80% of the maximum top-surface microhardness, indicating insufficient polymerization. CONCLUSION Combinations of irradiance and irradiation time had a significant effect on microhardness, which was affected by photoinitiators and the optical properties of composites as well as spectral characteristics of the polymerization lamp. Therefore, ERL cannot be universally applied for the calculation of optimal composite irradiation time. Despite high irradiance, fast polymerization led to insufficient bottom-surface microhardness, suggesting the necessity to also characterize the degree of polymerization on the bottom surfaces of composite increments when assessing the validity of ERL.
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de Kuijper MCFM, Ong Y, Gerritsen T, Cune MS, Gresnigt MMM. Influence of the ceramic translucency on the relative degree of conversion of a direct composite and dual-curing resin cement through lithium disilicate onlays and endocrowns. J Mech Behav Biomed Mater 2021; 122:104662. [PMID: 34246079 DOI: 10.1016/j.jmbbm.2021.104662] [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] [Received: 03/31/2021] [Revised: 06/21/2021] [Accepted: 06/25/2021] [Indexed: 10/21/2022]
Abstract
INTRODUCTION The goal of this study was to investigate the influence of the ceramic translucency, restoration type and polymerization time on the relative degree of conversion of a dual-curing resin cement and a conventional microhybrid resin composite using a high-power light-curing device. METHODS AND MATERIALS Two 4.0 mm thick onlay (O) and two 7.5 mm thick endocrown (E) lithium disilicate restorations in high and low translucency (HT/LT) were fabricated on a decapitated molar. The pulp chamber was prepared to accommodate a 2 mm layer of a microhybrid resin composite (MHC) or dual-curing resin cement (DCC). Composite specimens were light-cured (n = 15; 1200 mW/cm2) without or through an onlay or endocrown restoration. Fourier-transform infrared spectroscopy (FTIR) absorbance curves were collected for the same composite specimen after 3 × 20, 3 × 40, 3 × 60 and 3 × 90 s of light-curing. The relative degree of conversion (DC%) was calculated and results analyzed using Kruskal-Wallis test and Friedman's ANOVA. Alpha was set at 0.05. RESULTS After 3 × 60 s, the DC of MHC was significantly lower (p = 0.03; r = 0.61) under LT/EC restorations (Mdn: 77.8%) than HT/EC restorations (Mdn: 95.2%). DC of the DCC was not significantly affected by the ceramic translucency or restoration type. MHC had a significant higher DC than DCC under the HT/O, LT/O and HT/E restorations. There were no significant differences between MHC and DCC cured through LT/E restorations. CONCLUSION DC for DCC was not significantly affected by the ceramic translucency or restoration type. DC for MHC was significantly lower for LT/EC than HT/EC restorations after 3 × 60s polymerization, but not different for the high translucent restorations and low translucent onlays. CLINICAL RELEVANCE the use of light-curing microhybrid composite for bonding high translucent onlays and endocrowns and low translucent onlays seems feasible.
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Affiliation(s)
- Maurits C F M de Kuijper
- The University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Department of Restorative Dentistry and Biomaterials, Groningen, the Netherlands; Martini Hospital, Department of Special Dental Care, Groningen, the Netherlands.
| | - Yori Ong
- The University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Department of Restorative Dentistry and Biomaterials, Groningen, the Netherlands
| | - Tobias Gerritsen
- The University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Department of Restorative Dentistry and Biomaterials, Groningen, the Netherlands
| | - Marco S Cune
- The University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Department of Restorative Dentistry and Biomaterials, Groningen, the Netherlands; St. Antonius Hospital Nieuwegein, Department of Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care, Nieuwegein, the Netherlands; University Medical Center Utrecht, Department of Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care, Utrecht, the Netherlands
| | - Marco M M Gresnigt
- The University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Department of Restorative Dentistry and Biomaterials, Groningen, the Netherlands; Martini Hospital, Department of Special Dental Care, Groningen, the Netherlands
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12
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Uzcategui AC, Higgins CI, Hergert JE, Tomaschke AE, Crespo-Cuevas V, Ferguson VL, Bryant SJ, McLeod RR, Killgore JP. Microscale Photopatterning of Through-thickness Modulus in a Monolithic and Functionally Graded 3D Printed Part. SMALL SCIENCE 2021; 1:2000017. [PMID: 34458889 PMCID: PMC8388578 DOI: 10.1002/smsc.202000017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
3D printing is transforming traditional processing methods for applications ranging from tissue engineering to optics. To fulfill its maximum potential, 3D printing requires a robust technique for producing structures with precise three-dimensional (x, y and z) control of mechanical properties. Previous efforts to realize such spatial control of modulus within 3D printed parts have largely focused on low-resolution (mm to cm scale) multi-material processes and grayscale approaches that spatially vary the modulus in the x-y plane and energy dose-based (E = I 0 t exp) models that do not account for the resin's sub-linear response to irradiation intensity. Here, we demonstrate a novel approach for through-thickness (z) voxelated control of mechanical properties within a single-material, monolithic part. Control over the local modulus is enabled by a predictive model that incorporates the observed non-reciprocal dose response of the material. The model is validated by an application of atomic force microscopy to map the through-thickness modulus on multi-layered 3D parts. Overall, both smooth gradations (30 MPa change over ≈75 μm) and sharp step-changes (30 MPa change over ≈5 μm) in modulus are realized in poly(ethylene glycol) diacrylate based 3D constructs, paving the way for advancements in tissue engineering, stimuli-responsive 4D printing and graded metamaterials.
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Affiliation(s)
- Asais Camila Uzcategui
- Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Callie I. Higgins
- Applied Chemicals and Materials Division (647), National Institute of Standards and Technology (NIST), Boulder, CO 80305
| | - John E. Hergert
- Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Andrew E. Tomaschke
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA
| | - Victor Crespo-Cuevas
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA
| | - Virginia L. Ferguson
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Stephanie J. Bryant
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Robert R. McLeod
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Boulder, CO 80309, USA; Materials Science and Engineering, University of Colorado, Boulder, USA, Boulder, CO 80309, USA
| | - Jason P. Killgore
- Applied Chemicals and Materials Division (647), National Institute of Standards and Technology (NIST), Boulder, CO 80305
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13
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Bin Nooh AN, Nahedh HA, AlRefeai M, Alkhudhairy F. The Effect of Irradiance on the Degree of Conversion and Volumetric Polymerization Shrinkage of Different Bulk-Fill Resin-Based Composites: An In Vitro Study. Eur J Dent 2020; 15:312-319. [PMID: 33321544 PMCID: PMC8184305 DOI: 10.1055/s-0040-1721236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Objective
The influence of different light-emitting diode (LED) curing light intensities on the degree of conversion (DC) and volumetric polymerization shrinkage (VPS) of bulk-fill resin-based composite (RBC) restorative materials was evaluated.
Materials and Methods
Twenty-four specimens of each RBC material (Filtek one bulk-fill posterior, Reveal HD Bulk, Tetric N-Ceram, and Filtek Z350) were prepared. The RBCs were shaped in molds and cured using an LED curing light unit at high-intensity (1,200 mW/cm
2
) for 20 seconds and low-intensity (650 mW/cm
2
) for 40 seconds Fourier-transform infrared (FTIR) spectroscopy was used to determine the DC and microcomputed tomography was used to evaluate VPS. Data were analyzed using one- and two-way ANOVA, independent
t
-test, and Tukey’s and Scheffe’s post hoc multiple comparison tests.
