The denture teeth and acrylic had worn and now needed to be replaced. The implants were placed in, what was at that time, a common fashion resulting in a bilateral posterior cantilever. She had received five implants in the mandible 23 years prior. This technique should be considered experimental until further studies warrant its use.Ī healthy 63-year-old woman presented with an implant-supported metal-resin hybrid prosthesis. This approach provides support to the cantilevered zirconia to reduce detrimental bending forces. The zirconia suprastructure is bonded to the metal bar with a composite luting resin. This information is then used in the dental laboratory to fabricate a polymethyl methacrylate (PMMA) provisional and, subsequently, a metal substructure and corresponding zirconia shell. A simple in-office workflow allows generation of a master cast and a duplication of the initial implant fixed prosthesis. This article aims to describe a technique for fabrication of a metal-supported zirconia implant fixed prosthesis. This would suggest that it not be used in cantilevered situations to prevent fractures. Zirconia is a ceramic, and like all ceramics, it is stronger in compression then in tension. 29-34 While short-term positive results are reported, most authors suggest to approach this new treatment option cautiously. 28 The most recent development is the use of monolithic zirconia or zirconia veneered with porcelain for fabrication of full-arch implant fixed restorations. Superior fit of CAD/CAM-generated frameworks compared to cast gold frameworks was shown early on. 21-27 The introduction of CAD/CAM has brought about a variety of digitally based production methods. Progress has been made in the production of the metal framework with the introduction of adhesive cylinder luted frameworks, allowing superior passive fit to be attained in a simple analog process. 18-20Ī metal framework is thus needed to support the acrylic and the denture teeth. Fracture rates of immediate loading prostheses of 14% to 88% have been reported. 17 Unfortunately, monolithic acrylic does not reliably function in this capacity over time. 11-16 It was shown that for osseointegration to occur and be maintained, a metal framework was not necessary. With the introduction of immediate loading of freshly placed implants it became common practice to utilize an all-acrylic interim prosthesis. Subsequently, the final restoration was produced. The original protocol called for implants to be submerged for 3 to 6 months after integration, the second phase included abutment connection to the oral cavity. 6-10 Precision fit has, thus, remained an important factor in the production of implant-supported prostheses. 3-5 Such a misfit, however, is directly related to prosthetic problems such as screw loosening. 2 Recent research has shown that a misfit of up to 230 microns does not seem to have negative biological consequences. Because dental implants are rigidly connected to the bone it was deemed necessary to have a passive fit of the prosthesis to the implants to avoid introducing detrimental stresses into the bone-titanium junction. 1 Traditionally, a cast gold framework was used with denture teeth connected with acrylic resin. Brånemark some five decades ago, the restoration of choice was a metal-resin implant fixed full denture, also known as a hybrid prosthesis. With the introduction of dental implants by professor P.I. ![]() The article also highlights the advantages and disadvantages of various materials used for hybrid prostheses. The workflow is discussed, ranging from in-office master cast fabrication to the CAD/CAM production of the provisional and the definitive metal-zirconia prosthesis. This article describes a technique that utilizes a metal substructure to support a chemically and mechanically resin-bonded shell of zirconia. Being a ceramic, zirconia has the potential for fracture. A newer development has centered around the use of monolithic zirconia or zirconia veneered with porcelain. Abstract: The metal-resin hybrid full-arch prosthesis has been a traditionally used type of restoration for full-arch implant fixed dentures.
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