Comparison of Retention Forces of Different Fabrication Methods of Co-Cr Crowns: Pre-sintered and Milled, Cast and Electroforming Secondary Crowns with Different Taper Angles

Abstract

To investigate the retention forces of differently fabricated secondary crowns made of Co-Cr alloy and electroforming secondary crowns considering different taper angles. Cobalt-chromium primary crowns with 0°, 1°and 2°taper angles were fabricated. Secondary crowns were made either by i) amilling and sintering, ii) castingor iii) electro-forming process. Pull-off tests were performed and data were analyzed by parametric statistics (p<0.05). With regard to the different taper angles, Co-Cr milled and cast groups, no impact on retention force was observed. Within the electroforming group, primary crowns with a taper angle of 1°showed a higher retention force than crowns with angles of 0°or 2°. With respect to the secondary crowns, primary crowns with a taper angle of 1°showed no impact on the results. Within the taper angles of 0°and 2°, the electroforming group exhibited lower retention forces than cast or milled ones. In the 0°taper angle group, milled secondary crowns displayed higher values than cast ones.

PEEK Primary Crowns with Cobalt-Chromium, Zirconia and Galvanic Secondary Crowns with Different Tapers—A Comparison of Retention Forces

“…Thirty metal abutment teeth were cast from a base metal alloy (Remanium GM800+, LOT 936, Dentaurum, Ispringen, Germany,) using an artificial molar tooth as a template for the silicone duplicating technique [22]. The metal abutment teeth were scanned (Ceramill map300, AmannGirrbach, Koblach, Austria; Figure 1) and thirty primary crowns were designed (Ceramill Mind 2.3.0, AmannGirrbach) with three different tapers (0° with a chamfer, 1°, and 2°, n = 10 each).…”

“…This, together with the path of insertion vertical to the ground, ensured a self-aligning of the complete system. The crosshead speed was set at 50 mm/min [22] and twenty cycles of each specimen were measured (Figure 6). …”

“…Previous studies measuring the retention force of double crowns examined the influence of different material groups, number of pull-off cycles, and different taper angles [8,16,22,23]. Among double crowns, cylindrical telescopic crowns with parallel walls have to be distinguished from conus crowns with taper angles greater than 0° [11].…”