Browsing by Subject "Enamel"

Now showing 1 - 5 of 5
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    Biological action of bleaching agents on tooth structure: A review
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2024) Bragança Aragão, Walessa Alana; Santos Chemelo, Victória; de Melo Alencar, Cristiane; Martins Silva, Cecy; Pessanha, Sofia; Reis, Alessandra; de Souza Rodrigues, Renata Duarte; Rodrigues Lima, Rafael
    The use of bleaching agents to remove stains is one of the main dental procedures to improve the aesthetics of teeth. This review presents the main agents used for tooth whitening, existing clinical protocols, and the structural changes that may occur through their use. The main bleaching agents consist of hydrogen peroxide and carbamide peroxide, which are used in bleaching techniques for vital teeth. These techniques can be performed in the office by a professional or by the individual in a home environment under professional guidance. Bleaching agents come in a variety of concentrations and there are over-the-counter products available on the market with lower concentrations of hydrogen peroxide. Due to the chemical characteristics of the agents, changes in the organic and inorganic content of the tooth structure can be observed. These changes are related to morphological changes characterized by increased permeability and surface roughness, such changes compromise the mechanical resistance of the tooth. Furthermore, bleaching agents can promote molecular changes after reaching the dental pulp, resulting in oxidative stress of pulp cells and the release of proinflammatory mediators. Despite the bleaching effectiveness, tooth sensitivity is considered the main side effect of use. Therefore, among the heterogeneity of protocols, those that used the bleaching agent for a prolonged time and in lower concentrations presented more harmful effects on the tooth structure.
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    Comparison of chemical composition of enamel and dentine in human, bovine, porcine and ovine teeth
    (Elsevier, 2015-05) Teruel, Juan de Dios; Alcolea, Alberto; Hernández, Ana; Ortiz Ruiz, Antonio José; Dermatología, Estomatología, Radiología y Medicina Física
    Objective The aim of this paper was to compare the chemical composition of human teeth with other mammal species that are likely candidates for replacing them in studies that test dental material. Design Dentine and enamel fragments extracted from 400 sound human, bovine, porcine and ovine – 100 teeth per species – incisors and molars were mechanically ground up to a final particle size of less than 100 μm. C/N analysis, thermogravimetric analysis coupled to mass spectrometry (TG–MS), and wavelength dispersive X-ray fluorescence (WDXRF) were used to analyse the samples’ composition. Results Elemental analysis showed more organic carbon and nitrogen in dentine than in enamel. Human enamel was the most highly mineralised, with C and N values close to hydroxyapatite. Bovine dentine and enamel were the most similar to human. TG–MS: in all species, enamel contained less carbon and organic matter than dentine. Thermal decomposition of human enamel showed great similarity to synthetic hydroxyapatite, and large differences from bovine, ovine and porcine enamel. Thermal decomposition showed the greatest similarity between human and bovine dentine. WDXRF: Dentine contained larger quantities of Mg, S, Sr and Zn than enamel. Enamel contained larger quantities of P, Ca, Cl, Cu, K and Ca/P ratio than dentine. Human enamel and dentine contained a higher Ca/P ratio, larger quantities of Cl and Cu and lower quantities of Mg, S, Zn than the animal species. Conclusions Elemental analysis, TG–MS and WDXRF have shown that human and bovine enamel and dentine show the greatest similarity among the species analysed.
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    Electron probe microanalysis of permanent human enamel and dentine. A methodological and quantitative study
    (Murcia : F. Hernández, 1998) Sánchez-Quevedo, M.C.; Nieto-Albano, O.H.; García, J.M.; Gómez de Ferraris, M.E.; Campos, Antonio
    Sample preparation of dental tissues for quantitative electron microprobe analysis has not been critically examined because of the highly mineralized nature of these structures. The present study was designed to establish the most suitable method for the electron probe quantitative determination of calcium in human permanent enamel and dentine while preserving the morphological features. Comparisons of quantitative data obtained with air-drying and freeze-drying methods showed that calcium in enamel was more accurately measured in specimens prepared with cryopreservation and freeze-drying. No significant differences between the methods tested were found in dentine although cryopreservation and freeze-drying yielded less statistical variability. Moreover this approach did not modify morphological features of interest. We recommend this combination of processing techniques f o r human permanent teeth not only because it was found the most accurate and least variable in determining calcium concentration, but also because of its potential usefulness in studies of alterations in tooth mineralization.
