USAGE OF A SPECIAL SHAPE SCREWS FOR DIRECT ZIRCONIUM DIOXIDE SUPRASTRUCTURE FIXATION TO MULTI-UNIT ABUTMENTS WITHOUT THE USE OF A Ti-BASE PLATFORM

Abstract

Screw-retained implant-supported restorations, both single and full-arch, are becoming increasingly popular. These restorations prevent negative subgingival inflammation associated with cement residue by eliminating intraoral cementation of the restoration to the abutment. Traditionally, screw-retained restorations are cemented to Ti-base abutments in the laboratory and delivered to the clinician as such. The restoration may separate under function from the Ti-base it was luted to. Direct fixation of zirconia structures to multi-unit abutments using standard screws, although possible, is risky due to the design of the screws, which were designed to press the Ti-base platform, i.e., metal-to-metal contact, not zirconia. To eliminate these risks, one can use screws of a special shape, which allows safe and reliable direct fixation of the zirconia prosthesis to multi-unit abutments without the risk of its fracture at the point of contact with the abutment.