A COMPARISON OF PASSIVE FIT BETWEEN CONVENTIONAL AND DIGITAL IMPRESSION TECHNIQUES FOR AN ALL-ON-6 MAXILLARY FRAMEWORK

This study compares full-arch superstructure fit via conventional versus digital impressions for passive fit assessment. Six implants were placed in an epoxy cast for parallelism in central, canine, and second premolar areas bilaterally. Two frameworks were made: Group 1 with conventional casted framework using open tray impressions, and Group 2 with milled frameworks via digital impressions. Five frameworks were made in each group.Group 1 involved five splinted open tray conventional impressions for the six implants, leading to a casted superstructure framework. In Group 2, scan bodies were used for digital impressions via an extra-oral scanner, creating 5 milled frameworks using Exocad software.Using the Sheffield test, passive fit was assessed as either passive or non-passive. Gap distance was measured with all implant screws fully tightened and when only the most distal implant was tightened.All frameworks passed the one-screw test for passive fit. Statistically, milled frameworks showed a smaller mean gap value when all implants were fully tightened compared to casted ones. Casted frameworks exhibited higher gap distances (61.74 microns) when all implants were tightened and (146.30 microns) when only implant A was tightened.In conclusion, the milled group demonstrated superior passive fit compared to the casted group in both scenarios: when all implants were fully tightened and specifically when implant (A) was fully tightened, indicating the advantage of digital techniques in ensuring a better passive fit for implant-supported full-arch maxillary frameworks.