Browsing by Subject "Dentin"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Open Access
    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.
  • Thumbnail Image
    Publication
    Open Access
    Determination of the degree of penetration of glass ionomer cements in the healthy and decayed dentine of permanent molars
    (MDPI, 2025-08-25) Valverde Rubio, Pilar; Cereceda Villaescusa, Pilar; Cabello, Inmaculada; Poza Pascual, Andrea; Ortiz Ruiz, Antonio José; Serna Muñoz, Clara; Dermatología, Estomatología, Radiología y Medicina Física; Facultad de Medicina
    This study aimed to evaluate the penetration and bonding performance of three restorative materials—high-viscosity glass ionomer cement (Riva Self Cure HV), resin-modified glass ionomer cement (Riva Light Cure) and a bioactive resin (Activa BioActive Restorative™)—in the healthy and carious dentine of permanent molars. Forty extracted human molars with sound or decayed dentine were restored following standardised protocols and subsequently divided into slices. So, twenty-four samples were used for each group (sound and carious dentine) for interface analysis using confocal laser scanning microscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, and another eight simples were used for each group (sound and carious dentine) for Vickers microhardness testing. Results showed that both glass ionomer cements achieved consistent chemical bonding in healthy dentine and demonstrated better interfacial adaptation compared to carious dentine, where partially demineralised areas showed weaker bonding. The bioactive resin exhibited good adhesion in sound dentine due to the adhesive system but showed poorer interaction in decayed dentine with signs of interfacial separation. Elemental analysis revealed similar compositions among materials, with no significant differences in material concentrations among the ionomers, while there were significant differences with the other materials. On the other hand, some variations were observed in the sulphur, fluoride and strontium content depending on dentine condition. Microhardness values were higher in healthy dentine than in carious dentine for all materials (p < 0.001), except the high-viscosity glass ionomer, which maintained stable hardness in both substrates (36.33 ± 6.23 VHN vs. 34.56 ± 4.31 VHN; p = 0.605). These findings highlight the relevance of material selection and dentine condition in minimally invasive restorative dentistry.
  • Thumbnail Image
    Publication
    Restricted
    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.