logo 49 | The Camlog Partner Magazine Science| 11 the individual mesostructure was made of zirconia. The crowns were milled from either lithium disilicate, zirconia or PICN. The bonds were pretreated in a material-specific manner analogous to the above test. The inner and outer surfaces of the meso-abutments were also blasted (30-µm) and the parts were cemented finally with Panavia 21. In this test setup, the samples of all groups survived the chewing simulation and no fractures or adhesive failures were observed. In the subsequent fracture test, all constructions fractured at the same point, namely with a fracture of the abutment screw in the implant. Further evaluation showed that the titanium-zirconia-zirconia connection resulted in the highest and statistically significant flexural moment in comparison and, in addition, exhibited no other failure patterns, such as cracks in the crown. Lithium disilicate and PICN crowns, on the other hand, exhibited small cracks after the fracture test, but these could have been test-related. Conclusion: This study showed that all tested material combinations of crowns in combination with zirconia meso-abutments on titanium bases could possibly successfully withstand the load in the mouth. In this respect, the choice of material for the crown would appear to be secondary in this indication. Summary Titanium bases are suitable for esthetic and durable single-tooth restorations. Stable restorations which can withstand the chewing load can be fabricated in laboratory work by applying specific pretreatments to the bonding surfaces. The results of the research group in Geneva can be utilized as recommendations for this purpose. However, the mechanical tests cannot accurately reproduce the performance in everyday clinical practice and still need to be confirmed by longterm clinical data. Professor Sailer's group continues its work on this topic and will be publishing further papers, for example on the type of bonding. [1] Fischer C, Gehrke P. Taktische Einheit: CAD/CAM-Hybridabutments. Quintessenz Zahntech 2017;43(11):1526-1542. [2] Graf T, Mielke J, Brandt S, Stimmelmayr M, Güth JF. CAD/ CAM-gefertigter Einzelzahnersatz auf Implantaten: Was ist möglich, sinnvoll und effizient? Eine Übersicht. Implantologie 2021;29(3):285-299. [3] Hermann F. Der volldigitale Chairside-Workflow in der Implantologie. Digital ist effizient. Teamwork 2017;3:1-12 [4] Pitta J, Burkhardt F, Mekki M, Fehmer V, Mojon P, Sailer I. Effect of airborne-particle abrasion of a titanium base abutment on the stability of the bonded interface and retention forces of crowns after artificial aging. J Prosthet Dent 2021;126:214-21. https://pubmed.ncbi.nlm.nih.gov/32921422/ [5] Burkhardt F, Pitta J, Fehmer V, Mojon P, Sailer I. Retention forces of monolithic CAD/CAM crowns adhesively cemented to titanium base abutments – effect of saliva contamination followed by cleaning of the titanium bond surface. Materials 2021;14(12):3375. https://pubmed.ncbi.nlm.nih. gov/34207110/ [6] Pitta J, Bijelic-Donova J, Burkhardt F, Närhi T, Sailer I. Temporary implant-supported single crowns using titanium base abutments: an in vitro study on bonding stability and pullout forces. Int J Prosthodont; 2020;33:546-552. https://pubmed.ncbi.nlm.nih.gov/32956436/ [7] Pitta J, Hjerppe J, Burkhardt F, Fehmer V, Mojon P, Sailer I. Mechanical stability and technical outcomes of monolithic CAD/CAM fabricated abutment-crowns supported by titanium bases: an in vitro study. Clin Oral Implants Res 2021;32(2):222-232. https://pubmed.ncbi.nlm.nih.gov/33258267/ [8] Pitta J, Hicklin SP, Fehmer V, Boldt J, Gierthmuehlen PC, Sailer I. Mechanical stability of zirconia meso-abutments bonded to titanium bases restored with different monolithic all-ceramic crowns. Int J Oral Maxillofac Implants 2019;34:1091-1097. https://pubmed.ncbi.nlm.nih.gov/30934031/ Literature
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