Studies on optical properties of two commercial visible‐light‐cured composite resins by diffuse reflectance measurements

Taira, Masayuki; Okazaki, Masanori; Takahashi, Junji

doi:10.1046/j.1365-2842.1999.00378.x

Cited by 31 publications

(36 citation statements)

References 14 publications

(20 reference statements)

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“…6a), caused by the presence of the polymerization initiator (camphorquinone). The reported depth of blue light penetration normally does not exceed 2-3 mm [21] which limits the depth of cure. However, for the NIR region, experiments did not show any strong absorption peaks, therefore, allowing efficient penetration of the light through the sample.…”

Section: Discussionmentioning

confidence: 99%

Use of NIR light and upconversion phosphors in light-curable polymers

et al. 2012

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OBJECTIVE: Light-curable polymers are commonly used in restorative surgery, prosthodontics and surgical procedures. Despite the fact of wide application, there are clinical problems due to limitations of blue light penetration: application is restricted to defects exposed to the light source, layered filling of defect is required. METHODS: Combining photo-activation and up conversion allows efficient polymer hardening by deep penetrating near-infrared (NIR) light. The prerequisite 450 nm blue light to polymerize dental resins could be achieved by filler particles, which absorb the incident NIR irradiation and convert it into visible light. RESULTS: The on spot generated blue light results in uniform polymer hardening. Composite samples of 5mm thickness were cured two times faster than pure polymer cured by blue light (30 and 60 s, respectively). Overall degree of monomer conversion resulted in higher values of more than 40%. The enhanced transmission of NIR light was confirmed by optical analysis of dentin and enamel. The NIR transmittance surge in the 800-1200 nm window could improve sealing of complex and deep caries lesions. SIGNIFICANCE: We demonstrate faster curing and an improved degree of polymerization by using upconversion filler particles as multiple light emission centers. This study represents an alternative approach in curing dental resins by NIR source. AbstractObjective. Light-curable polymers are commonly used in restorative surgery, prosthodontics and surgical procedures. Despite the fact of wide application, there are clinical problems due to limitations of blue light penetration: application is restricted to defects exposed to the light source, layered filling of defect is required.Methods. Combining photo-activation and up-conversion allows efficient polymer hardening by deep penetrating NIR light. The prerequisite 450 nm blue light to polymerize dental resins could be achieved by filler particles, which absorb the incident NIR irradiation and convert it into visible light.Results. The on spot generated blue light results in uniform polymer hardening.Composite samples of 5 mm thickness were cured two times faster than pure polymer cured by blue light (30 and 60 sec, respectively). Overall degree of monomer conversion resulted in higher values of more than 40 %. The enhanced transmission of NIR light was confirmed by optical analysis of dentine and enamel. The NIR transmittance surge in the 800÷1200 nm window could improve sealing of complex and deep caries lesions.Significance. We demonstrate faster curing and an improved degree of polymerization by using upconversion filler particles as multiple light emission centers. This study represents an alternative approach in curing dental resins by NIR source.3

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Section: Discussionmentioning

confidence: 99%

Use of NIR light and upconversion phosphors in light-curable polymers

et al. 2012

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“…This alteration reflects the increase of refractive index of the resin phase associated with monomer conversion (into polymer) of monomer mixtures, while refractive index of the filler remains unchanged. 17 In the present study, diffuse reflectance is correlated with the L* value, and the measured reflectance was varied by the measuring geometry and the aperture size. L* value decreased after polymerization except SYC.…”

Section: Discussionmentioning

confidence: 99%

Difference in polymerization color changes of dental resin composites by the measuring aperture size

2003

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The objective of this study was to evaluate the influence of the illuminating/viewing aperture diameter of 11 mm/8 mm and 3 mm/3 mm and measuring geometry on the color and polymerization color changes of dental resin composites. Color of resin composites of 12 mm in diameter was measured on a reflection spectrophotometer with SCE and SCI geometry under D65 illumination. Before polymerization, difference in the three-color coordinates by the material was prominent in spite of the fact that the shade designation of all materials was the same. After polymerization, L* value decreased in hybrid composites but not in packable composites, and changes in a* value were small. When the same aperture size was used, polymerization color change with the SCE was generally higher than those with the SCI. Measured color was different by the aperture size, and the color difference was 16.82-27.05 before polymerization and 20.09-28.51 after polymerization. General trends of polymerization color change were similar in both aperture sizes. Polymerization color changes with 3-mm aperture size were higher than those with 8-mm aperture size in hybrid resin composites in both geometries (p < 0.05); however, the color change was material dependent in the case of packable resin composites.

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“…Once an acceptable match is obtained, the color match should ideally be maintained after polymerization. However, the optical properties of dental composite resins change because of polymerization, and the extent of change is influenced by the brand and shade of resin composites and the wavelength of curing lights 4,5) . Uchida et al 6) also reported that ultraviolet light exposure induced physico-chemical reactions in composite resins, such that lighter shades of composites were likely to be subject to higher color degradation through environmental effects of sunlight exposure.…”

Section: Introductionmentioning

confidence: 99%

Effects of different polishing methods on color stability of resin composites after accelerated aging

et al. 2013

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The purpose of this study was to evaluate the effect of polishing procedures on the color stability of different types of composites after aging. Forty disk-shaped specimens (Ø10×2 mm) were prepared for each composite resin type (an ormocer, a packable, a nanohybrid, and a microhybrid) for a total of 160 specimens. Each composite group was divided into four subgroups according to polishing method (n=10): control (no finishing and polishing), polishing disk, polishing wheel, and glaze material. Color parameters (L*, a*, and b*) and surface roughness were measured before and after accelerated aging. Of the polishing methods, glazed specimens showed the lowest color change (∆E*), ∆L*, and ∆b* values (p<0.05). Of the composite resins, the microhybrid composite showed the lowest ∆E* value, whereas the ormocer showed the highest (p<0.05). For all composite types, the surface roughness of their control groups decreased after aging (p<0.05). In conclusion, all composite resins showed color changes after accelerated aging, with the use of glaze material resulting in the lowest color change.

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Studies on optical properties of two commercial visible‐light‐cured composite resins by diffuse reflectance measurements

Cited by 31 publications

References 14 publications

Use of NIR light and upconversion phosphors in light-curable polymers

Use of NIR light and upconversion phosphors in light-curable polymers

Difference in polymerization color changes of dental resin composites by the measuring aperture size

Effects of different polishing methods on color stability of resin composites after accelerated aging

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