Evaluation of marginal and internal gaps of Ni-Cr and Co-Cr alloy copings manufactured by microstereolithography

Abstract

PURPOSEThe purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental µ-SLA system.MATERIALS AND METHODSTen study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope (160 ×) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (α=.05).RESULTSThe mean (±standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: 81.5±73.8, 98.1±76.1, 87.1±44.8, and 146.8±78.7 µm in the LW group; 76.8±48.0, 141.7±57.1, 80.7±47.5, and 194.69±63.8 µm in the NC group; and 124.2±52.0, 199.5±71.0, 67.1±37.6, and 244.5±58.9 µm in the CC group.CONCLUSIONThe marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

A systematic review on the accuracy of manufacturing techniques for cobalt chromium fixed dental prostheses

“…Mikrotek N/S a [36] 3Shape D700 [38,42,44,48] Yenadent N/S [36] BEGO Wirobond 280 [37,44] BEGO Fornax [39,45,46] 3Shape D800 [45,46] Yenadent DC40 [43] BEGO Wirobond C [40,48,49,52] BEGO Nautilus CC [44,52] 3Shape D640 [52] Concept laser M1 [36,38,42,44] BEGO N/S [36] Renfert N/S [40] 3Shape N/S [37] Eosint M270 [13,39,43,46,48] EOS MP1 [39] N/S [37,38,41,48,49] 3M Lava [51] BEGO N/S [40] EOS SP2 [13,42,43,46,48] Straumann Cares [47,50] Straumann milling [47,50] Straumann Coron [47,…”

Effect of full arch two scanning techniques on the accuracy of overdenture conventional and CAD/CAM Co-Cr bars

“…Restorations consisting of more than four implants were reported to show limited accuracy on both optical and conventional impressions ( Gedrimiene et al, 2019 , Rech-Ortega et al, 2019 ). Some studies have revealed that conventional impressions may be more appropriate for long-span or full-arch restorations ( Ahlholm, et al, 2018 , Anan and Al-Saadi, 2015 , Kim et al, 2017a , Mangano et al, 2017 ).…”

effect of coping materials and designs to the marginal adaptation of metal porcelain crowns

“…Ni-Cr has low corrosion resistance and is not biocompatible because nickel can cause allergic reactions. In addition, the addition of beryllium to Ni-Cr which functions as a hardener, grain structure refiner, and to reduce the combustion temperature is carcinogenic, but is still within the clinically acceptable threshold of 0.002 ppm 3 . Concerns about the toxicity due to the use of nickel and beryllium, although still within clinically accepted limits, have spurred researchers to develop Co-Cr alloys as an alternative that can be used in porcelain metal crown restorations.…”

“…The acceptable vertical marginal adaptation of a restoration ranges from 10 -160 µm. Clinically, for the long-term resilience of a restoration, the acceptable marginal adaptation difference is 40-120 µm 8 . In selecting the type of alloy for coping, one of several important factors to consider is the dimensional accuracy of the resulting coping.…”