Thermal degradation of dentine collagen heated between 100o.C and 300o.C: electron spin resonance, ultraviolet-visible and infrared spectroscopy
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2005
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ENCONTRO NACIONAL DE FISICA DA MATERIA CONDENSADA, 28.
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Resumo
By heating the dentine makes possible to observe loss of water, changes
in collagen conformation, rise of ESR signals and tissue
browning; these changes start at 100OC and are present
up to 300OC, before organic matrix elimination. Some
of the changes were observed reported in the literature
but their origins are not totally understood. In this
work we correlate the changes observed with Electron
Spin Resonance (ESR) spectroscopy, Ultraviolet-Visible
(UV-Vis) and Infrared (IR) spectroscopy clarifying the
chemical origin of all observed results. We analyse heated bovine dentine between 100OC and 300OC with
exposure time of 30 minutes; the samples were cooling down before analysis in the spectrometers. Increasing the heating temperature we observed by infrared
spectroscopy the loss of water (3800-2500 cm−1
) and
conformational change of collagen molecule (fingerprint
region: 1201 cm−1
; 1281 cm−1
; 1234 cm−1 and 1334
cm−1
); all infrared bands decrease linearly with the
temperature. The heated dentine shows ESR signals
that were identified at g values between 2.005 and 2.007
and line width of about 0.8 mT. The ESR intensity increases exponentially with the temperature according
the Arrhenius equation. Over the evaluated temperature range the dentine becomes brown and this colour is
assigned to the optical density (O.D.) increase at ultraviolet and blue spectral range. The O.D. increases with
the temperature, an empirical equation was determined:
O.D.= (103.08/λ)
K, where λ is the wavelength and K is
a constant that change for different temperatures: 3.4
at 100OC, and 10.2 for samples heated at 300OC. The
correlation between infrared absorption bands, rise of
ESR signals and tissue browning was done. The reduction of water was correlated (correlation coefficient (R)
equal 0.85) with the collagen infrared bands; these collagen bands were also correlated with the increase of
ESR signals (R=-0.94) and tissue browning (R=-0.87);
as well as the ESR signals is correlated with tissue browning with R=0.92. This work shows that there is an
association between water loss, collagen conformation,
ESR signals and tissue browning after heating the dentine to temperatures up to 300OC, indicating that all
observed results are assigned to changes in the structure
of collagen molecule.
Como referenciar
BACHMANN, L.; BAFFA, O.; GOMES, A.S.L.; ZEZELL, D.M. Thermal degradation of dentine collagen heated between 100o.C and 300o.C: electron spin resonance, ultraviolet-visible and infrared spectroscopy. In: ENCONTRO NACIONAL DE FISICA DA MATERIA CONDENSADA, 28., 10-14 maio, 2005, Santos, SP. Resumos... p. 215. Disponível em: http://repositorio.ipen.br/handle/123456789/22247. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.