Browsing by Author "Castellanos, Jaime Eduardo"

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    Estandarización de la técnica de biopsia para determinación de fluoruro en esmalte dental
    (2015) Marín Gallón, Lina María; Castellanos, Jaime Eduardo; Andaló Tenuta, Livia Maria; Martignon Biermann, Stefania; Cury, Jaime Aparecido
    Introduction. Pre-eruptive incorporation of fluoride into dental enamel reflects its systemic exposition during amelogenesis, leading to the use of dental enamel as a biomarker of fluoride exposure. There are not reported studies in Colombia using the enamel biopsy technique, which allows the determination of the fluoride distribution pattern throughout dental enamel. Aim. To standardize the enamel biopsy technique and determine the fluoride content in the enamel of sound unerupted teeth. Methods. With ethical approval and informed consent forms, there were collected 5 third unerupted molar-teeth and of each tooth it were obtained two enamel blocks from the middle third of the crown, in a cross-sectional way. All surfaces were covered with acid-resistant wax leaving the external enamel surface exposed, which were treated with 0.5M HCl for 15, 30, 60, and 120 seconds under constant agitation. Fluoride concentration was determined in each acid extract by means of a fluoride ion-specific electrode and the mass of removed enamel was established (grams) after Pi analyses. The fluoride content in each layer of removed enamel was determined (μg F/g enamel) and in the total of removed enamel (μg F/cm3). Results: There was a fluoride distribution pattern from the surface to the inner enamel, being higher the fluoride concentration in the outer enamel surface (1663.49 ± 266.61 μg F/g enamel). Total fluoride concentration in the total of removed enamel was 1.02 ± 0.25 μg F/cm3. Conclusions: Enamel biopsy technique was standardized. There was found a fluoride distribution pattern from the surface to the inner enamel, similar to the data reported in the literature.
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    Higher Fluorosis Severity Makes Enamel Less Resistant to Demineralization
    (2016) Marín Gallón, Lina María; Cury, Jaime Aparecido; Andaló Tenuta, Livia Maria; Castellanos, Jaime Eduardo; Martignon Biermann, Stefania
    Fluorotic teeth could either be more resistant or more susceptible to the caries process than sound ones due to their higher enamel fluoride concentration and higher porosity (subsurface hypomineralization), respectively; however, there is no consensus on this subject. In this study, a total of 49 human unerupted third molars presenting Thylstrup and Fejerskov (TF) fluorosis scores 0–4 were used. Two enamel slabs were obtained from each tooth. The rest of the tooth crown was powdered, and the enamel was separated from the dentine. In purified powdered enamel, the calcium (Ca), inorganic phosphate (P i ), and fluoride (F) concentrations were determined. The F concentration gradient throughout the enamel and in the enamel, volume was determined in one slab. The other enamel slab was isolated with acid-resistant varnish, subjecting the exposed enamel surface half to a pH-cycling model to evaluate its demineralization resistance and to calculate the demineralization area. The nonexposed surface was used to determine the natural hypomin eralization area found in fluorotic enamel and normalize the demineralization data. The hypomineralization and demineralization areas were assessed by cross-sectional microhardness. For statistical analyses, the data for TF1 and 2, and for TF3 and 4 were pooled. Concentrations of powered enamel Ca and Pi were not significantly different (p > 0.05) among groups TF0, TF1–2 and TF3–4, but a higher F concentration was found in fluorotic enamel (p < 0.05). Highly fluorotic teeth (TF3–4) presented a greater hypomineralization subsurface area and demonstrated lower demineralization resistance than sound enamel (p < 0.05). The findings suggest that a higher severity of fluorosis makes enamel less resistant to the caries process due to its greater subsurface mineral area exposed to demineralization and deeper acid diffusion through the enamel.
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    Identification of proteins from human permanent erupted enamel
    (2015-09) Castiblanco Rubio, Gina Alejandra; Rutishauser, Dorothea; Ilag, Leopold L.; Martignon Biermann, Stefania; Castellanos, Jaime Eduardo; Mejía, Wilson
    Proteins from the extracellular matrix of enamel are highly specific and necessary for proper enamel formation. Most proteins are removed from the matrix by enamel proteases before complete mineralization is achieved; however, some residual protein fragments persist in the mineralized matrix of erupted enamel. So far, only amelogenin peptides obtained by traditional bottom-up proteomics have been recovered and identified in human permanent erupted enamel. In this study, we hypothesize that other enamel-specific proteins are also found in human permanent enamel, by analysing human erupted third molars. Pulverized enamel was used to extract proteins, and the protein extract was subjected directly to liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS) without a previous trypsindigestion step. Amelogenin and non-amelogenin proteins (ameloblastin and enamelin) were succesfully identified. The sequences of the naturally occurring peptides of these proteins are reported, finding in particular that most of the peptides from the amelogenin X-isoform come from the tyrosine-rich amelogenin peptide (TRAP) and that some were identified in all specimens. In conclusion, our LC-MS/MS method without trypsin digestion increased the coverage of identification of the enamel proteome from a few amelogenin peptides to a higher number of peptides from three enamel-specific proteins.