logo 49 | The Camlog Partner Magazine 8 | Science » Study results on the question of which materials for restorations on titanium bases and which pre-treatments of the bonding surfaces allow the greatest possible mechanical stability of implant restorations. Introduction The use of prefabricated titanium adhesive bases as abutments opens up numerous options for the practitioner in the choice of workflow - digital or analog - as well as the materials for the abutments. The advantages of these generally screw-retained restorations are known: the extraoral bonding of the mesostructure and/or the crown allows cement residues to be avoided, the emergence profile can be customized, and the titanium implant-abutment connection allows for secure and wear-free stability [1]. With the majority of CAD/CAM technologies in use today, titanium bases are becoming state-of-the-art in daily practice, particularly for single-tooth restorations. The numbers for this indication have increased markedly in recent years due to the healthy lifestyle and good hygiene of patients as opposed to larger restorations [2]. Due to the digital workflow, patients benefit from an efficient treatment protocol with excellent esthetics, fewer treatment appointments and lower costs [3]. The processing and combination of the various materials, such as titanium and ceramics, often determine the long-term stability of the restoration. The basic rule here is to follow the manufacturer's instructions. However, a variety of products and methods is available on the market for the pretreatment of the bonding surfaces, for cementation and for the suprastructures. Not all appear to be equally suitable and universally applicable. Research at then University of Geneva – Prof. Sailer and Team A research group at the Clinic for Fixed Prosthetics and Biomaterials at the University of Geneva, headed by Professor Irena Sailer, is focusing on the long-term performance of restorations with titanium bases with regard to the choice of crown material and preparation respectively pretreatment of the bonding surfaces. They have published their findings on this subject in several publications over the past three years. Various test setups were used to investigate the mechanical stability and bonding strength between titanium bases and different abutment materials such as zirconia, lithium disilicate and others in the laboratory. The various prosthetic options were also taken into consideration here: the use of the titanium bases as temporary restorations with PMMA and as hybrid abutments or hybrid abutment crowns was also tested. The results show significant differences in some cases and are therefore of valuable use for applications in the dental practice or the laboratory. Insights into five publications of the research group General test setup: thermo-mechanical aging An almost identical test setup, which is also used in a similar form in the industry for the load testing of dental implants (ISO 14801 standard), was selected for each of the five differentiated questions. The test models to be investigated - 12 identically fabricated specimens per test group - each simulating an anterior incisor in the maxilla, were subjected to dynamic loading in the chewing simulator for artificial aging. Analogous to the standard, the implants were embedded with a simulated bone loss of 3 mm and clamped at an angle of 30° to the loading axis. To better replicate the clinical oral environment, the test samples passed through an alternating thermal bath between 5° and 55° for 120 seconds each in parallel to the chewing load. The load exposure lasted over 1,200,000 cycles and reflected a chewing load in practice over a period of approx. five years. After completion of artificial aging, the restorations were examined microscopically. Then, depending on the study question, the retention force of the crown, respectively the bond, was measured by means of a pull-off test, or the bond was statically loaded using a universal testing machine up to mechanical failure and from this the bending moments which cause compressive and tensile stresses in the implant bond were calculated. Single tooth replacement on titanium bases CAD/CAM – stable restorations supported by scientific results SCIENCE Peter Thommen Clinical Research Associate Camlog
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