Fit assessment of different sintering speeds of multilayer zirconia using micro-CT

Abstract

Statement of problem Data on the marginal and internal fits of speed-sintered zirconia crowns is lacking. Purpose The aim of this in vitro study was to assess the marginal and internal fit of multilayer zirconia implant crowns when sintered with 3 different sintering cycles: a standard cycle (SC), a speed cycle (SP), and a superspeed cycle (SS). Material and methods A total of 30 zirconia implant crowns were fabricated and divided into 3 groups based on the speed of the sintering cycle (n=10). Microcomputed tomography was used to scan all specimens, and the marginal and internal gaps were measured. The Kruskal–Wallis and Friedman tests were used to compare the marginal and internal gaps among the groups (α=.05). Results A statistically significant difference was detected between the SC group and the other groups (P<.05). A statistical difference was found among all groups in terms of internal gaps (P<.05). The SC group showed the lowest marginal and internal gaps, with mean values of 47.4 µm and 90.8 µm, respectively. The mean values for marginal and internal gaps were higher in the SS group (54.3 µm and 117.5 µm) and highest in the SP group (68 µm and 128.9 µm). Conclusions All groups had marginal and internal gaps within a clinically acceptable range.