Determinación del grado de penetración de cementos de ionómero de vidrio en dentina sana y cariada en molares permanentes

  1. Valverde Rubio, María del Pilar
Supervised by:
  1. Inmaculada Cabello Malagón Director
  2. Clara Serna Muñoz Director

Defence university: Universidad de Murcia

Fecha de defensa: 08 November 2024

Committee:
  1. Yolanda Martínez Beneyto Chair
  2. Francisco Molina Miñano Secretary
  3. Antonio Magán-Fernández Committee member

Type: Thesis

Sustainable development goals

Abstract

INTRODUCTION: The main aim of Minimal Invasive Dentistry (MID) is to preserve as much sound tooth tissue as possible. To this end, strategies for the selective removal of carious dentine have been developed which, together with the use of adhesive and remineralising restorative materials (such as Glass Ionomer Cements- GICs and/or High Viscosity Glass Ionomer Cements-GIC HV), have proven to be effective in halting the progression of carious lesions. However, GICs have disadvantages, such as low mechanical strength and high sensitivity to hydration and dehydration. Composite Resins (CRs), considered the material of choice in restorative dentistry, have no remineralising capacity, but very good mechanical properties. This is why Resin Modified Glass Ionomer Cements (RMGICs), and the new bioactive resins were developed. In addition to the material properties, the clinical success of the restorations lies in their adhesion to tooth tissue, carious dentine being a morphologically and structurally different substrate than sound dentine. Among the material properties, microhardness is one of them, which is strongly determined by the mineral content of the tooth tissue to which the restoration is to be bonded. Confocal Laser Scanning Microscope (CLSM), used with fluorochromes and by cutting the samples into thin slices, is widely used to study the interface between the dental tissue and the restorative material. Evaluation under the Field Emission Scanning Electron Microscope (FESEM) also allows morphological and structural analysis of the interface, as well as Energy Dispersive X-ray Spectroscopy (EDX), with which to determine the composition of the chemical elements of both the dentine and the material. AIM: To study morphologically, chemically and mechanically the interfaces generated by the adhesion of GICs, RMGICs and bioactive resins to sound and carious dentine by means of CLSM and FESEM-EDX, and Vickers surface microhardness. METHODOLOGY: Extracted human permanent molars, 20 sound and 20 with ICDAS 5 occlusal-proximal carious lesions, were used. They were randomly divided into groups according to the restorative material used (I: Riva Light Cure - RMGIC, II: Riva Self Cure HV – GIC HV, III: Activa BioActive Restorative™ - bioactive resin and IV: GrandioSO® - CR, as a control group), the type of dentine substrate (A: sound dentine and B: carious dentine) and the pattern of fluorescein incorporation for microscopic study (a: fluorescein through the pulp chamber and b: fluorescein mixed with the adhesive). In sound teeth, occlusal-proximal cavities were made and in those with carious dentine, selective removal of the carious dentine was performed. Subsequently, the fillings were made with each of the materials, previously mixed with rhodamine B. Finally, each tooth was cut into slices for the study of the interface in CLSM and FESEM-EDX and Vickers microhardness. The study protocol followed the ISO TS 11405 standard and was approved by the Research Ethics Committee of the University of Murcia (ID: CBE 632/2024). The main variables analysed were the ionic concentration and microhardness at the sound and carious material-dentine interfaces, using the Jamovi v 2.3 software. RESULTS: CLSM and FESEM evaluation of the interfacial morphology of groups IAa and IIAa showed adhesion of the cohesively fractured material to dentine. For groups IIIAa, IIIAb and IVAa, IVAb, generally, good interfacial adaptation was observed. Groups IBa and IIBa, showed some differences with sound dentine because there were areas without hybridization, although areas of the interface with material bonded to the carious dentine were also observed. In groups IIIBa, IIIBb and IVBa, IVBb, the opposite happened as in sound dentine, as the separation of the bonding area between material and carious dentine prevailed. In the EDX compositional study, it was observed that the common ions for all the materials were oxygen, carbon, silicon and aluminium, with other minority elements such as fluorine, sodium and calcium, only not present in GrandioSO®; strontium was only present in Riva Light Cure and Riva Self Cure HV, while in Activa BioActive Restorative™ and GrandioSO® it was barium. There were no significant differences in the concentrations of any of the aforementioned ions between Riva Light Cure and Riva Self Cure HV, while there were significant differences between the other materials. According to the materials used, oxygen, calcium, carbon, phosphorus, nitrogen, magnesium, sodium and fluoride were the elements present in sound dentine, with no significant differences for the first four elements. In carious dentine, sulphur, silicon and strontium ions were also found, and there were no significant differences between any of the ions except for fluoride and strontium. In the Vickers microhardness analysis results, there were significant differences between all materials (p<0.001), and also between sound and carious dentine (p=0.005). At the interface level, there were differences within the same materials according to the type of dentine (p>0.001), being always lower in carious dentine, except for Riva Self Cure HV (p=0.605) where it was similar between sound and carious dentine. CONCLUSIONS: The results of this study indicated that, morphologically, the interfaces of sound and carious dentin with GIC HV and RMGIC were similar, with better hybridization in sound dentin than in carious dentin; on the other hand, the bioactive resin had good hybridization in sound dentin, but not in carious dentin. Chemically, the main ions of all materials were mostly coincident, although with difference percentages; the differences between sound and carious dentine were the elements silicon, strontium and sulphur, which were absent in sound dentine. Mechanically, RMGIC performed better in sound dentine, while in carious dentine it was the GIC HV.