Contemporary clinical and technological aspects of the metal carcasses of fixed dentures

Abstract

Introduction. The development of technology forces us to analyze the manufacturing techniques we use daily. Thus, classical manufacturing techniques are increasingly being replaced by automated production systems that optimize the quality and accuracy of finished work. Initially, the casting technique was based on gold alloys, which were replaced by alloys such as nickelchromium (Ni-Cr) and cobalt-chromium (Co-Cr). In the last decade, new manufacturing processes using computer-aided design / computer-aided manufacturing (CAD / CAM) are becoming increasingly important for producing biomedical devices and dental prostheses. Co-Cr alloy dental carcasses can be manufactured using two technologies based on CAD / CAM processing: substrate manufacturing and addition manufacturing. Aim of the study. Comparative evaluation of contemporary technological processes in order to optimize the use of fixed dental prosthesis with metal casing. Materials and methods. The present work is based on the results of the complex clinical, paraclinical and prosthetic treatment with fixed works of 10 patients (6 m., 4 w.) and the analysis of the ambulatory files of 50 patients (32 m., 18 w.) with the age between 35 and 65 years, with different types of edentation. Selection of patients included: patients with severe systemic disease, patients with dental injuries coronary patients with fixed dentures, partial edentation patients with different classes according to Kennedy of maxilla and mandible, patients with financial means. In order to study comparatively different metal carcass manufacturing technologies, a Geller study model was developed, the metal mobilizable bin being standard. On this metallic shroud the metal carcass was made by three techniques (casting, milling and SLM). The obtained metal carcasses have been scanned and studied electronically in order to obtain objective data on the comparative accuracy of metallic constructions. Results. According to the data obtained at the end of the study it was found that following scanning and electronic measurements, we obtained the following data: the size of the standard bin V-O 8,435 mm M-D 6,752 mm. Metal frames were made and the internal part measured by casting method the V-O 8,545mm M-D 6,944mm; by SLM printing method V-O 8,305 mm M-D 6,702 mm; by milling method V-O 8,438 mm M-D 6,748 mm. Conclusions. Following the study and obtaining the electronic measurements of all Co-Cr alloy metal carcasses in order to make the fixed works by various manufacturing techniques (casting, milling and SLM) it was proved that all the techniques fall within the clinically acceptable range (<120 μm). The automated metal carcassing system is more precise than the classic technique, which motivate us to switch to automated dental prostheses.