Results
With high-intensity curing light, Reveal HD showed the highest DC (85.689 ± 6.811%) and Tetric N-Ceram the lowest (52.60 ± 9.38%). There was no statistical difference in VPS when using high- or low-intensity curing light. The highest VPS was observed for Reveal HD (2.834–3.193%); there was no statistical difference (
p
> 0.05) among the other RBCs.
Conclusion
Curing light intensities do not significantly influence the VPS of RBC materials. Reveal HD bulk cured with high-intensity light had the highest DC.
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Affiliation(s)
- Abrar N Bin Nooh
- Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Hend Al Nahedh
- Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Mohammad AlRefeai
- Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Fahad Alkhudhairy
- Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia
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14
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Czech Z, Kabatc J, Bartkowiak M, Licbarski A, Mozelewska K, Kwiatkowska D. Novel Photoreactive Pressure-Sensitive Adhesives (PSA) Based on Acrylics Containing Additionable Photoinitiators. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E5151. [PMID: 33207630 PMCID: PMC7697178 DOI: 10.3390/ma13225151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/07/2020] [Accepted: 11/10/2020] [Indexed: 11/16/2022]
Abstract
A new class of additionable ultraviolet photoinitiators that can be used, through addition, for modification of the acrylic polymer chain and their influence of main properties of acrylic pressure-sensitive adhesives (PSAs) is described here. The photoinitiators studied are based on benzophenone, dibenzofuran and anthraquinone chromophores. The propyleneimine carbonyl is the reactive additionable group incorporated in the photoinitiator structure. First, the solvent-borne acrylic pressure-sensitive adhesive was synthesized and characterized. Then, a photoinitiator suitable for addition to the acrylic polymer chain possessing a carboxyl group was added before UV-irradiation. A mechanism of UV-initiated cross-linking reaction of acrylic PSA with additionable photoinitiators was done as well. The influence of the concentration and type of photoinitiator, UV-crosslinking time and UV-dose on peel adhesion, shear strength and tack of solvent-borne acrylic pressure-sensitive adhesives cross-linked by UV light was studied and presented here. It was found that the tack depends on the UV-dose and photoinitiator concentration. An increase of UV dose results in an increase of shear strength of acrylic pressure-sensitive adhesive (PSA) formulations.
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Affiliation(s)
- Zbigniew Czech
- International Laboratory of Adhesives and Self-Adhesive Materials, Department of Chemical Organic Technology and Polymeric Materials, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego 10, 70-322 Szczecin, Poland; (M.B.); (A.L.); (K.M.)
| | - Janina Kabatc
- Department of Organic Chemistry, Faculty of Chemical Technology and Engineering, UTP University of Science and Technology, Seminaryjna 3, 85-326 Bydgoszcz, Poland;
| | - Marcin Bartkowiak
- International Laboratory of Adhesives and Self-Adhesive Materials, Department of Chemical Organic Technology and Polymeric Materials, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego 10, 70-322 Szczecin, Poland; (M.B.); (A.L.); (K.M.)
| | - Adam Licbarski
- International Laboratory of Adhesives and Self-Adhesive Materials, Department of Chemical Organic Technology and Polymeric Materials, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego 10, 70-322 Szczecin, Poland; (M.B.); (A.L.); (K.M.)
| | - Karolina Mozelewska
- International Laboratory of Adhesives and Self-Adhesive Materials, Department of Chemical Organic Technology and Polymeric Materials, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego 10, 70-322 Szczecin, Poland; (M.B.); (A.L.); (K.M.)
| | - Dominika Kwiatkowska
- Department of Organic Chemistry, Faculty of Chemical Technology and Engineering, UTP University of Science and Technology, Seminaryjna 3, 85-326 Bydgoszcz, Poland;
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15
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A standardized method to determine the effect of polymerization shrinkage on the cusp deflection and shrinkage induced built-in stress of class II tooth models. J Mech Behav Biomed Mater 2020; 111:103987. [DOI: 10.1016/j.jmbbm.2020.103987] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 06/21/2020] [Accepted: 07/10/2020] [Indexed: 11/19/2022]
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16
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Cook CC, Fong EJ, Schwartz JJ, Porcincula DH, Kaczmarek AC, Oakdale JS, Moran BD, Champley KM, Rackson CM, Muralidharan A, McLeod RR, Shusteff M. Highly Tunable Thiol-Ene Photoresins for Volumetric Additive Manufacturing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003376. [PMID: 33002275 DOI: 10.1002/adma.202003376] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 07/20/2020] [Indexed: 05/17/2023]
Abstract
Volumetric additive manufacturing (VAM) forms complete 3D objects in a single photocuring operation without layering defects, enabling 3D printed polymer parts with mechanical properties similar to their bulk material counterparts. This study presents the first report of VAM-printed thiol-ene resins. With well-ordered molecular networks, thiol-ene chemistry accesses polymer materials with a wide range of mechanical properties, moving VAM beyond the limitations of commonly used acrylate formulations. Since free-radical thiol-ene polymerization is not inhibited by oxygen, the nonlinear threshold response required in VAM is introduced by incorporating 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a radical scavenger. Tuning of the reaction kinetics is accomplished by balancing inhibitor and initiator content. Coupling this with quantitative measurements of the absorbed volumetric optical dose allows control of polymer conversion and gelation during printing. Importantly, this work thereby establishes the first comprehensive framework for spatial-temporal control over volumetric energy distribution, demonstrating structures 3D printed in thiol-ene resin by means of tomographic volumetric VAM. Mechanical characterization of this thiol-ene system, with varied ratios of isocyanurate and triethylene glycol monomers, reveals highly tunable mechanical response far more versatile than identical acrylate-based resins. This broadens the range of materials and properties available for VAM, taking another step toward high-performance printed polymers.
