Biochemical Processes at the Interface Composite/ Dental Hard Tissues/ Metal

The structure and the properties of surface (boundary, interfacial) layers at the interface with a solid are important factors determining the properties of bioactive dental composites. Objectives: The purpose of the present study is to evaluate the interface region between composite – dentin; composite – enamel; composite – metal and the biocompatibility of an experimental dental composite. Methods: The materials were composed of a visible light-cured monomer mixture (Bis-GMA + TGDEMA) as a matrix and (gllass with Zn and Ba oxides; colloidal silica) as reinforced filler. Microprobe measurements were carried out with human teeth soaked in artificial saliva (6 month). Cylindrical cavities (3 mm deep, 2 mm in diameter) were selected from prepared teeth following the classical protocol (in oral cavity). Characterization of the experimental dental composite was made by micro- and macro Raman spectral test; micromorphological structure of the interface by SEM; and biological test (ISO- 10993) The biocompatibility was studied using the test of tolerance by the subcutaneous and intramuscular implantation of the cured specimens (Wistar rats) Results: Raman spectra showed that resin molecules were estimated to penetrate 2µm into dentin from the interface. Molecular units in the resin-reinforced dentin were more than in the original monomer solution. In the obtained images, we can observe that all the composites have an homogeneous structure, with a uniform filler distribution in the organic matrix. The composite's adherence to the metal is very good. Conclusion: Raman intensity studies demonstrated the excellent infiltration ability of the monomer into dentine substrate in situ. The SEM analysis provides useful information about many areas of the adhesive-dentin interface. Biological tests lead to the conclusion that the elaborated composites are well tolerated by the organism without any systemic or local rejection manifestation.