Zirconia implant-supported prosthesis: updates on materials, technologies and design / Implanto-protesi in zirconia: aggiornamenti su materiali, tecnologie e progettazione

OBJECTIVES The aim of this study is to provide an updated overview of the types of zirconia, manufacturing technologies and implant -prosthetic designs applicable to implantsupported full -arch rehabilitations based on the data currently available on the topic. MATERIALS AND METHODS The search was conducted using the PubMed/Medline database. The inclusion criteria led to the analysis of all the material selected through the combination of the following key terms: "zirconia" AND "full -arch" OR "complete -arch" AND "implant supported prostheses" OR "implant supported restorations" OR "implant supported rehabilitations"; "zirconia" AND "dental materials"; "zirconia" AND "dental applications"; "zirconia" AND "manufacturing technologies". The exclusion criteria do not allow the examination of case reports, reviews and works that do not focus on the evolution of zirconia, manufacturing technologies and implant -prosthetic design. Only studies in English were examined. RESULTS The recent evolution of zirconia-based materials is aimed at an effective compromise between esthetic and mechanical properties. Monolithic multilayer zirconia represents the latest evolution, introduced in an attempt to imitate the characteristics of the natural tooth. These materials together with modern zirconia manufacturing and sintering technologies are promising but, to date, lack of data on indications and protocols for use. The available data shows that, currently, second generation zirconia is the reference material for the creation of screw -retained implant -supported rehabilitations and represents a promising alternative to traditional solutions. Newer materials such as 4Y-TZP and multilayer zirconia represent potential alternatives that require dedicated clinical studies. Equally, modern sintering technologies such as microwave technology require further in vitro and clinical data to be validated in complex implant -supported frameworks. A modern design alternative is represented by the hybrid titanium-zirconia implant prosthesis with the first short-term data. This design includes a titanium bar supporting a latest generation zirconia superstructure. CONCLUSIONS Monolithic screw -retained rehabilitations in 3Y-TZP of second generation made with subtractive technology and conventional sintering currently represent the most predictable zirconia prosthesis from a prognostic point of view and with the most encouraging data in the literature. More recent materials and manufacturing technologies represent potential alternatives that require dedicated clinical studies. In this clinical scenario, alternative implant -prosthetic designs such as hybrid zirconia-titanium rehabilitation seem promising solutions that are well suited to the characteristics of the latest generation zirconia. CLINICAL SIGNIFICANCE Full -arch implant -supported rehabilitation in zirconia today can be achieved with a monolithic zirconia implant -prosthetic design or with an alternative hybrid solution that includes a titanium substructure and a monolithic zirconia superstructure. The prosthetic success of both of these solutions is linked to correct technical and manufacturing choices which have as a non-negotiable prerequisite the perfect knowledge of zirconia-based materials.