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Affiliation(s)
- Caitlyn C Cook
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Erika J Fong
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | | | | | | | - James S Oakdale
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Bryan D Moran
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Kyle M Champley
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Charles M Rackson
- Electrical, Computer, and Energy Engineering Department, University of Colorado, Boulder, CO, 80309, USA
| | - Archish Muralidharan
- Materials Science and Engineering Program, University of Colorado, Boulder, CO, 80303, USA
| | - Robert R McLeod
- Electrical, Computer, and Energy Engineering Department, University of Colorado, Boulder, CO, 80309, USA
| | - Maxim Shusteff
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
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17
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Watts DC, Algamaiah H. Characterizing surface viscoelastic integrity of ultra-fast photo-polymerized composites: Methods development. Dent Mater 2020; 36:1255-1265. [PMID: 32819731 DOI: 10.1016/j.dental.2020.07.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Resin-Composites are now available designed for polymerization using 3 s of intense light irradiation. The aim was to develop an experimental method to probe their surface viscoelastic integrity immediately following such rapid photo-cure via macroscopic surface indentation under constant stress as a function of time. METHODS Two bulk-fill composites (Ivoclar AG) were studied: Tetric PowerFill (PFill) and PowerFlow (PFlow). Split molds were used to fabricate cylindrical {4 mm (dia) × 4 mm} paste specimens, irradiated at 23 °C at 0 mm from the top surface with a BluephasePowerCure LED-LCU, with 3 s or 5 s modes, emitting 3 and 2 W/cm2, respectively. Post-irradiation specimens were immediately transferred to an apparatus equipped with a flat-ended indentor of 1.5 mm diameter. 14 MPa compressive stress at the indentor tip was applied centrally in < 2 min and maintained constant for 2 h. Indentation (I) magnitudes were recorded in real-time (t), with I(t) data re-expressed as % indentation relative to the 4 mm specimen height. After 2 h, the indentor was unloaded and indentation recovery was monitored for a further 2 h. Parallel sets of measurements were made where indentation was delayed for 24 h. Further measurements were made with more conventional composites: EvoCeram Bulk Fill (ECeram) and Tetric EvoFlow Bulk Fill (EFlow). These were irradiated for 20 s at 1.2 W/cm2. Kinetic data were curve-fitted to exponential growth functions and key parameters analyzed by ANOVA and post-hoc tests (α = 0.05). RESULTS I(t) plots looked initially similar to bulk creep/recovery: rapid deformation plus viscoelastic response; then, upon unloading: rapid (elastic) recovery followed by partial viscoelastic recovery. However, unlike multiply irradiated and stored bulk-creep specimens, the present specimens were exposed to only 3 or 5 s "occlusal" irradiation; generating "hard" surfaces. Subsequently, during the 2 h indentation, the polymer matrix network continued to harden and consolidate. Upon initial loading, I(t) reached 2-3% indentation, depending upon the formulation. Upon unloading at 2 h, elastic recovery was only ca. 1 %. Delayed loading for 24 h, generated I(t) plots of significantly reduced magnitude. Most importantly, however, the I(t) plots for ECeram and EFlow, after 20 s irradiation, showed I(t) magnitudes quite comparable to the PFill and PFlow rapid-cure composites. SIGNIFICANCE Macroscopic indentation creep has been shown to be a workable procedure that can be applied to rapid-cure materials to assess their immediate surface integrity and developing viscoelastic characteristics. The applied stress of 14 MPa was relatively severe and the indentation/recovery profiles of PowerFill materials with only 3 or 5 s irradiation demonstrated comparability with their established 20 s cure siblings, evidencing the suitability of the PowerCure system for clinical application.
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Affiliation(s)
- David C Watts
- Biomaterials Science, Division of Dentistry, School of Medical Sciences, University of Manchester, UK; Photon Science Institute, University of Manchester, UK.
| | - Hamad Algamaiah
- Biomaterials Science, Division of Dentistry, School of Medical Sciences, University of Manchester, UK; Department of Restorative Dental Science, College of Dentistry, King Saud University, Saudi Arabia.
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18
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Kim K, Sinha J, Gao G, Childress KK, Sartor SM, Salazar AM, Huang S, Musgrave CB, Stansbury JW. High-Efficiency Radical Photopolymerization Enhanced by Autonomous Dark Cure. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Kangmin Kim
- Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Jasmine Sinha
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Guangzhe Gao
- Materials Science and Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Kimberly K. Childress
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Steven M. Sartor
- Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Austyn M. Salazar
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Sijia Huang
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Charles B. Musgrave
- Chemistry, University of Colorado, Boulder, Colorado 80309, United States
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
- Materials Science and Engineering, University of Colorado, Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Jeffrey W. Stansbury
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
- Craniofacial Biology, School of Dental Medicine, Aurora, Colorado 80045, United States
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19
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Limited reciprocity in curing efficiency of bulk-fill resin-composites. Dent Mater 2020; 36:997-1008. [PMID: 32499190 DOI: 10.1016/j.dental.2020.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 11/21/2022]
Abstract
OBJECTIVE The aim of the study was to identify experimental limits of the general reciprocity hypothesis that the same photo-cure outcomes will result from applying essentially constant energy densities, despite reciprocal variations in the irradiance and irradiation time-period, for a representative set of bulk fill (BF) and non-BF resin composites. METHODS Six BF and two non-BF resin-composites were selected. The unset pastes were inserted into white acetal molds (5mm id) with (n=6) depths (1, 2, 3, 4, 5 and 6mm). Three light curing units (LCUs) of increasing radiant emittance capability: 1200, 2000 and 3200mW/cm2 were used. Composite specimen groups (n=3, per depth, per LCU) were irradiated on the upper surface only. For each specific composite, the irradiation times for each LCU were reduced reciprocally, as the LCU irradiance increased, to deliver a constant energy density (J/cm2) to that composite. However, the required energy density for a given composite differed in accordance with each composite manufacturer recommendations. After storing for 24h at 37°C, light transmission measurements were made through each specimen and re-expressed as Apparent Absorbance (A'). Vickers hardness (HV) measurements (n=10) were made on both top and bottom surfaces, for each specimen, and HVversus "depth" profile plots created. From the top-surface data, a Depth-of-Cure parameter could be derived. Data were statistically evaluated for differences between top and bottom HV values and for other predefined variables of interest. RESULTS Irradiation with the LCU of 1200mW/cm2 generally gave the highest HV/depth for most materials tested compared to the other curing lights with higher power output, regardless of top and bottom measurements (p<0.001). However, this difference was material-dependent. With one BF composite, 1200 and 2000mW/cm2 irradiance did not show a significant difference between top and bottom HV. Composites with higher translucency showed reduced differences in top/bottom HV than more opaque composites. SIGNIFICANCE Reciprocity was found to be limited with most materials examined, such that irradiance periods of 10s, gave generally better HV outcomes than by using LCUs of superior radiant emittance while reciprocally reducing irradiance time to maintain constant dose of energy density.
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20
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Ilie N, Watts DC. Outcomes of ultra-fast (3 s) photo-cure in a RAFT-modified resin-composite. Dent Mater 2020; 36:570-579. [DOI: 10.1016/j.dental.2020.02.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 11/28/2022]
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21
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Palagummi SV, Hong T, Wang Z, Moon CK, Chiang MYM. Resin viscosity determines the condition for a valid exposure reciprocity law in dental composites. Dent Mater 2019; 36:310-319. [PMID: 31866065 DOI: 10.1016/j.dental.2019.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 12/04/2019] [Accepted: 12/04/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To provide conditions for the validity of the exposure reciprocity law as it pertains to the photopolymerization of dimethacrylate-based dental composites. METHODS Composites made from different mass ratios of resin blends (Bis-GMA/TEGDMA and UDMA/TEGDMA) and silanized micro-sized glass fillers were used. All the composites used camphorquinone and ethyl 4-dimethylaminobenzoate as the photo initiator system. A cantilever beam-based instrument (NIST SRI 6005) coupled with NIR spectroscopy and a microprobe thermocouple was used to simultaneously measure the degree of conversion (DC), the polymerization stress (PS) due to the shrinkage, and the temperature change (TC) in real time during the photocuring process. The instrument has an integrated LED light curing unit providing irradiances ranging from 0.01W/cm2 to 4W/cm2 at a peak wavelength of 460nm (blue light). Vickers hardness of the composites was also measured. RESULTS For every dental composite there exists a minimum radiant exposure required for an adequate polymerization (i.e., insignificant increase in polymerization with any further increase in the radiant exposure). This minimum predominantly depends on the resin viscosity of composite and can be predicted using an empirical equation established based on the test results. If the radiant exposure is above this minimum, the exposure reciprocity law is valid with respect to DC for high-fill composites (filler contents >50% by mass) while invalid for low-fill composites (that are clinically irrelevant). SIGNIFICANCE The study promotes better understanding on the applicability of the exposure reciprocity law for dental composites. It also provides a guidance for altering the radiant exposure, with the clinically available curing light unit, needed to adequately cure the dental composite in question.
