Enamel biosynthesis is initiated by the secretion, processing, and self-assembly of a complex mixture of proteins. This supramolecular ensemble controls the nucleation of the crystalline mineral phase. The detection of anisotropic properties by polarizing microscopy has been extensively used to detect macromolecular organizations in ordinary histological sections. The aim of this work was to study the birefringence of enamel organic matrix during the development of rat molar and incisor teeth. Incisor and molar teeth of rats were fixed in 2% paraformaldehyde/0.5% glutaraldehyde in 0.2 M phosphate-buffered saline (PBS), pH 7.2, and decalcified in 5% nitric acid/4% formaldehyde. After paraffin embedding, 5-microm-thick sections were obtained, treated with xylene, and hydrated. Form birefringence curves were obtained after measuring optical retardations in imbibing media, with different refractive indices. Our observations showed that enamel organic matrix of rat incisor and molar teeth is strongly birefringent, presenting an ordered supramolecular structure. The birefringence starts during the early secretion phase and disappears at the maturation phase. The analysis of enamel organic matrix birefringence may be used to detect the effects of genetic and environmental factors on the supramolecular orientation of enamel matrix and their effects on the structure of mature enamel.
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http://dx.doi.org/10.1111/j.1600-0722.2006.00326.x | DOI Listing |
Science
January 2025
Department of Climate Geochemistry, Max Planck Institute for Chemistry, Mainz, Germany.
Incorporation of animal-based foods into early hominin diets has been hypothesized to be a major catalyst of many important evolutionary events, including brain expansion. However, direct evidence of the onset and evolution of animal resource consumption in hominins remains elusive. The nitrogen-15 to nitrogen-14 ratio of collagen provides trophic information about individuals in modern and geologically recent ecosystems (<200,000 years ago), but diagenetic loss of this organic matter precludes studies of greater age.
View Article and Find Full Text PDFScientificWorldJournal
January 2025
Department of Prosthodontics, Indira Gandhi Institute of Dental Sciences, Nellikuzhi, Kothamangalam 686691, Kerala, India.
Dental caries causes mineral loss and organic damage to teeth. Understanding caries and dentin pulp reactions is crucial for effective caries management strategies. There is a lack of knowledge regarding the microscopic and ultramicroscopic changes that occur during caries destruction and reactive changes.
View Article and Find Full Text PDFSci Rep
December 2024
Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, Ecully, UMR5513, 69130, France.
In the context of the oral cavity, an organic layer known as the mucosal pellicle (MP) adheres to the surface of the oral epithelium, playing a pivotal role in lubricating and safeguarding oral tissues. The formation of the MP is driven by interactions between a transmembrane mucin known as MUC1, located on the oral epithelium, and salivary secreted mucin, namely MUC5B and MUC7. This study aimed to investigate the function of MUC1 and the influence of its structure on MP lubrication properties.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Medical and Molecular Biology, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, 19 Jordana St., 41-808 Zabrze, Poland.
Molar incisor hypomineralization (MIH) is a qualitative developmental defect that affects the enamel tissue of permanent molars and can also occur in permanent incisors. Enamel affected by MIH has reduced hardness, increased porosity, and a higher organic content than unaffected enamel. These characteristics predispose the enamel to accumulation of bacteria and a higher prevalence of caries lesions.
View Article and Find Full Text PDFJ Dent
February 2025
Facultad de Ciencias de la Salud, Carrera de Odontologia, Universidad De Los Hemisferios, Quito, Ecuador; Department of Restorative Dentistry, State University of Ponta Grossa, Avenida Carlos Cavalcanti, 4748, Bloco M, Sala 04, Ponta Grossa, Paraná, 84030-900, Brazil. Electronic address:
Objective: This double-blind, split-mouth, randomized equivalence clinical trial aimed to evaluate the 18-month clinical performance of an ormocer-based single-shade resin composite compared with an ormocer-based multi-shade resin composite in non-carious cervical lesions (NCCLs).
Methods: One hundred and twenty restorations were performed on NCCLs with two restorative materials (n = 60): Admira Fusion X-tra resin composite (ormocer-based single-shade), and Admira Fusion resin composite (ormocer-based multi-shade). After rubber dam isolation, a universal adhesive was applied in the selective enamel etching strategy.
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