Effect of temperature on the mass and color stability of additional photoinitiatorcontaining composite resins (original) (raw)
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Comparative Effectiveness of Two Light Curing Units on the Properties of Dental Resin Composites
Pakistan Journal of Medicine and Dentistry, 2020
Background: Setting of conventional glass ionomers cement and dental resin composites as filling materials is predominantly through polymerization reaction, which is usually induced by light. The objective of this study was to assess the temperature changes, light intensities, sorption and solubility capability and comparative micro hardness in Dental Resin Composites (DRC) by using two different light curing units that is Quartz Tungsten Halogen (QTH) and Light Emitting Diodes (LED). Methods: This analytical, experimental, in-vitro study was spanned over one month, conducted in the laboratory of Dental Materials, Dr. Ishrat-ul-Ibad Khan Institute of Oral Health Sciences. Through non-probability, convenient sampling, 60 samples of DRCs was prepared as 10mm in diameter and 2mm in thickness in the steel moulds by a single trained operator. Effect of heat generation, light intensities, sorption and solubility and micro hardness during polymerization of DRCs were all measured. Statistica...
Development of a new photoinitiation system for dental light-cure composite resins
Dental Materials, 1999
Objectives: The purpose of this study is to explore the synergistic effect of combining camphorquinone (CQ) with 1-phenyl-1,2-propanedione (PPD) as a new photoinitiator. Methods: A BisGMA, UDMA, TEGDMA monomer mixture was made light-curing with CQ and/or PPD plus 0.2 wt.% N,N-cyanoethylmethylaniline (CEMA). Seventeen groups, three specimens each, were tested in which the concentrations of PPD and CQ were varied. The effect of photosensitizer type (CQ or PPD) and ratio (PPD/CQ) on degree of conversion (DC) was investigated using FTIR spectrophotometry. The results were analyzed by ANOVA and Student-Newman-Keuls' multiple range comparison. The absorption spectra of PPD and CQ were recorded by UV-Vis spectrophotometry. A blind color comparison of specimens containing combinations of the two photosensitizers was also undertaken. Results: Alone, PPD induces a DC which is not significantly different from that of CQ alone. In combination, CQ ϩ PPD produces a DC that generally exceeds that produced by the same concentration of either used alone. The maximum DC occurs between PPD/CQ 1:1 and 1:4. At total photosensitizer concentrations above 1.8 wt.%, DC is increased by PPD but depressed by CQ, which is evidence that different mechanisms are involved. PPD (l max Ϸ 410 nm) and CQ (l max Ϸ 468 nm) have different wavelength absorption ranges, resulting in a perceptibly lighter shade of yellow for PPD. Significance: 1-phenyl-1,2-propanedione is a photosensitizer of potential value in reducing color problems associated with visible light cured dental resins. In combination with camphorquinone, it acts synergistically to produce a more efficient photoinitiation reaction.
Journal of Dentistry, 2013
The aim of this study was to formulate materials with high color stability and reduced degradation by using photoinitiator systems derived from phosphine oxides alternative to the traditional camphorquinone (CQ)/amine system. Methods: Materials were formulated with the monomers BisGMA and TEGDMA as organic matrix. The photoinitiators tested were CQ + amine (EDMAB), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), BAPO + EDMAB, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) and TPO + EDMAB. A 60% mass of silanated glass filler particles was added. Degree of C C conversion was evaluated by Fourier-transformed infrared spectroscopy 10 min after photopolymerization. The color properties were evaluated by a digital spectrophotometer, applying the CIELab parameters, either before photoactivation, immediately after photoactivation, 24 h after dry storage, and one month after water immersion. Water sorption and solubility were assessed by mass gain or loss after storage in water for 30 days. Data were analyzed using ANOVA and Tukey's test (5%). Results: Degree of conversion did not differ statistically among all the tested formulations. Regarding color, only groups with TPO presented satisfactory color stability after one month of water storage (DE < 3.3). Water sorption and water stability did not differ among the groups. Conclusions: Degree of conversion, water sorption and water solubility did not differ among all the tested groups. The TPO-based groups were the only materials with satisfactory color stability after one month of water storage. Clinical significance: The use of a photoinitiator system containing TPO might improve the color stability of resin composites compared with the traditional CQ/amine system while attaining similar physico-chemical properties for the composite.
Examining the Effect of Radiant Exposure on Commercial Photopolimerizable Dental Resin Composites
dentistry journal, 2018
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/cm 2 for 5 s, 1000 mW/cm 2 for 10 s, and 400 mW/cm 2 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/cm 2 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.
Journal of Dentistry, 2015
Coelho.Effect of different photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths.Journal of Dentistry http://dx.ABSTRACT Objectives: To evaluate the effect of photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths. Methods: Model resin-based composites were associated with diphenyl(2,4,6trimethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) or camphorquinone (CQ) associated with 2-(dimethylamino)ethyl methacrylate (DMAEMA), ethyl 4-(dimethyamino)benzoate (EDMAB) or 4-(N,Ndimethylamino)phenethyl alcohol (DMPOH). A narrow (Smartlite, Dentisply) and a broad spectrum (Bluephase G2, Ivoclar Vivadent) LEDs were used for photoactivation (20J/cm 2 ). Fourier transform infrared spectroscopy (FT-IR) was used to evaluate the cure efficiency for each composite, and CIELab parameters to evaluated color stability (∆E 00 ) after aging. The UV-vis absorption spectrophotometric analysis of each photoinitiator and reducing agent was determined. Data were analyzed using two-way ANOVA and Tukey's test for multiple comparisons (α=0.05).
The Photoinitiators Used in Resin Based Dental Composite—A Review and Future Perspectives
Polymers
The presented paper concerns current knowledge of commercial and alternative photoinitiator systems used in dentistry. It discusses alternative and commercial photoinitiators and focuses on mechanisms of polymerization process, in vitro measurement methods and factors influencing the degree of conversion and hardness of dental resins. PubMed, Academia.edu, Google Scholar, Elsevier, ResearchGate and Mendeley, analysis from 1985 to 2020 were searched electronically with appropriate keywords. Over 60 articles were chosen based on relevance to this review. Dental light-cured composites are the most common filling used in dentistry, but every photoinitiator system requires proper light-curing system with suitable spectrum of light. Alternation of photoinitiator might cause changing the values of biomechanical properties such as: degree of conversion, hardness, biocompatibility. This review contains comparison of biomechanical properties of dental composites including different photosensi...
Brazilian Oral Research, 2010
The aim of this study was to observe the influence of two light polymerization units (LED or halogen light) on the degree of conversion (DC) of three dental composites with lighter shades and a different photoinitiator system. The top (T) and bottom (B) surfaces of 60 discs of composite resin (Filtek Supreme, Filtek Z250, Tetric Ceram Bleach) cured either by LED or by halogen lamp (HL) were studied using an FT-Raman spectrometer. The degree of conversion (DC) was evaluated by following the changes in the intensity of the methacrylate C=C stretching mode at 1640 cm -1 . The calculated DC ranged from 54.2% (B) to 73.4% (T) and from 60.2% (B) to 76.6% (T) for the LED and HL, respectively. LED and halogen devices were able to produce an adequate DC for all the resins tested.