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    Influence of fluoride varnish application on enamel adhesion of a universal adhesive
    (Quintessence Publishing, 2021-01) Ortiz Ruiz, Antonio José; Martínez Marco, Francisco José; Pérez Silva, Amparo; Serna Muñoz, Clara; Cabello, Inmaculada; Banerjee, Avijit; Dermatología, Estomatología, Radiología y Medicina Física
    Purpose: To study the effect of the varnish type, application time and surface polishing on the shear bond strength (SBS) of a universal adhesive in healthy and demineralized bovine enamel. Materials and Methods: 432 bovine primary central incisors were assigned to 18 groups according to enamel mineralization [healthy and demineralized], topical varnish [Clinpro White Varnish (CWV; 3M Oral Care) and Profluorid (PFV, Voco)], remineralization time [24 h or 21 days] and polishing or not of the enamel surface. Adhesion was tested using Futurabond M (Voco)+ and GrandioSO (Voco). Sheer bond strength (SBS) was measured and the fracture mode studied. The statistical analysis was performed using two-way ANOVA, Tukey's test, and Pearson's chi-squared test. Results: In healthy bovine enamel, CWV reduced SBS at 24 h and 21 days; polishing significantly improved SBS. PFV increased SBS in healthy enamel at 21 days and demineralized enamel at 24 h and 21 days; polishing had no effect on SBS. The application time and polishing of the enamel surface affected the behavior of varnishes with respect to SBS. There was a correlation between the type of fracture and the degree of mineralization as well as the timepoint of varnish application. Conclusions: Remineralization of demineralized enamel with fluoride varnishes permits the recovery of the bond strength obtained in healthy enamel. Of the two varnishes studied, PFV had the highest SBS and more uniform behavior, regardless of the application timepoint, degree of mineralization, and surface treatment of the enamel.
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    Structural differences in enamel and dentin in human, bovine, porcine, and ovine teeth
    (Elsevier, 2018-03) Ortiz Ruiz, Antonio José; Teruel Fernández, Juan de Dios; Alcolea Rubio, Luis Alberto; Hernández Fernández, Ana; Martínez Beneyto, Yolanda; Gispert Guirado, Francesc; Dermatología, Estomatología, Radiología y Medicina Física
    Background The aim was to study differences between crystalline nanostructures from the enamel and dentin of human, bovine, porcine, and ovine species. Methods Dentine and enamel fragments extracted from sound human, bovine, porcine and ovine incisors and molars were mechanically ground up to a final particle size of <100 μm. Samples were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Results Human enamel (HE) and dentin (HD) showed a-axis and c-axis lengths of the carbonate apatite (CAP) crystal lattice nearer to synthetic hydroxyapatite (SHA), which had the smallest size. Enamel crystal sizes were always higher than those of dentin for all species. HE and HD had the largest crystal, followed by bovine samples. Hydroxyapatites (HAs) in enamel had a higher crystallinity index (CI), CIRietveld and CIFTIR, than the corresponding dentin of the same species. HE and HD had the highest CIs, followed by ovine enamel (OE). The changes in heat capacity that were nearest to values in human teeth during the glass transition (ΔCp) were in porcine specimens. There was a significant direct correlation between the size of the a-axis and the substitution by both type A and B carbonates. The size of the nanocrystals and the crystallinity (CIRietveld y CIFTIR) were significantly and negatively correlated with the proteic phase of all the substrates. There was a strongly positive correlation between the caloric capacity, the CIs and the crystal size and a strongly negative correlation between carbonates type A and B and proteins. Conclusions There are differences in the organic and inorganic content of human, bovine, porcine and ovine enamels and dentins which should be taken into account when interpreting the results of studies using animal substrates as substitutes for human material.