Nicolae Ghiban,  Cristina Maria Bortun, Ilare Bordeasu, Brândusa  Ghiban,  Nicolae Faur,  Anghel Cernescu, STELA CARMEN HANGANU Evaluation of Mechanical Properties by Stereo-and Scanning Electron Microscopy of Some Heat Curing Dental Resins

Nicolae Ghiban, Cristina Maria Bortun, Ilare Bordeasu, Brândusa Ghiban, Nicolae Faur, Anghel Cernescu, STELA CARMEN HANGANU Evaluation of Mechanical Properties by Stereo-and Scanning Electron Microscopy of Some Heat Curing Dental Resins

Abstract:
Complete dentures technology uses especial heat curing acryllic resins, which are included in DIN EN ISO classification at number 1567, group 1. Polimetacrilates are fragile materials, which fracture easily and often need prosthetic pieces repairs. Evaluation of acryllic resins structural qualities allows choosing of the material with maximum mechanical resistance. Present paper intends to determine some comparative structural studies of three heat curing acryllic resins, concerning behaviour after mechanical testing . There were realized 8 samples from each heat curing resins (Meliodent, Superacryl, and Vertex), using the complete denture technology recommended by the producer. Their mechanical characteristics were determined with help of Zwick Roel equipment. Transversal and longitudinal sections of the fractured zones were evaluated by stereomicroscopy and scanning electron microscopy. Following the mechanical tests, there were obtained the following results: ultimate tensile strength 64 MPa / Meliodent, 66 MPa/ Superacryl, Vertex/ 70MPa; total elongation was 11% for Meliodent, 9% for Superacryl and 5% for Vertex; Young’s elasticity modulus was 4570MPa for Meliodent, 5125 MPa for Supercryl and 6243 MPa for Vertex. By stereomicroscopy there was noticed fragmentation, number of fibres from the transversal cross section, or the aspect, shape, colour of fibre from the matrix. At the scanning electron microscopy, microscopic features may be put in evidence: the aspect of the broken matrix (which is brittle for all the samples), the manner of fracture, the nature of the interface, which is incoherent. Finally the correlation between mechanical behaviour and fracture mechanism was made for dental heat curing resins. Keywords: heat curing acryllic resins, stereomicroscopy, scanning electron microscope

Issue: 2010 Volume 47, Issue 2

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