Estudio comparativo de la composición y estructura cristalina del esmalte y dentina humano, bovino, ovino y de cerdo

  1. Teruel Fernandez, Juan De Dios
Supervised by:
  1. Antonio José Ortiz Ruiz Director
  2. Ana Hernández Fernández Director

Defence university: Universidad de Murcia

Fecha de defensa: 01 December 2017

Committee:
  1. Gerardo Gómez Moreno Chair
  2. Fabio Camacho Alonso Secretary
  3. Luis Alberto Alcolea Rubio Committee member
Department:
  1. Dermatology, Dentistry, Radiology and Physical Medicine

Type: Thesis

Sustainable development goals

Abstract

Introduction. Human teeth are ideal candidates for conducting in vitro experimental studies. However, their use has many limitations: they are very difficult to obtain with sufficient quality and quantity; it is difficult to establish a homogeneous sample due to the difficulty of controlling the age and origin of the tooth. Therefore, it is necessary to study other alternative substrates. The aim of this research was to study the chemical composition and the differences between the crystalline nanostructures from enamel and dentin of human, bovine, porcine, and ovine species, that are likely candidates for replacing them in studies that test dental material. Material and Methods. 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 mm. Elemental analysis (C/N), thermogravimetric analysis coupled to mass spectrometry (TG-MS), and wavelength dispersive X-ray fluorescence (XRF) were used to analyse the samples' composition. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) were used to analyse the crystalline nanostructures. 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. Hydroxyapatites (HA) in enamel obtained higher crystallinity index (CI)Rietveld than the corresponding dentin of the same species. Human dentin (HD) and human enamel (HE) showed the highest CI, followed by ovine enamel (OE) and ovine dentin (OD). CIFTIR, and enamel crystal sizes were always higher than those of dentin for all species. The greatest CIFTIR were found for HE and OE. The most similar change in heat capacity during the glass transition (?Cp) values to human teeth, were obtained by porcine specimens. To know among all substrates which is closest to the ideal substrate (human tooth), we have used a Multicriterial Decision Making Method (MCDM). Exactly, the Analytical Hierarchic Process (AHP) and the Reference Ideal Method (RIM). Conclusions: C/N, TG-MS and WDXRF have shown that human and bovine enamel and dentine show the greatest similarity among the species analysed. In researches where the physicochemical and mechanical properties of enamel or dentin prevail, ovine teeth should be used as a substitute to human teeth. Where the thermal behavior in an inert atmosphere is more relevant, porcine samples should substitute human teeth. The MDCD indicated that enamel and dentin bovine are the most similar to enamel and dentin human.