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Affiliation(s)
- Sri Vikram Palagummi
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Taeseung Hong
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, MD, United States; Department of Materials Science and Engineering, Pukyong National University, Busan, Republic of Korea
| | - Zhengzhi Wang
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, Hubei, China
| | - Chang Kwon Moon
- Department of Materials Science and Engineering, Pukyong National University, Busan, Republic of Korea
| | - Martin Y M Chiang
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, MD, United States.
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22
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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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23
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Sirovica S, Skoda MWA, Podgorski M, Thompson PBJ, Palin WM, Guo Y, Smith AJ, Dewan K, Addison O, Martin RA. Structural Evidence That the Polymerization Rate Dictates Order and Intrinsic Strain Generation in Photocured Methacrylate Biomedical Polymers. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Slobodan Sirovica
- Aston Institute of Materials Research, School of Engineering & Applied Science, University of Aston, Birmingham B4 7ET, U.K
| | - Maximilian W. A. Skoda
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K
| | - Maciej Podgorski
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB Boulder, Colorado 80309, United States
- Faculty of Chemistry, Department of Polymer Chemistry, Maria Curie-Sklodowska University, Gliniana Street 33, 20-614 Lublin, Poland
| | | | - William M. Palin
- College of Medical and Dental Sciences, Institute of Clinical Sciences, School of Dentistry, University of Birmingham, Mill Pool Way,
Edgbaston, Birmingham B5 7EG, U.K
| | - Yilan Guo
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton T6G 1C9, Canada
| | - Andrew J. Smith
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Karun Dewan
- College of Medical and Dental Sciences, Institute of Clinical Sciences, School of Dentistry, University of Birmingham, Mill Pool Way,
Edgbaston, Birmingham B5 7EG, U.K
| | - Owen Addison
- College of Medical and Dental Sciences, Institute of Clinical Sciences, School of Dentistry, University of Birmingham, Mill Pool Way,
Edgbaston, Birmingham B5 7EG, U.K
- Faculty of Medicine and Dentistry, University of Alberta, Edmonton T6G 1C9, Canada
| | - Richard A. Martin
- Aston Institute of Materials Research, School of Engineering & Applied Science, University of Aston, Birmingham B4 7ET, U.K
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Impact of thiourethane filler surface functionalization on composite properties. J Appl Polym Sci 2019. [DOI: 10.1002/app.47687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Faria-e-Silva AL, dos Santos A, Girotto EM, Pfeifer CS. Impact of thiourethane filler surface functionalization on composite properties. J Appl Polym Sci 2019; 136:47687. [PMID: 31736511 PMCID: PMC6858055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Thiourethane oligomers added to methacrylate matrices improve fracture toughness and reduce polymerization stress. In this study, the oligomers are added to the surface of inorganic fillers in the formulation of resin composites. Systematically varied fillers treated either with the thiourethane or a methacrylate silane control are tested. Thiourethane reduces the rate of polymerization of light-cured composites but does not affect the final degree of conversion (DC). Filler functionalization with thiourethane increases the depth of polymerization, in filler type-dependent fashion. Thiourethane reduces the polymerization stress for all fillers. The findings suggest that this approach results in the same general effects with the addition of thiourethanes directly to the matrix. This is accomplished with a lower overall concentration of thiourethane, and with no prejudice to the handling characteristics of the material.
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Affiliation(s)
- André L. Faria-e-Silva
- Department of Dentistry, Federal University of Sergipe, Rua Claudio Batista s/n, Bairro Sanatório, Aracaju, SE, Brazil – 49060-100
| | - Andressa dos Santos
- Graduate program in Chemistry, State University of Maringa, Av. Colombo 5790, Jardim Universitário, Maringá, PR, Brazil – 87020-900
| | - Emerson M. Girotto
- Department of Chemistry, State University of Maringa, Av. Colombo 5790, Jardim Universitário, Maringá, PR, Brazil – 87020-900
| | - Carmem S. Pfeifer
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Oregon Health & Science University, 2730 SW Moody Ave, 97201, Portland, OR, USA
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Childress KK, Kim K, Glugla DJ, Musgrave CB, Bowman CN, Stansbury JW. Independent Control of Singlet Oxygen and Radical Generation via Irradiation of a Two-Color Photosensitive Molecule. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00424] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Kimberly K. Childress
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303, United States
| | - Kangmin Kim
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, United States
| | - David J. Glugla
- Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, 425 UCB, Boulder, Colorado 80303, United States
| | - Charles B. Musgrave
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303, United States
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, United States
- Materials Science and Engineering Program, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Christopher N. Bowman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303, United States
- Materials Science and Engineering Program, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, United States
| | - Jeffrey W. Stansbury
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303, United States
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Denver, 12800 East 19th Avenue, Aurora, Colorado 80045, United States
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Abstract
PURPOSE There has been a recent explosion in the variety of techniques used to accomplish corneal cross-linking (CXL) for the treatment of ectatic corneal diseases. To understand the success or failure of various techniques, we review the physicochemical basis of corneal CXL and re-evaluate the current principles and long-standing conventional wisdom in the light of recent, compelling, and sometimes contradictory research. METHODS Two clinicians and a medicinal chemist developed a list of current key topics, controversies, and questions in the field of corneal CXL based on information from current literature, medical conferences, and discussions with international practitioners of CXL. RESULTS Standard corneal CXL with removal of the corneal epithelium is a safe and efficacious procedure for the treatment of corneal ectasias. However, the necessity of epithelium removal is painful for patients, involves risk and requires significant recovery time. Attempts to move to transepithelial corneal CXL have been hindered by the lack of a coherent understanding of the physicochemistry of corneal CXL. Misconceptions about the applicability of the Bunsen-Roscoe law of reciprocity and the Lambert-Beer law in CXL hamper the ability to predict the effect of ultraviolet A energy during CXL. Improved understanding of CXL may also expand the treatment group for corneal ectasia to those with thinner corneas. Finally, it is essential to understand the role of oxygen in successful CXL. CONCLUSIONS Improved understanding of the complex interactions of riboflavin, ultraviolet A energy and oxygen in corneal CXL may provide a successful route to transepithelial corneal CXL.
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Al-Zain AO, Eckert GJ, Platt JA. The Influence of Distance on Radiant Exposure and Degree of Conversion Using Different Light-Emitting-Diode Curing Units. Oper Dent 2019; 44:E133-E144. [DOI: 10.2341/18-004-l] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
Objectives:
To investigate the influence of curing distance on the degree of conversion (DC) of a resin-based composite (RBC) when similar radiant exposure was achieved using six different light-curing units (LCUs) and to explore the correlation among irradiance, radiant exposure, and DC.
Methods and Materials:
A managing accurate resin curing-resin calibrator system was used to collect irradiance data for both top and bottom specimen surfaces with a curing distance of 2 mm and 8 mm while targeting a consistent top surface radiant exposure. Square nanohybrid-dual-photoinitiator RBC specimens (5 × 5 × 2 mm) were cured at each distance (n=6/LCU/distance). Irradiance and DC (micro-Raman spectroscopy) were determined for the top and bottom surfaces. The effect of distance and LCU on irradiance, radiant exposure, and DC as well as their linear associations were analyzed using analysis of variance and Pearson correlation coefficients, respectively (α=0.05).
Results:
While maintaining a similar radiant exposure, each LCU exhibited distinctive patterns in decreased irradiance and increased curing time. No significant differences in DC values (63.21%-70.28%) were observed between the 2- and 8-mm distances, except for a multiple-emission peak LCU. Significant differences in DC were detected among the LCUs. As expected, irradiance and radiant exposure were significantly lower on the bottom surfaces. However, a strong correlation between irradiance and radiant exposure did not necessarily result in a strong correlation with DC.
