REMOVABLE OVERDENTURE VERSUS FIXED BRIDGE FABRICATED ON “ALL-ON-4” IMPLANTS USING CAD/CAM TECHNOLOGY (Strain Gauge Analysis)

Abstract

This in-vitro study was conducted to compare stresses induced on distal implants in All-On-4® concept, between digitally constructed removable overdenture and fixed bridge (fixed-detachable prosthesis), using strain gauge analysis. This study was conducted using a 3D model simulating a completely edentulous maxillary arch with 4 implants placed according to All-On-4® concept to support maxillary fixed and removable prostheses. A BioHPP® framework and polymethylmethacrylate “PMMA” crowns were digitally fabricated on the 3D model. The test groups were divided according to the type of attachment into two groups. Group A, the BioHPP® framework was cemented to four titanium copings over the implants to be tested as the fixed bridge (fixed-detachable prosthesis). Group B, the same framework was picked up after relief and then seated on the ball attachments to be tested as the removable overdenture. The results obtained showed that: Higher microstrains were observed on the loaded side of distal implants in groups A and B when vertical loads were applied rather than oblique loads. On the other hand, microstrains were found to be lower on the unloaded side when vertical loads were applied than when oblique loads were applied.