Micro-CT Detection and Characterization of Porosity in Luting Cements

To evaluate porosity volume and localization in luting cements under fixed dental prostheses after cementation using micro-computed tomography (CT).

Seventy-seven sound molars were circumferentially prepared to receive all-ceramic crowns, and IPS e.max ceramic copings were fabricated according to the manufacturer's instructions. For this study, different dental luting cements were used: eight resin-based cements (Variolink II, RelyX ARC, Clearfil Esthetic, BisCem, RelyX U100, Panavia EX, Super Bond C&B, and Multilink Automix), one resin-modified glass ionomer (Ketac Cem Plus), one glass ionomer (Ketac Cem), and one polycarboxylate (Durelon). Specimens were scanned with a micro-CT (SkyScan) for detection and comparison of the cements' porosities. Statistical analyses were performed using Kruskal-Wallis one-way ANOVA and Bonferroni's adjusted Mann-Whitney U tests.

Multilink Automix (Volume = 0.11 ± 0.08 mm³ ; Surface Area = 1.63 ± 1.31 mm² ), Ketac Cem Plus (Volume = 0.22 ± 0.21 mm³ ; Surface Area = 4.32 ± 3.71 mm² ), and Variolink II (Volume = 0.34 ± 0.38 mm³ ; Surface Area = 6.47 ± 5.10 mm² ) contained less porosity (p < 0.001) than all other cements. All other cements were not significantly different from one another (p > 0.05); however, the volume and surface area of the porosity found in the other tested luting cements were significantly greater than those of the Multilink Automix, Ketac Cem Plus, and Variolink II (p < 0.001), all of which demonstrated no significant differences (p > 0.05).

The liquid and powder forms prepared by manually mixing the cements were found to cause greater porosity.