Fracture resistance of pressable ceramic fused to metal custom implant abutment: An esthetic alternative design
Hernandez Terrazas, Carlos Alberto
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Objectives: The purpose of this study was to determine the feasibility of fabricating a pressable metal ceramic custom implant abutment (Pr) with a full porcelain coverage design, and to compare fracture resistance to its commercially available zirconia counterpart (Zr). Methods: Two groups of implant abutment specimens were fabricated. The experimental group consisted of custom pressed-ceramic (Pr) abutment (n=10), and the control group consisted of CAD/CAM-designed zirconia-based ceramic (Zr) abutment (n=10). For the experimental group, a custom metal abutment was cast using a compatible metal alloy (Lodestar); this was followed by injection molding with leucite reinforced pressable ceramic (IPS InLine Press-over-Metal) around the metal column of the custom implant abutment. For the control group, a specimen was fabricated from CAD/CAM-designed zirconia abutment (Procera Zirconia). Following scanning, all-ceramic crowns with the average dimensions of a human central incisor were fabricated for the experimental and control abutments using lithium disilicate pressable ceramic (IPS e.max Press). Each crown was cemented to the implant abutments with a resin luting agent (Multilink Automix). Samples were subjected to Thermocycling (2000 cycles). Crown-abutment test specimens were fixed to titanium implant analogs and placed in a test stand at 30 degrees from the vertical axis of the specimens in a computer-controlled universal testing device for cyclic loading. After 500,000 cycles samples were statically loaded to failure for further analysis. The independent t test was used to detect if the mean fracture load values between the 2 groups differ significantly (alpha=.05). Results: No samples failed during thermocycling or cyclic loading. The mean fracture load of the experimental group was 1695N (SD=253) during static loading. The control had a mean fracture load of 1277N (SD=242). The mean fracture load of the experimental group was significantly higher than that of the control group; p= 0.0015 (μ Pr >μ Zr ). Conclusions: Within the limitations of this in vitro study, it can be concluded that a fully veneered pressed ceramic fused to metal custom implant abutment can be fabricated and had a higher mean fracture resistance than its commercially available zirconia counterpart over a Nobel Biocare wide implant platform.