Analysis of Photo-initiators in Visible-light-cured Dental Composite Resins

Taira, Masayuki; Urabe, H.; Hirose, Takaaki; Wakasa, K.; Yamaki, M.

doi:10.1177/00220345880670010401

Cited by 139 publications

(86 citation statements)

References 16 publications

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“…The same happened in the study performed by Taira et al where only brands were compared, while the shades tested were not quoted. 29 The results found by these latter authors may seem at odds when compared to the others, since the amount of CQ varied from 0.17 to 1.03 %p/p. However, they calculated the amount of CQ related only to the resinous phase.…”

Section: 29mentioning

confidence: 80%

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Optical characteristics of resin composite before and after polymerization

Eom

Kim

Lee

et al. 2011

J Korean Acad Conserv Dent

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Objectives:The aim of this study was to evaluate the optical characteristics such as color and translucency changes before and after light curing, to quantify the CQ and to measure refractive indices of body and opaque shade of resin composites materials. Materials and Methods: Resin composites used in this study were A2 body and A2 opaque shade of Esthet-X, Filtek supreme, Gradia Direct, Clearfil Majesty and BeautifilⅡ. Color and translucency changes before and after light curing were evaluated by colorimeter, the CQ was quantified by GC-MS and refractive index changes were measured by spectroscopic ellipsometer. Results: Translucency parameter (TP) was significantly increased after curing. The CQ content of body shades are higher than that of opaque shades in all resin composites. Refractive index increased after polymerization in all materials and significant difference in Δrefractive index was found between body and opaque shade (significance level 0.05). Conclusions: For an accurate shade match, direct shade matching of resin composite should be performed by using the cured material. [J Kor Acad Cons Dent 2011;36(3) properties such as color and translucency of the resin composites do not change before and after light curing, direct shade matching can be performed without light curing, resulting in spending less time. Therefore, stability in color and translucency before and after light curing would be an important property in esthetic restorative materials.Resin composite restorations may provide relatively poor color matches, specially a grayish shade is often seen after restoration, which is caused by a projection of the darkness in the oral cavity. From this point of view, the translucency of resin composites must be considered as a critical property just like the color of the material itself. 10,11 The translucency parameter (TP) is the color difference of a material having uniform thickness black and white backings, and corresponds directly to common visual assessments of translucency. 12The composite curing features are strongly influenced by the type and amount of photoinitiators inside.13 Camphorquinone (CQ) is the photosensitizing agent used in most of the brands available on the market. The increase in CQ amount in resin composites leads to a higher level of monomer conversion, improving mechanical and biological properties of these materials.14,15 Studies have shown that there is a limit for the increase of CQ concentration. 16,17 Above this limit the increase in photoinitiator does not benefit the final grade conversion. CQ has the aspect of an intense-yellow-colored powder. Additionally, it has poor photobleaching, which means the yellow color remains the same after light irradiation. Thus, CQ addition turns the material yellowish, making it difficult to be incorporated when lighter shades are desired. 16,18 Most of the organic molecules present in the matrix phase of dental composites and fillers do not effectively transmit visible light. As a result, scattering of light might be considered as...

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Section: 29mentioning

confidence: 80%

“…CQ is featured as an intense yellow powder. 16,18,29,31 Its peculiar color is due to its chromophore; it absorbs light in the region of 470 nm, thus, it reflects a resulting shade ranging between yellow and orange. Some photoinitiators break the chromophore after irradiation, loosing the yellow color, in a process called photobleaching.…”

mentioning

confidence: 99%

Optical characteristics of resin composite before and after polymerization

Eom

Kim

Lee

et al. 2011

J Korean Acad Conserv Dent

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“…2 Photoinitiator, camphorquinone, would be eventually invisible; hence the yellowness of resin composite would be diminished along with an increased blue chroma. 2,3 Even after the completion of polymerization, resin composites undergo further changes in mouth by hydrophilic volumetric changes, Hydrolysis, stains and alteration of surface smoothness. 1,4,5 Overly, determination of color changes may be accomplished with either visual method applying a color shade or quantitavely with a device (e.g.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Different Curing Time Regimens on Immediate Postpolymerization Color Changes of Resin Composites

Mir

Mir²

2012

The Journal of Contemporary Dental Practice

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Aim: Light curing of resin composites may considerably change the color of resin composites. The aim of this study was to evaluate the changing pattern of resin composite's color by different curing times. Results: Color of samples was clinically significant changed by increasing the curing time from 10 to 20s and from 20 to 30s for Clearfil (E = 13.86 and 14.11 respectively,) and Filtek P60 (E = 7.68 and 11.66 respectively). The 'b' component change was responsible for the most color alteration confirmed by the linear regression model (p < 0.001). Conclusion:This study revealed the contrasting pattern of resin composite's color change with the different curing times. Our findings support that light curing is accompanied by a higher attained blue chroma and diminished yellowness of resin composites.Clinical significance: A complete and proper curing of sample resin composites on buccal surface of particular tooth, as a common practice to ensure the maximize concordance composite and tooth color, is reassured according to the considerable differences of undercured and overcured in comparison to normocured composite.

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“…Initiators added to these dimethacrylate monomers mixtures initiate polymerization under a light source producing radicals. In the peculiar case of camphorquinone initiator, co-catalysts such as amines are needed to perform the polymerization [5][6][7]. Organic resins are more often filled (>80w.%) with different types of inorganic fillers like silica, borosilicate glasses, and strontium glasses to improve the resistance of the final composite (rigidity, hardness…).…”

Section: Introductionmentioning

confidence: 99%

Observation of oxygen inhibited layer of organic dental resin by confocal Raman-microscopy

et al. 2012

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Abstract:This study investigated degrees of conversion of oxygen inhibited layer (OIL) of organic dental resins for restoration using Confocal-Raman spectroscopy. The aim was to determine which laser is adapted to determine the degrees of conversion of OIL and to measure variations of thickness and degrees of conversion in OIL with respect to monomers proportions. Bis-GMA (bis-phenol A glycidyl dimethacrylate) and TEGDMA (triethylene glycol dimethacrylate) based resins with various ratio of an equimolecular mixture of camphorquinone/EDMAB (ethyl (4-dimethyl amino) benzoate) were studied with different lasers by confocalRaman spectroscopy. Results show that this technique is adapted for the non destructive measurement of OIL. The Thickness of OIL is not correlated with the proportions of Bis-GMA and TEGDMA in the resin and was close to 3-4µm. Thickness of OIL is very thin without inorganic fillers (3 or 4 µm). Inorganic fillers might be responsible of greater OIL in composite resins.

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Analysis of Photo-initiators in Visible-light-cured Dental Composite Resins

Cited by 139 publications

References 16 publications

Optical characteristics of resin composite before and after polymerization

Optical characteristics of resin composite before and after polymerization

The Effect of Different Curing Time Regimens on Immediate Postpolymerization Color Changes of Resin Composites

Observation of oxygen inhibited layer of organic dental resin by confocal Raman-microscopy

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