Conclusions:
The RBC exhibited DC values >63% when the top surface radiant exposure was maintained, although the same values were not reached for all lights. A moderate-strong correlation existed among irradiance, radiant exposure, and DC.
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Affiliation(s)
- AO Al-Zain
- Afnan O Al-Zain, BDS, MSD, PhD, King Abdulaziz University, Faculty of Dentistry, Restorative Dentistry Department, Jeddah, Saudi Arabia
| | - GJ Eckert
- George J Eckert, MS, Indiana University School of Medicine, Division of Biostatistics, Indianapolis, IN, USA
| | - JA Platt
- Jeffrey A Platt, DDS, MS, Indiana University, Department of Biomedical and Applied Sciences, Indianapolis, IN, USA
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29
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Quantitative comparison of photo- and electron-beam polymerizations based on equivalent initiation energy. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.12.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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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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Vara J, Gualdesi MS, Aiassa V, Ortiz CS. Evaluation of physicochemical properties and bacterial photoinactivation of phenothiazine photosensitizers. Photochem Photobiol Sci 2019; 18:1576-1586. [DOI: 10.1039/c8pp00584b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report herein the physicochemical properties and antimicrobial activity of a new monobrominated derivative of Azure B and its parent compound.
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Affiliation(s)
- Jimena Vara
- Departamento de Ciencias Farmacéuticas
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
- Argentina
- UNITEFA-CONICET
| | - María S. Gualdesi
- Departamento de Ciencias Farmacéuticas
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
- Argentina
| | - Virginia Aiassa
- Departamento de Ciencias Farmacéuticas
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
- Argentina
- UNITEFA-CONICET
| | - Cristina S. Ortiz
- Departamento de Ciencias Farmacéuticas
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
- Argentina
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Song L, Ye Q, Ge X, Misra A, Tamerler C, Spencer P. New silyl-functionalized BisGMA provides autonomous strengthening without leaching for dental adhesives. Acta Biomater 2019; 83:130-139. [PMID: 30366133 DOI: 10.1016/j.actbio.2018.10.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/30/2018] [Accepted: 10/22/2018] [Indexed: 12/27/2022]
Abstract
Resin-based composite has overtaken dental amalgam as the most popular material for direct restorative dentistry. In spite of this popularity the clinical lifetime of composite restorations is threatened by recurrent decay. Degradation of the adhesive leads to gaps at the composite/tooth interface-bacteria, bacterial by-products and fluids infiltrate the gaps leading to recurrent decay and composite restoration failure. The durability of resin-dentin bonds is a major problem. We address this problem by synthesizing silyl-functionalized BisGMA (e.g., silyl-BisGMA), formulating dental adhesives with the new monomer and determining the physicochemical properties and leaching characteristics of the silyl-BisGMA adhesives. Silyl-BisGMA was synthesized by stoichiometric amounts of BisGMA and 3-isocyanatopropyl trimethoxysilane (IPTMS). The control adhesive was a mixture based on HEMA/BisGMA (45/55, w/w). In the experimental formulations, BisGMA was partially or completely replaced by silyl-BisGMA. Water miscibility, polymerization behavior (Fourier transform infrared spectroscopy, FTIR), thermal property (modulated differential scanning calorimetry, MDSC), mechanical properties in dry and wet conditions (dynamic mechanical analysis, DMA), and leached species (HPLC) were investigated. Data from all tests were submitted to appropriate statistical analysis (α = 0.05). Silyl-BisGMA-containing adhesives exhibited comparable water miscibility, lower viscosities, and significantly improved degree of conversion of CC bond as compared to the control. After 4 weeks aqueous aging, the glass transition temperature and rubbery moduli of the experimental copolymers were significantly greater than the control (p < 0.05). HPLC results indicated a substantial reduction of leached HEMA (up to 99 wt%) and BisGMA (up to 90 wt%). By introducing silyl-functional group, the new BisGMA derivative exhibited potential as a monomer that can lead to dental adhesives with improved mechanical properties and reduced leaching under conditions relevant to the oral environment. STATEMENT OF SIGNIFICANCE: The low-viscosity adhesive that bonds the composite to the tooth (enamel and dentin) is intended to seal and stabilize the composite/tooth interface, but it degrades leading to a breach at the composite/tooth margin. As the most popular crosslinking monomer in adhesives, Bisphenol A-glycerolate dimethacrylate (BisGMA) has limitations, e.g. susceptible to hydrolysis and concomitant property degradation. A methoxysilyl-functionalized BisGMA derivative (silyl-BisGMA) was introduced in this work to respond to these limitations. Our results indicated that by introducing silyl-BisGMA, higher crosslinked networks were obtained without sacrificing the homogeneity, and the leached amount of HEMA was reduced up to 99%. This novel resin offers potential benefits including prolonging the functional lifetime of dental resin materials.
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Uzcategui AC, Muralidharan A, Ferguson VL, Bryant SJ, McLeod RR. Understanding and Improving Mechanical Properties in 3D printed Parts Using a Dual-Cure Acrylate-Based Resin for Stereolithography. ADVANCED ENGINEERING MATERIALS 2018; 20:1800876. [PMID: 30766445 PMCID: PMC6370025 DOI: 10.1002/adem.201800876] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Indexed: 05/20/2023]
Abstract
Application of 3D printed structures via stereolithography (SLA) is limited by imprecise dimensional control and inferior mechanical properties. These challenges is attributed to poor understanding ofpolymerization behavior during the printing process and inadequate post-processing methods. The former via a modified version of Jacob's working curve equation that incorporates the resin's sub-linear response to irradiation intensity is addressed by the authors. This new model provides a more accurate approach to select 3D printing parameters given a desired z-resolution and conversion profile along the depth of the printed part. The authors use this improved model to motivate a novel material design that can be post-processed to be indistinguishable from the polymer at 100% conversion. This approach employs a dual initiating system in which photo-initiated printing is followed by a thermal post-cure to achieve uniform conversion. The authors show that this approach enables fast printing times (10 s per layer), exceptional horizontal resolution (1-10 microns), precise control over vertical resolution, and decreased surface corrugations on a 10's of microns scale. The techniques described herein use an acrylate-based SLA resin, but the approach can be extended to other monomer systems to simultaneously achieve predictable properties and dimensions that are critical for application of additive manufacturing in load-bearing applications.
