logo 49 | The Camlog Partner Magazine 10 | Science bases, it is of interest to achieve stable constructions that will ideally last for years without complications and aftercare. Temporaries with titanium bases [6] The suitability of titanium bases in temporary restorations was investigated with the question of how different cementation protocols affect the stability of the adhesive bond between titanium bases and temporary abutments made of PMMA. Whereas all bonding surfaces of the titanium bases were blasted with 50-µm Al2O3, the inner surface of the PMMA crowns was treated as follows: a) conditioning with MMA-based liquid (SR Connect, Ivoclar Vivadent), b) blasting with 50-µm Al2O3 and silanizing (Monobond Plus, Ivoclar Vivadent), c) blasting with 30-µm silicate-coated Al2O3 (Rocatec-Plus, 3M ESPE) and additional conditioning with MMA-based liquid (SR Connect) or d) abrasion with 30-µm silica-coated Al2O3 (Rocatec-Plus) and subsequent silanization (Monobond Plus). All samples were cemented with Multilink Hybrid Abutment. Result: variant c), in which the provisional inner surface was blasted and conditioned with a bonding agent, exhibited a higher mean pull-out force of the samples than the other test groups. In terms of retention failures following artificial aging, this group was also slightly better at 83% than the others, each with a 100% retention failure rate. However, in a direct comparison the conventional temporary abutments performed significantly better. Conclusion: It is preferable to select conventional temporary abutments for provisional restorations. When applying PMMA crowns to titanium bases, it is recommended to blast the bonding surfaces of the crown with 30-µm and additionally condition with an MMA-based liquid to provide better retention of the bond. Two-piece components: hybrid abutment crown [7] One option for fabricating a final restoration is to completely extraorally bond a monolithic CAD/CAM fabricated crown directly to a titanium base as a single unit. In a study, the longevity, in other words the stability, of 12 screw-retained restorations each with either lithium disilicate, zirconia or a material consisting of a polymer-infiltrated ceramic network (PICN) was examined. Prior to cementation with Panavia 21 (Kuraray Noritake), the bonding surface of the titanium bases was blasted (50-µm Al2O3) and, in addition, the bonding surfaces of the crowns were pretreated in a material-specific manner: zirconia with blasting (30-µm Al2O3), lithium disilicate and PICN with etching (5% HF). After applying load in the chewing simulator, the following picture emerged: the restorations with lithium disilicate demonstrated no fractures and thus a success rate of 100%. With zirconia, a total of three abutment and one crown fracture were observed (67% success) and in the PICN group, a total of five fractured crowns (58% success). Closer examination of the remaining samples under the microscope revealed loosening in all groups. With 58% complications, the lithium disilicate compounds also performed much better in this respect than the zirconia and PICN compounds with 88% and 86% respectively. In a few PICN crowns, additional cracks were found in the material. Conclusion: The authors concluded that hybrid lithium disilicate abutment crowns can be used for restorations. Zirconia and PICN are less recommended due to their high complication rates. Three-piece components: hybrid abutment and crown [8] The same issue regarding mechanical stability was applied in another study to abutments consisting of a titanium base - meso-abutment - crown, whereby
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