Effects of Rehydration on Dentin Strengthened by Heating or UV Irradiation

Hayashi, Mikako; Okamura, Kiyoshi; Koychev, E.V.; Furuya, Yu; Sugeta, Atsushi; Ota, T.; Ebisu, Shigeyuki

doi:10.1177/0022034509354564

Cited by 12 publications

(14 citation statements)

References 21 publications

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“…In a more recent study, Hayashi et al . [53] repeated those studies but then rehydrated the previously dehydrated specimens. These later studies indicate that some, but not all, of the increased flexural strength was lost on rehydration.…”

Section: Discussionmentioning

confidence: 99%

Water distribution in dentin matrices: Bound vs. unbound water

et al. 2015

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Objectives This work measured the amount of bound versus unbound water in completely-demineralized dentin. Methods Dentin beams prepared from extracted human teeth were completely demineralized, rinsed and dried to constant mass. They were rehydrated in 41% relative humidity (RH), while gravimetrically measuring their mass increase until the first plateau was reached at 0.064 (vacuum) or 0.116 g H2O/g dry mass (Drierite). The specimens were then exposed to 60% RH until attaining the second plateau at 0.220 (vacuum) or 0.191 g H2O/g dry mass (Drierite), and subsequently exposed to 99% RH until attaining the third plateau at 0.493 (vacuum) or 0.401 g H2O/g dry mass (Drierite). Results Exposure of the first layer of bound water to 0% RH for 5 min produced a −0.3% loss of bound water; in the second layer of bound water it caused a −3.3% loss of bound water; in the third layer it caused a −6% loss of bound water. Immersion in 100% ethanol or acetone for 5 min produced a 2.8 and 1.9% loss of bound water from the first layer, respectively; it caused a −4 and −7% loss of bound water in the second layer, respectively; and a −17 and −23% loss of bound water in the third layer.. Bound water represented 21–25% of total dentin water. Chemical dehydration of water-saturated dentin with ethanol/acetone for 1 min only removed between 25 to 35% of unbound water, respectively. Significance Attempts to remove bound water by evaporation were not very successful. Chemical dehydration with 100% acetone was more successful than 100% ethanol especially the third layer of bound water. Since unbound water represents between 75–79% of total matrix water, the more such water can be removed, the more resin can be infiltrated.

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Section: Discussionmentioning

confidence: 99%

Water distribution in dentin matrices: Bound vs. unbound water

et al. 2015

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“…Micro-Raman spectroscopy measurements were performed, as reported previously (2,9). Raman spectra were measured using laser Raman microscopy (Renishaw inVia; Renishaw Plc, London, UK).…”

Section: Laser Raman Spectroscopic Analysismentioning

confidence: 99%

“…The laser beam was focused and irradiated onto the specimen with , and the accumulation time was 180 s. The excited Raman scattering light was collected with the same objective lens and guided to the spectrograph, which had a focal length of 500 mm. The Raman spectra obtained was normalized for comparison (2,9). This was done by first reducing the background intensity caused by fluorescence, using an algorithm described previously (10), and then normalizing the spectra to the intensity of the peak at 815 cm -1 , corresponding to the backbone vibration of collagen (11).…”

Section: Laser Raman Spectroscopic Analysismentioning

confidence: 99%

“…Crosslinking (increasing collagen crosslinks), is a means of improving the mechanical properties and molecular stability of collagen-based tissues, such as dentin (2,3). The basic methods for modification of the number of collagen crosslinks can be divided into two types: chemical methods, where various cross-linking solutions such as glutaraldehyde are used (3), and physical methods, using high intensity ultraviolet radiation (2).…”

Section: Introductionmentioning

confidence: 99%

“…The basic methods for modification of the number of collagen crosslinks can be divided into two types: chemical methods, where various cross-linking solutions such as glutaraldehyde are used (3), and physical methods, using high intensity ultraviolet radiation (2). However, the toxic effects of chemical agents limit their application, and the biological safety of high intensity ultraviolet radiation is still uncertain.…”

Section: Introductionmentioning

confidence: 99%

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UVA-activated riboflavin improves the strength of human dentin

Liu

Zhou

Chen

et al. 2015

Journal of Oral Science

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The aim of this study was to evaluate the effects of UVA-activated riboflavin (UVA-RF) on the mechanical properties of non-demineralized human dentin. Dentin specimens obtained from 20 teeth were randomly divided into the following four groups: group 1 (control): no treatment, group 2 (low UVA-RF): specimens were exposed to UVA-RF for 10 min, group 3 (medium UVA-RF): specimens were exposed to UVA-RF for 30 min, and group 4 (high UVA-RF): specimens were exposed to UVA-RF for 60 min. Three-point flexural test and Raman spectroscopic analyses were performed. The mean flexural strengths (MPa) were 129.96, 128.96, 144.21, and 147.54, and the mean elastic modulus (GPa) were 8.59, 8.38, 10.21, and 9.87 for groups 1 to 4, respectively. Raman spectra showed chemical modifications of dental collagen under medium and high UVA-RF treatment. We conclude that medium and high UVA-RF increases the strength of non-demineralized human dentin by collagen crosslinking. (J Oral Sci 57, 229-234, 2015)

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