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Affiliation(s)
| | - Archish Muralidharan
- Materials Science and Engineering University of Colorado Boulder Boulder, CO 80309, USA
| | - Virginia L Ferguson
- Department of Mechanical Engineering University of Colorado Boulder Boulder, CO 80309, USA
| | - Stephanie J Bryant
- Department of Chemical and Biological Engineering University of Colorado Boulder Boulder, CO 80309, USA
| | - Robert R McLeod
- Department of Electrical Computer and Energy Engineering University of Colorado Boulder Boulder, CO 80309, USA
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Lempel E, Őri Z, Szalma J, Lovász BV, Kiss A, Tóth Á, Kunsági-Máté S. Effect of exposure time and pre-heating on the conversion degree of conventional, bulk-fill, fiber reinforced and polyacid-modified resin composites. Dent Mater 2018; 35:217-228. [PMID: 30503020 DOI: 10.1016/j.dental.2018.11.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 10/03/2018] [Accepted: 11/14/2018] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To determine the degree of conversion (DC) of different type of resin-based composites (RBC) in eight-millimeter-deep clinically relevant molds, and investigate the influence of exposure time and pre-heating on DC. METHODS Two-millimeter-thick samples of conventional sculptable [FiltekZ250 (FZ)], flowable [Filtek Ultimate Flow (FUF)] and polyacid-modified [Twinky Star Flow (TS)] RBCs, and four-millimeter-thick samples of flowable bulk-fill [Filtek Bulk Fill Flow (FBF), Surefil SDR (SDR)] and sculptable fibre-reinforced [EverX Posterior (EX)] RBCs were prepared in an eight-millimeter-deep mold. The RBCs temperature was pre-set to 25, 35 and 55°C. The RBCs were photopolymerized with the recommended and its double exposure time. The DC at the top and bottom was measured with micro-Raman spectroscopy. Data were analyzed with ANOVA and Scheffe post-hoc test (p<0.05). RESULTS The differences in DC% between the top/bottom and the recommended/extended exposure time were significant for the materials, except SDR (64.5/63.0% and 67.4/63.0%). FUF (69.0% and 53.4%) and TS (64.9% and 60.9%) in 2mm provided higher DC% at the top and bottom with the recommended curing time, compared to the other materials, except SDR. Pre-heating had negative effect on DC at the bottom in flowable RBCs (FUF: 48.9%, FBF: 36.7%, SDR: 43%, TS: 54.7%). Pre-heating to 55 °C significantly increased the DC% in fibre-reinforced RBC (75.0% at the top, 64.7% at the bottom). SIGNIFICANCE Increased exposure time improves the DC for each material. Among bulk-fills, only SDR performed similarly, compared to the two-millimeter-thick flowable RBCs. Pre-heating of low-viscosity RBCs decreased the DC% at the bottom. Pre-heating of fibre-reinforced RBC to 55°C increased the DC% at a higher rate than the extended curing time.
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Affiliation(s)
- Edina Lempel
- Department of Restorative Dentistry and Periodontology, University of Pécs, Pécs, Hungary.
| | - Zsuzsanna Őri
- Department of General and Physical Chemistry, University of Pécs, 6 Ifjúság Street, Pécs, H-7624, Hungary; János Szentágothai Research Center, 20 Ifjúság Street, Pécs, H-7624, Hungary
| | - József Szalma
- Department of Oral and Maxillofacial Surgery, University of Pécs, Pécs, Hungary
| | - Bálint Viktor Lovász
- Department of Restorative Dentistry and Periodontology, University of Pécs, Pécs, Hungary
| | - Adél Kiss
- Department of Restorative Dentistry and Periodontology, University of Pécs, Pécs, Hungary
| | - Ákos Tóth
- Faculty of Sciences, University of Pécs Pécs, Hungary
| | - Sándor Kunsági-Máté
- Department of General and Physical Chemistry, University of Pécs, 6 Ifjúság Street, Pécs, H-7624, Hungary; János Szentágothai Research Center, 20 Ifjúság Street, Pécs, H-7624, Hungary
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Examining the Effect of Radiant Exposure on Commercial Photopolimerizable Dental Resin Composites. Dent J (Basel) 2018; 6:dj6040055. [PMID: 30301279 PMCID: PMC6313541 DOI: 10.3390/dj6040055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/04/2018] [Indexed: 11/17/2022] Open
Abstract
The objective of this study was to evaluate the effect of radiant exposure on the chemical and physical properties of four commercial dental resin composites. The four dental resin composites used were Kalore, Admira, Tetric N-Ceram Bulk Fill, and Filtek Z350 XT. The composites were subjected to three curing protocols: 1000 mW/cm2 for 5 s, 1000 mW/cm2 for 10 s, and 400 mW/cm2 for 25 s. The flexural strength, elastic modulus, water sorption, water solubility, degree of conversion, and polymerization shrinkage were evaluated. The results were analyzed by means of ANOVA and Tukey tests. For Admira and Kalore, significant differences between light exposure protocols were observed for the elastic modulus (p < 0.001), which was higher when a higher amount of radiant exposure was used. For Filtek Z350, differences were only observed for the degree of conversion (p < 0.001), and a higher amount of radiant exposure allowed us to obtain higher values. The Tetric N-Ceram Bulk Fill analysis showed significant differences for the elastic modulus and water sorption (p < 0.001), and specimens that had been subject to a radiant exposure of 10 J/cm2 showed a higher elastic modulus. In most cases, the physical and mechanical properties analyzed were not affected by different radiant exposure values. Other resin-based composite (RBC) characteristics seem to have a greater influence on material properties.
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Al-Jawad M, Addison O, Sirovica S, Siddiqui S, Martin RA, Wood DJ, Watts DC. Intracoronal stress transfer through enamel following RBC photopolymerisation: A synchrotron X-ray study. Dent Mater 2018; 34:1426-1439. [PMID: 30119841 DOI: 10.1016/j.dental.2018.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/29/2018] [Accepted: 07/29/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To measure the spatial distribution of crystallographic strain in tooth enamel induced by the photo-polymerisation of a dimethacrylate resin based composite cavity restoration. METHODS Six sound first premolar teeth, allocated into two groups (n=3), were prepared with mesio-occlusal distal cavities. The enamel was machined at the point of maximum convexity on the outer tooth to create a vertical fin of thickness 100μm and 0.5mm depth to allow for synchrotron X-ray diffraction measurements. 2D diffraction patterns were used to determine crystallite orientation and quantify changes in the hydroxyapatite crystal lattice parameters, before and after photo-polymerisation of a composite material placed in the cavity, to calculate strain in the respective axis. The composite was photo-polymerised with either relatively high (1200mWcm-2, group 1) or low (480mWcm-2, group 2) irradiances using LED or quartz halogen light sources, respectively. A paired t-test was used to determine significant differences in strain between irradiance protocols at ɑ=0.001. RESULTS Photo-polymerisation of the composite in the adjacent cavity induced significant changes in both the crystallographic c and a axes of the enamel measurement area. However the magnitude of strain was low with ∼0.1% difference before and after composite photo-polymerisation. Strain in enamel was not uniformly distributed and varied spatially as a function of crystallite orientation. Increased alignment of crystallites perpendicular to the cavity wall was associated with higher c axis strain. Additionally, strain was significantly greater in the c (p<0.001) and a axis (p<0.001) when using a high irradiance photo-polymerisation protocol. SIGNIFICANCE Although cuspal deflection is routinely measured to indirectly assess the 'global' effect of composite shrinkage on the tooth-restoration complex, here we show that absolute strains generated in enamel are low, indicating strain relief mechanisms may be operative. The use of low irradiance protocols for photo-polymerisation resulted in reduced strain.
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Affiliation(s)
- Maisoon Al-Jawad
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Owen Addison
- Biomaterials Unit, University of Birmingham School of Dentistry, Birmingham, UK; University of Alberta, School of Dentistry, Edmonton, AB, Canada.
| | - Slobodan Sirovica
- University of Alberta, School of Dentistry, Edmonton, AB, Canada; Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - Samera Siddiqui
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Richard A Martin
- Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - David J Wood
- Biomaterials and Tissue Engineering Research Group, School of Dentistry, University of Leeds, Leeds, UK
| | - David C Watts
- School of Medical Sciences and Photon Science Institute, University of Manchester, UK
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Ye Q, Abedin F, Parthasarathy R, Spencer P. Photoinitiators in Dentistry: Challenges and Advances. PHOTOPOLYMERISATION INITIATING SYSTEMS 2018. [DOI: 10.1039/9781788013307-00297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Photopolymerization is used in a wide range of clinical applications in dentistry and the demand for dental materials that can restore form, function and esthetics is increasing rapidly. Simultaneous with this demand is the growing need for photoinitiators that provide effective and efficient in situ polymerization of dental materials using visible light irradiation. This chapter reviews the fundamentals of Type I and II photoinitiators. The advantages and disadvantages of these photoinitiators will be considered with a particular focus on parameters that affect the polymerization process in the oral cavity. The chapter examines recent developments in photoinitiators and opportunities for future research in the design and development of photoinitiators for dental applications. Future research directions that employ computational models in conjunction with iterative synthesis and experimental methods will also be explored in this chapter.
