|Tipo di tesi||Tesi di dottorato di ricerca|
|Titolo||Framework in Protesi Fissa: progettazione e trattamento di superficie|
|Titolo in inglese||Framework in Fixed Prosthodontics: design and surface treatment|
|Settore scientifico disciplinare||MED/28 - MALATTIE ODONTOSTOMATOLOGICHE|
|Corso di studi||Scuola di D.R. in HIGH MECHANICS AND AUTOMOTIVE DESIGN & TECHNOLOGY / MECCANICA AVANZATA E TECNICA DEL VEICOLO|
|Data inizio appello||2015-03-24|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
INTRODUZIONE: La Y-TZP è il materiale ceramico di elezione per la realizzazione di framework di Protesi Fissa. La progettazione del framework assume fondamentale importanza perché incide in modo determinante sul successo di lungo termine delle riabilitazioni di Protesi Fissa tradizionale ed implantare. La progettazione del framework si lega alle caratteristiche intrinseche del materiale che si decide di impiegare per la riabilitazione. La Y-TZP viene sottoposta ad un processo di lucidatura necessario per diminuire i livelli di Rugosità di Superficie (Ra). La Ra è un parametro fondamentale che amplifica il processo di adesione batterica e incide in modo significativo sul grado di usura dello smalto dei denti antagonisti a riabilitazioni protesiche in Y-TZP.
INTRODUCTION: The Y-TZP ceramic is the material of choice for the construction of frameworks in Fixed Prosthesis. The design of the framework is of fundamental importance because it has a crucial effect on the long-term success of the rehabilitation of traditional Fixed Prosthodontics and Implant. The design of the framework is linked to the intrinsic characteristics of the material that you decide to use for rehabilitation. The Y-TZP is subjected to a polishing process, necessary to decrease levels of surface roughness (Ra). The Ra is a fundamental parameter that amplifys the process of bacterial adhesion and has a significant impact on the degree of wear of tooth enamel antagonists in prosthetic rehabilitation in Y-TZP. OBJECTIVES: The experimental study proposes these objectives: 1) Design framework of Fixed Prosthetics in Y-TZP that is able to guarantee function and durability 2) Protocol polishing of Y-TZP that is able to obtain values of Ra that minimize bacterial adhesion and wear of the tooth enamel. MATERIALS AND METHODS: The design of the framework of Fixed Prosthodontics is conducted with a Finite Element Study on the basis of the mechanical properties of flexural strength of Y-TZP. The data of flexural strength were obtained with in vitro tests of resistance according to ASTM C 1161 (for advanced ceramic materials) evidencing the actual mechanical properties of Y-TZP. In Finite Element Study have been studied various geometries of prosthetic framework in Y-TZP to build diagrams for the design of the connection between abutments and cantilever. The Study was conducted by discretizing the framework prosthetic and simulating the support natural teeth through a layer of elements that simulate the missing part. To identify the protocol of polishing of Y-TZP were made 21 samples consisting of platelets of Y-TZP of dimensions 1 cm by 0.7 cm and a constant thickness of 1 mm. Platelets were obtained by means of a drive CAM 4-axis that provides for the milling of blocks in a pre-sintered and the subsequent sintering in a furnace at temperatures of 1500-1700 ° C. The samples were subjected to 5 protocols polishing by 5 different operators in order to obtain 5 groups of 4 samples each. A sample of zirconium oxide not subjected to polishing has been chosen as the control group. The surface roughness (Ra, uM) of each sample polished and the starting sample (CP) was evaluated by surface roughness tester Hommer-T 2000 with inductive position transducer. Analyzes were performed using morphological SEM XL30 scanning electron microscope to analyze the surface morphology of the sample of each group with the lowest values of Ra and CP of the sample. RESULTS: The design of the framework in Y-TZP in terms of size results similar to traditional metal framework. Polishing techniques tested have led to a significant reduction of the values of Ra of the surface of the zirconia compared to the starting sample. However, not all techniques have proved to be equally effective in reducing the degree of Ra. CONCLUSIONS: The Y-TZP lets to design framework of Fixed Prosthodontics using connectors of similar size to the traditional fixed prostheses with metal framework. The Y-TZP ensures small size of the framework and suitable sanitary spaces without sacrificing reliability in terms of resistance. A proper protocol polishing Y-TZP must provide a first phase with diamond rotary instruments and a second phase with diamond paste.