Evaluation of calcinable cylinders for implant-supported prostheses before and after gas-oxygen flame casting process using conventional and fast mold heating cycles

• Grant number: 09/07266-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2009
• End date: June 30, 2010
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Ricardo Faria Ribeiro
• Grantee: Danilo Zaparolli
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The oral rehabilitation of complete edentulous patients is a great challenge for Dentistry. Throughout the years diverse solutions had been developed in the attempt to reestablish the masticatory and phonetic function and aesthetic of lost teeth. Amongst these solutions the implantation of titanium fixations in the alveolar bones comes in the last few decades being prominence. The osseointegration phenomenon was minutely studied as well as some techniques of prosthetic rehabilitation on osseointegrated implants had been developed and constantly perfected. Innumerable advances of the implantology had propitiated the commercial availability, for some manufacturers, of new size, form and infrastructure materials options, as much for the implants itself how much for the prosthetic components, increasing the possibilities of clinical use and the success possibilities. Several authors suggest that badly suitable prostheses induces overload on the mechanical elements of the system, being able to cause the loss and/or fracture of the gold screws, the abutment screws and even though of the implants. Thus, this lack of adaptation would finish for generating deleterious effect to the biological elements, with the appearance of mucosites, peri-implantites, marginal bone loss and even of the osseointegration. Considering that the casted infrastructure attainment is made in a serie of clinical and laboratory procedures, as impression, waxing, casting, finishing and burnishing, instead of usinability, to get passivity are more complicated. Plastic cylinders are routinely used with the lost wax conventional casting technique, but the problem is that the internal and facing surfaces of the cylinder are directly influenced by the variations of the manual processing, by the casting procedure and the properties of the metallic alloy used. The casting process and the type of investment, with the possibility of using fast heating cycle, considerably diminish the total time for attainment of the casting. In consequence, the objective of this study will be to verify the standardization of the internal dimensions and the adaptation of the prefabricated calcinable cylinders, before and after the gas-oxygen cast flame process. Also the influence of the investment heating cycle (conventional and fast) on the quality of the castings will be analyzed. For verification of the internal standardization of the cylinders before after the casting the silicone replica technique will be used and the adaptation will be verified in an optical microscope, also before and after the casting. (AU)