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Fidalgo-Pereira R, Carvalho Ó, Catarino SO, Henriques B, Torres O, Braem A, Souza JCM. Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry. Clin Oral Investig 2023; 27:5679-5693. [PMID: 37592003 PMCID: PMC10492747 DOI: 10.1007/s00784-023-05189-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 07/28/2023] [Indexed: 08/19/2023]
Abstract
OBJECTIVES The aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content. METHODS Resin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation's tests, while Vicker's hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey's test (p < 0.05). RESULTS After polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78-80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content. CONCLUSIONS A high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites. CLINICAL SIGNIFICANCE The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.
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Affiliation(s)
- Rita Fidalgo-Pereira
- Center for Interdisciplinary Research in Health (CIIS), Faculty of Dental Medicine (FMD), Universidade Católica Portuguesa (UCP), 3504-505, Viseu, Portugal
- University Institute of Health Sciences (IUCS), CESPU, 4585-116, Gandra PRD, Portugal
| | - Óscar Carvalho
- Center for MicroElectroMechanical Systems (CMEMS-UMINHO), University of Minho, 4800-058, Guimarães, Portugal
- LABBELS Associate Laboratory, University of Minho, Guimarães, 4710-057, Braga, Portugal
| | - Susana O Catarino
- Center for MicroElectroMechanical Systems (CMEMS-UMINHO), University of Minho, 4800-058, Guimarães, Portugal
- LABBELS Associate Laboratory, University of Minho, Guimarães, 4710-057, Braga, Portugal
| | - Bruno Henriques
- Center for MicroElectroMechanical Systems (CMEMS-UMINHO), University of Minho, 4800-058, Guimarães, Portugal
- LABBELS Associate Laboratory, University of Minho, Guimarães, 4710-057, Braga, Portugal
- Ceramic and Composite Materials Research Group (CERMAT), Department of Mechanical Engineering (EMC), Federal University of Santa Catarina (UFSC), SC, 88040-900, Florianopolis, Brazil
| | - Orlanda Torres
- Oral Pathology and Rehabilitation Research Unit (UNIPRO), University Institute of Health Sciences (IUCS), CESPU, 4585-116, Gandra, Portugal
| | - Annabel Braem
- Department of Materials Engineering (MTM), Biomaterials and Tissue Engineering Research Group, KU Leuven, 3000, Leuven, Belgium
| | - Júlio C M Souza
- Center for MicroElectroMechanical Systems (CMEMS-UMINHO), University of Minho, 4800-058, Guimarães, Portugal.
- LABBELS Associate Laboratory, University of Minho, Guimarães, 4710-057, Braga, Portugal.
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Faria-E-Silva AL, Pfeifer CS. Development of dual-cured resin cements with long working time, high conversion in absence of light and reduced polymerization stress. Dent Mater 2020; 36:e293-e301. [PMID: 32636077 PMCID: PMC7529961 DOI: 10.1016/j.dental.2020.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/24/2020] [Accepted: 06/23/2020] [Indexed: 11/15/2022]
Abstract
OBJECTIVE This study evaluated the properties of experimental dual-cured cements containing thiourethane (TU) and low concentrations of p-Tolyldiethanolamnie (DHEPT) and benzoyl peroxide (BPO) as chemical initiators. METHODS BisGMA/TEGDMA-based dual-cured cement was formulated with 1.0 wt% DHEPT and 0.75 wt% BPO as initiators and used as control. The concentration of BPO was adjusted to 0.1 wt% in catalyst paste of experimental cements, and two base pastes containing TU and 0.5 wt% or 0.25 wt% of DHEPT were formulated. The rheological behavior and kinetics of polymerization of cements were assessed in the absence of light activation. The kinetics of polymerization was also evaluated for cements light-activated immediately or 5 min after the start of mixing. Polymerization stress, flexural strength and elastic modulus (n = 5) were also evaluated under these conditions. RESULTS Cements with TU presented lower viscosity than the control, improved working time (0.25% DHEPT > 0.5% DHEPT) and higher conversion in the absence of light-activation. Delaying the light-activation reduced the maximum rate of polymerization (Rpmax) but did not affect the conversion or stress. The addition of TU increased the Rpmax and conversion, and reduced the stress when compared to the control, without affecting the flexural strength. Except for the control with delayed light-activation (highest values), the other experimental conditions yielded similar modulus. SIGNIFICANCE Adding TU and using a low concentration of DHEPT/BPO resulted in dual-cured cements with longer working time, reduced polymerization stress and increased conversion even in the absence of light, with no significant effect on the mechanical properties.