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Affiliation(s)
- Qiang Ye
- Institute for Bioengineering Research, School of Engineering, University of Kansas 1530 W. 15th St Lawrence KS 66045 USA
| | - Farhana Abedin
- Electromechanical Engineering Technology program, College of Engineering, California State Polytechnic University Pomona 3801 W. Temple Ave Pomona CA 91768 USA
| | - Ranganathan Parthasarathy
- Nanomaterials Research Lab, Tennessee State University 3500 John A Merritt Blvd Nashville TN 37209 USA
| | - Paulette Spencer
- Institute for Bioengineering Research, School of Engineering, University of Kansas 1530 W. 15th St Lawrence KS 66045 USA
- Department of Mechanical Engineering, University of Kansas 1530 W. 15th St Lawrence KS 66045 USA
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Zakharina MY, Fedoseev VB, Chechet YV, Chesnokov SA, Shaplov AS. Effect of Viscosity of Dimethacrylate Ester-Based Compositions on the Kinetics of Their Photopolymerization in Presence of o-Quinone Photoinitiators. POLYMER SCIENCE SERIES B 2018. [DOI: 10.1134/s1560090417060100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Photo-calorimetry method optimization for the study of light-initiated radical polymerization of dental resins. POLYMER 2018. [DOI: 10.1016/j.polymer.2017.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Schissel SM, Lapin SC, Jessop JL. Characterization and prediction of monomer-based dose rate effects in electron-beam polymerization. Radiat Phys Chem Oxf Engl 1993 2017. [DOI: 10.1016/j.radphyschem.2017.05.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
The ability to light cure resins 'on demand' in the mouth has revolutionized dentistry. However, there is a widespread lack of understanding of what is required for successful light curing in the mouth. Most instructions simply tell the user to 'light cure for xx seconds' without describing any of the nuances of how to successfully light cure a resin. This article provides a brief description of light curing. At the end, some recommendations are made to help when purchasing a curing light and how to improve the use of the curing light.
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Affiliation(s)
- Richard B T Price
- Department of Dental Clinical Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
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Faria-e-Silva AL, Fanger C, Nguyen L, Howerton D, Pfeifer CS. Impact of Material Shade and Distance from Light Curing Unit Tip on the Depth of Polymerization of Composites. Braz Dent J 2017; 28:632-637. [DOI: 10.1590/0103-6440201701727] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 08/29/2017] [Indexed: 11/21/2022] Open
Abstract
Abstract This study aimed to evaluate the effect of the composite shade and distance from the light-curing unit (LCU) tip on the irradiance reaching the bottom of composite disks and on the depth of polymerization. Composites of three shades (opaque - OXDC, bleach - BXL, and A2) were inserted into molds with 3-mm of thickness positioned over a spectrometer and photo-activated with the LCU (Bluephase) tip placed at 0 or 1 cm from the composite surface. The mean irradiance reaching the bottom of composite was recorded during the entire photo-activation (30 s). Specimens (2 x 2 x 4 mm) were polymerized and used to map the degree of conversion achieved in different depths from irradiated surface. Specimens were sectioned into slices that were positioned over the platform of the infra-red microscope connected to the spectrometer to map the conversion. The conversion was measured in eight different depths every 500-µm. Increasing the distance of LCU tip reduced the irradiance only for A2. Interposing OXDC disks resulted in lowest values of irradiance and A2 the highest one. A tendency to decrease the conversion was observed towards the bottom of specimens for all experimental conditions, and the slope was more accentuated for OXDC. Differences among shades and distances from LCU tip were evident only beyond 1.5-2.0 mm of depth. In conclusion, both composite shade and distance from LCU tip might affect the light-transmission and depth of polymerization, while the effect of last was more pronounced.
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Faria-E-Silva AL, Covell DA, Ferracane JL, Pfeifer CS. Effectiveness of high irradiance for short-time exposures on polymerization of composite under metal brackets. Angle Orthod 2017; 87:834-840. [PMID: 28841034 DOI: 10.2319/051817-338.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To evaluate the effect of different curing modes available in a dental light-curing unit on degree of conversion (DC) of a composite photoactivated under a metal orthodontic bracket. MATERIALS AND METHODS The average irradiance and total energy delivered by three curing modes (standard, high, and extra power) of a multiwave LED unit (Valo Cordless, Ultradent Products, South Jordan, Utah) were measured using the longest time available for each mode (20, 4, and 3 seconds, respectively). Brackets (n = 3/group) were bonded to molar epoxy resin replicas using each curing mode. Mesiodistal sections, 0.5 mm thick, were assessed using an infrared spectrometer microscope. Spectra of composite beneath the brackets were sequentially collected using the mapping tool in near-infrared (NIR)-transmittance mode. Composite conversion was mapped between the mesial and distal edges of the bracket base using 400-μm steps for a total of 10 measurements per specimen. Data from irradiance and total energy were analyzed by one-way ANOVA, while data of DC were analyzed with two-way repeated measures ANOVA (α = 0.05). RESULTS The highest DC values were observed for standard power (mean 56%, P < .05), while no difference was observed between high (50%) and extra power (49%) modes. Regarding the site of measurement, higher DC was observed close to the bracket edges (52%, P < .05). CONCLUSIONS The use of high irradiance for a short time slightly reduced the DC. The small magnitude of reduction suggests that use of a high irradiance protocol is a clinically valid approach when bonding metal brackets.
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Impact of thio-urethane additive and filler type on light-transmission and depth of polymerization of dental composites. Dent Mater 2017; 33:1274-1285. [PMID: 28807329 DOI: 10.1016/j.dental.2017.07.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/10/2017] [Accepted: 07/27/2017] [Indexed: 11/21/2022]
Abstract
OBJECTIVE This study evaluated the effects of filler type and the addition of thio-urethane oligomers on light-transmission, polymerization kinetics and depth of cure of resin composites. METHODS BisGMA:UDMA:TEGMA (5:3:2wt%) were mixed with 0 (control) or 20wt% thio-urethane. Fillers with various sizes and refractive indices were included and refractive index (RI) measured. Unfilled resins were used as controls. The RIs of materials were measured before and after polymerization. The irradiance reaching the bottom of 3-mm thick specimens was measured during the polymerization. Degree of conversion to a depth of 5mm was mapped. An optical bench was used to simultaneously follow conversion and light transmission. RESULTS The addition of thio-urethane increased the RI for all composites. As expected, RI also increased with conversion for all materials. The one exception was for the material filled with OX-50, in which the RI of the composite decreased with conversion. In this case, the irradiance at the bottom of the 3mm specimen was also the lowest among all groups. The addition of thio-urethanes had only minimal effect on light transmission within a filler type, but led to increased conversion in depth for all groups. The filler type itself had a greater effect on light transmission, and that correlated well with the degree of conversion. SIGNIFICANCE The effect of the thio-urethane addition on degree of conversion in depth was dependent on filler type. The additive can be tailored to improve the RI match with the filler to optimize light transmission in dental composites.
