Effect of chitosan/riboflavin modification on resin/dentin interface: Spectroscopic and microscopic investigations

Abstract

The aim of this study is to investigate the morphological and chemical changes of demineralized dentin collagen-matrix and resin/dentin interface associated with chitosan/riboflavin modification. Dentin disc specimens were prepared from sound molars, acid-etched with 35% phosphoric acid and modified with either 0.1% riboflavin or chitosan/riboflavin (Ch/RF ratios 1:4 or 1:1) and photo-activated by UVA. Morphological and chemical changes associated with surface modification were characterized by SEM and micro-Raman spectroscopy. Dentin surfaces of sound molars were exposed, acid-etched, and modified as described before. Etch-and-rinse dentin adhesive was applied, light-cured, and layered with resin-restorative composite. The resin infiltration and resin/dentin interface were characterized by micro-Raman spectroscopy and SEM. An open-intact collagen network-structure, formation of uniform hybrid-layer and higher resin infiltration were found with 0.1%RF and Ch/RF 1:4 modifications. Raman analysis revealed chemical changes and shifts in Amide bands with the modification of dentin collagen-matrix. The use of riboflavin and chitosan/riboflavin formulations to modify dentin-collagen matrix, with the defined ratios, stabilizes the collagen fibrillar network and enhances resin infiltration and hybrid layer formation. These preliminary results are encouraging for subsequent consideration of chitosan/riboflavin modification in adhesive dentistry.

UVA-activated riboflavin improves the strength of human dentin

“…In the medium and high UVA-RF groups, the amide I and amide III shifts for cross-linked dentin specimens were towards lower and higher frequencies, respectively. This was consistent with previous reports of type-I collagen crosslinking with riboflavin (22). Additionally, the CC pyridine aromatic ring vibration at 1,032 cm -1 , known to be due to the 3-hydroxypyridinium ring which is a crosslinking residue in the collagen (23), showed a notable shift at 1,031 cm -1 in the medium and high UVA-RF groups.…”

Zinc Induces Apatite and Scholzite Formation during Dentin Remineralization

“…Raman spectra evidenced an increase in the area of the organic vibration bands (proline/ hydroxyproline and phenyl) relative to the area of inorganic peaks ( fig. 6 ) [Schwartz et al, 2012;Daood et al, 2013]. Due to the nature of Raman back-scattered spectroscopy, the ratio of mineral signal strength to collagen signal does not indicate the absolute volumetric or mass ratio of mineral to collagen content, but changes in this spectral ratio in organic/inorganic dentin content [Schwartz et al, 2012].…”

Avaliação da Resistência de União Entre Resina Composta e Substrato Dentinário Exposto à Quitosana

“…Em outra situação, na qual a quitosana não foi utilizada isoladamente, verificou-se que sua inserção para a modificação de ácido metacrílico em 16%, posteriormente misturado ao primer de um sistema convencional experimental de três passos resultou na presença de grupos metacrilatos, e por meio de cargas positivas residuais da quitosana houve a união covalentemente ao material restaurador, interagiram eletrostaticamente com a dentina desmineralizada, demonstrando a efetividade da técnica na durabilidade de restaurações dentárias 29 . E considerando os potenciais da riboflavina como agente antioxidante, e da quitosana como agente antibactreriano, estudos demonstraram que em uma proporção de 20% de quitosana em riboflavina, e sua aplicação em dentina previamente aos sistemas adesivos convencionais de três passos, observou-se maior infiltração do adesivo, além da modificação química da matriz colágena, induzindo a maior estabilização da camada hibrida resultante 30 . Considerando a possível ação sinérgica da quitosana, nestas situações, concluiu-se que sua presença melhorou a estabilidade mecânica da dentina desmineralizada contra a degradação hidrolítica ou degeneração colágena, em períodos de ao menos seis meses 31 .…”