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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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Erhardt MCG, Goulart M, Jacques RC, Rodrigues JA, Pfeifer CS. Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations. Dent Mater 2020; 36:829-837. [PMID: 32446504 PMCID: PMC7305981 DOI: 10.1016/j.dental.2020.03.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 03/15/2020] [Accepted: 03/16/2020] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion. METHODS Class I cavities (4mm depth×5mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature - activated for 20s); (2) Filtek Z250XT (at room temperature - activated for 40s); (3) Filtek Z250XT (pre-heated at 68°C - activated for 20s); (4) Filtek Z250XT (pre-heated at 68°C - activated for 40s); (5) Filtek BulkFill (at room temperature - activated for 20s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature - activated for 40s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α=5%). RESULTS Pre-heating the resin composite did not influence the intra-pulpal temperature (p=0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC. SIGNIFICANCE Resin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.
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Affiliation(s)
- M C G Erhardt
- Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - M Goulart
- Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - R C Jacques
- Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - J A Rodrigues
- Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - C S Pfeifer
- Oregon Health and Science University, Portland, OR, USA
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Fugolin AP, Costa AR, Kono E, Quirk E, Ferracane JL, Pfeifer CS. Influence of the organic matrix composition on the polymerization behavior and bulk properties of resin composites containing thiourethane-functionalized fillers. Eur Polym J 2020; 130:109664. [PMID: 32405085 PMCID: PMC7219823 DOI: 10.1016/j.eurpolymj.2020.109664] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES The incorporation of thiourethane-based oligomeric additives into resin composite formulations leads to improvement in mechanical properties and reduction in polymerization stress, but may increase viscosity. The objective of this study was to functionalize filler particle surfaces with thiourethane silane molecules and determine the impact of the inorganic filler loading and surface treatment on the behavior of experimental resin composites with systematically-varied organic matrices. METHODS Thiourethane oligomer was synthesized de novo, and grafted to the surface of 0.7um barium glass. BisGMA and TEGDMA (BT) were combined (at 30:70, 50:50 or 70:30 wt%) to 50 or 75 wt% of methacrylate (MA-Sil - control) or thiourethane-silanized (TU-Sil) particles. Composites were made polymerizable by the addition of 0.2 wt% BAPO and 0.05 wt% BHT was added as inhibitor. A mercury arc lamp (320-500 nm) at 800 mW/cm2 was used for all curing procedures. Kinetics of polymerization was assessed by near-IR spectroscopy in real time. Polymerization stress was determined with a cantilever system in real time (Bioman). Flexural modulus and strength were determined in 3-point bending (25x2x2 mm). Water sorption and solubility and film thickness were tested according to ISO 4049. Polymeric network characteristics were analyzed by dynamic mechanical analysis (DMA). Data was analyzed with two-way ANOVA/Tukey's test (95%). RESULTS Viscosity increased with the increase in BisGMA and/or filler amounts. Overall, TU-Sil containing composites showed delayed vitrification and higher final DC. Filler concentration did not affect DC neither flexural strength. DC decreased with increasing BisGMA content. Polymerization stress reduced and flexural modulus increased for higher filler content, especially for formulations containing TU-Sil particles. The water stability was positively affected by the increase in amount of BisGMA and inorganic filler particles. In terms of polymeric network, the addition of TU-Sil particles increased the Tg and decreased the E' and cross-link density. CONCLUSIONS With the exception of flexural modulus, all tested properties were significantly impacted by the matrix viscosity and/or the addition of TU-Sil filler particles. In general, the use of thiourethane oligomers as a silane coupling agent was able to reinforce the materials and reduce the polymerization stress without negatively affecting the viscosity of the system.
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Affiliation(s)
- Ana Paula Fugolin
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics – Oregon Health & Science University, Portland, OR, US
| | - Ana Rosa Costa
- Department of Restorative Dentistry, Division of Dental Materials – Piracicaba Dental School - UNICAMP, Piracicaba, SP, BRA
| | - Emilie Kono
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics – Oregon Health & Science University, Portland, OR, US
| | - Eleanor Quirk
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics – Oregon Health & Science University, Portland, OR, US
| | - Jack L. Ferracane
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics – Oregon Health & Science University, Portland, OR, US
| | - Carmem S. Pfeifer
- Department of Restorative Dentistry, Division of Biomaterials and Biomechanics – Oregon Health & Science University, Portland, OR, US
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