IADR Abstract Archives
Effect of Recent Model Fabrication Techniques on Passivity of Fit
Objectives: This in vitro study was designed to evaluate different model fabrication techniques; 3D printed casts, CAD/CAM milled casts and conventional stone cast, on the passivity of fit for Implant supported FDP.
Methods: A master model simulating a clinical case with missing lower first mandibular molar was fabricated from epoxy resin having 2 implants placed in the lower second premolar and the lower second molar region, from which an optical impression was made to fabricate a 3D printed model and a milled model using STL file. PVS impression was done to fabricate a conventional cast. Upon these three casts, five three units monolithic Zirconia bridges were fabricated on each group (n=5) after optical impression and milling to assess the passivity of fit using strain gauge attached mesially and distally to premolar and molar regions, Data were presented as median and interquartile range, the mean and median values were calculated using Kolmogorov-Smirnov andShapiro-Wilk tests.
Results: The mean absolute strain development at the different strain gauge position ranged from 5µm/m to 275µm/m. Generally the molar channels (mesial and distal) showed less strain values compared to the premolar channels (mesial and distal). The 3D printed models showed strain values in the distal premolar area and the mesial molar area higher than the mesial premolar and distal molar areas. The conventional models showed the highest strain values in distal premolar area. The milled model showed high strain values in all channels except in the distal molar area. In the overall channel comparison, the conventional cast showed the highest values of strain followed by the milled cast and then the 3D printed cast, However the difference were statistically insignificant.
Conclusions: 3D printed models can be used in fixed dental prosthesis fabrication with favourable effect on passivity of fit.
Methods: A master model simulating a clinical case with missing lower first mandibular molar was fabricated from epoxy resin having 2 implants placed in the lower second premolar and the lower second molar region, from which an optical impression was made to fabricate a 3D printed model and a milled model using STL file. PVS impression was done to fabricate a conventional cast. Upon these three casts, five three units monolithic Zirconia bridges were fabricated on each group (n=5) after optical impression and milling to assess the passivity of fit using strain gauge attached mesially and distally to premolar and molar regions, Data were presented as median and interquartile range, the mean and median values were calculated using Kolmogorov-Smirnov andShapiro-Wilk tests.
Results: The mean absolute strain development at the different strain gauge position ranged from 5µm/m to 275µm/m. Generally the molar channels (mesial and distal) showed less strain values compared to the premolar channels (mesial and distal). The 3D printed models showed strain values in the distal premolar area and the mesial molar area higher than the mesial premolar and distal molar areas. The conventional models showed the highest strain values in distal premolar area. The milled model showed high strain values in all channels except in the distal molar area. In the overall channel comparison, the conventional cast showed the highest values of strain followed by the milled cast and then the 3D printed cast, However the difference were statistically insignificant.
Conclusions: 3D printed models can be used in fixed dental prosthesis fabrication with favourable effect on passivity of fit.
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