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Faria-E-Silva AL, Pfeifer CS. Delayed photo-activation and addition of thio-urethane: Impact on polymerization kinetics and stress of dual-cured resin cements. J Dent 2017; 65:101-109. [PMID: 28750778 DOI: 10.1016/j.jdent.2017.07.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/04/2017] [Accepted: 07/21/2017] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE 1) to determine the moment during the redox polymerization reaction of dual cure cements at which to photo-activate the material in order to reduce the polymerization stress, and 2) to evaluate possible synergistic effects between adding chain transfer agents and delayed photo-activation. METHODS The two pastes of an experimental dual-cure material were mixed, and the polymerization kinetics of the redox phase was followed. The moment when the material reached its maximum rate of redox polymerization (MRRP) of cement was determined. The degree of conversion (DC) and maximum rates of polymerization (Rpmax) were assessed for materials where: the photoactivation immediately followed material mixing, at MRRP, 1min before and 1min after MRRP. Thio-urethane (TU) additives were synthesized and added to the cement (20% wt), which was then cured under the same conditions. The polymerization kinetics was evaluated for both cements photo-activated immediately or at MRRP, followed by measurements of polymerization stress, flexural strength (FS) and elastic modulus (EM). Knoop hardness was measured before and after ethanol storage. RESULTS Photo-activating the cement at or after MRRP reduced the Rpmax and the polymerization stress. Addition of TU promoted additional and more significant reduction, while not affecting the Rpmax. Greater hardness loss was observed for cements with TU, but the final hardness was similar for all experimental conditions. Addition of TU slightly reduced the EM and did not affect the FS. CONCLUSION Delayed photo-activation and addition of TU significantly reduce the polymerization stress of dual-cured cements.
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Affiliation(s)
- André L Faria-E-Silva
- Department of Dentistry, Federal University of Sergipe, Rua Claudio Batista s/n, 49060-100, Aracaju, SE, Brazil
| | - Carmem S Pfeifer
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Oregon Health & Science University, 2730 SW Moody Ave, 97201, Portland, OR, USA.
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Effectiveness of high-power LEDs to polymerize resin cements through ceramics: An in vitro study. J Prosthet Dent 2017; 118:631-636. [PMID: 28385443 DOI: 10.1016/j.prosdent.2016.12.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 12/15/2016] [Accepted: 12/15/2016] [Indexed: 11/22/2022]
Abstract
STATEMENT OF PROBLEM The cementation of ceramic veneers using light-polymerized resin cement is largely dependent on the proper light activation of the cement. Light activation using high irradiance could shorten the time required to lute multiple restorations. PURPOSE The purpose of this in vitro study was to evaluate the light transmission of dental light-polymerizing units through ceramic cylinders and its effect on the polymerization kinetics of a resin cement. MATERIAL AND METHODS Ceramic ingots (IPS Empress Esthetic, shade ET1) were sectioned to produce cylinders 0.5, 1.0, and 2.0 mm thick. Two light-emitting diode units were evaluated: SmartLite Focus and Valo Cordless, the latter used in either Standard or Xtra Power (XP) modes. Light transmission (average of irradiance, total energy, and light-emission profile) through the cylinders was measured (n=3). The polymerization kinetics of a resin cement light polymerized through the ceramic was monitored for 5 minutes (n=3). The degree of conversion was measured again after 72 hours. Data were individually analyzed with 2-way ANOVA and the Tukey HSD test (α=.05). RESULTS Valo at XP presented the highest values of irradiance and SmartLite the lowest, irrespective of the ceramic thickness. Regarding the total energy, XP showed the lowest values. The total energy and irradiance lessened with the increase in ceramic thickness. In general, except for Valo at XP, the ceramic thickness did not affect the degree of conversion. Valo at XP and interposing 2.0 mm ceramic resulted in the lowest values of Rpmax. CONCLUSIONS The reduction of total energy and irradiance by ceramic interposition had only a slight effect on polymerization kinetics.
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AlShaafi MM. Factors affecting polymerization of resin-based composites: A literature review. Saudi Dent J 2017; 29:48-58. [PMID: 28490843 PMCID: PMC5411902 DOI: 10.1016/j.sdentj.2017.01.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 01/28/2017] [Accepted: 01/29/2017] [Indexed: 11/15/2022] Open
Abstract
AIM The aim of this review was to help clinicians improve their understanding of the polymerization process for resin-based composites (RBC), the effects of different factors on the process and the way in which, when controlled, the process leads to adequately cured RBC restorations. METHODS Ten factors and their possible effects on RBC polymerization are reviewed and discussed, with some recommendations to improve that process. These factors include RBC shades, their light curing duration, increment thickness, light unit system used, cavity diameter, cavity location, light curing tip distance from the curing RBC surface, substrate through which the light is cured, filler type, and resin/oral cavity temperature. CONCLUSION The results of the review will guide clinicians toward the best means of providing their patients with successfully cured RBC restorations.
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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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Berezin MP, Roshchupkin VP. Thermodynamic properties of three-dimensional radical polymerization of dimethacrylates and their relation to the structure and properties of network polymers. POLYMER SCIENCE SERIES B 2016. [DOI: 10.1134/s156009041606004x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Shrinkage behaviors of dental composite restorations—The experimental–numerical hybrid analysis. Dent Mater 2016; 32:e362-e373. [DOI: 10.1016/j.dental.2016.09.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 02/15/2016] [Accepted: 09/03/2016] [Indexed: 11/20/2022]
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50
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A novel photoinitiating system producing germyl radicals for the polymerization of representative methacrylate resins: Camphorquinone/R3GeH/iodonium salt. Dent Mater 2016; 32:1226-1234. [PMID: 27567540 DOI: 10.1016/j.dental.2016.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/30/2016] [Accepted: 07/16/2016] [Indexed: 11/22/2022]
Abstract
OBJECTIVES The aim of our study is to find an amine free photoinitiating system (PIS) for the polymerization of representative dental methacrylate resins. A photoinitiating system (PIS) based on camphorquinone (CQ)/triphenylgermanium hydride/diphenyl iodonium hexafluorophosphate is proposed and compared to the conventional CQ/amine couple. The polymerization monitoring of thin (∼20μm) and thick (1.4mm) samples of a bisphenol A-glycidyl methacrylate (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) blend (70%/30% w/w) and of a urethane dimethacrylate (UDMA) upon exposure to a commercial blue LED centered at 477nm under air or in laminate is described. Finally, the impact of the photoinitiating system composition on the final polymer color is evaluated in detail. METHODS FTIR and DSC experiments are used to record the photopolymerization profiles. ESR spectrometry and steady state photolysis are used to detect the produced radicals. Color measurements are carried out to determine the key parameters in the bleaching of the different dental formulations. RESULTS The efficiency of the newly proposed PISs for the photopolymerization of BisGMA/TEGDMA and UDMA for thin (20μm) or for thick (1.4mm) samples upon exposure to a dental blue LED under air is excellent. It is noticeably higher than that of the CQ/amine reference couple. Excellent bleaching properties are also observed under irradiation in presence of the new PISs. A good correlation is found between the sample bleaching and the amount of Ph3GeH in the formulation. The excited state processes could be established. The overall chemical mechanisms for the initiation step were also clarified.
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