THE EFFECT OF THERMOCYCLING ON THE MARGINAL INTEGRITY OF 3D PRINTED AND MACHINED HYBRID RESIN-CERAMIC CROWNS: AN IN‐VITRO STUDY

Document Type : Original Article

Authors

1 Associate Professor, Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Modern University for Technology and Information, Cairo, Egypt.

2 Assistant Professor of Fixed Prosthodontics, Faculty of Dentistry, Modern University for Technology and Information, Egypt

Abstract

Objective: To compare the marginal integrity of 3D printed hybrid resin-ceramic crowns to that of milled lithium disilicate and milled hybrid resin ceramic crowns.
Materials and methods: A typodont prepared lower first permanent molar tooth was optically scanned for manufacturing 12 crowns divided into three groups (n=4). Group 1 were milled from lithium disilicate ceramics (IPS e.max CAD), group 2 were milled from hybrid resin-ceramic (Nanoksa G-plus ®, Ionx) while group 3 were 3D printed from hybrid resin-ceramic (Nanoksa Bioguard ®, Ionx). Using a digital stereomicroscope (Leica L2, Germany), the marginal gap was assessed before and after 5000 cycles of thermocycling. The collected data were analyzed using Wilcoxon signed ranks test and Kruskal-Wallis test followed by Mann-Whitney test (P ≤ 0.05).
Results: The values of the marginal gaps of the three groups before thermocycling reported no statistically significant difference (p-value = 0.090). In addition, the values of the marginal gaps of the three groups after thermocycling reported no statistically significant difference (p-value = 0.387). Regarding the effect of thermocycling, group 1 showed a non-statistically significant difference in the marginal gap values (p-value = 0.343). However, group 2 and 3 exhibited a statistically significant increase in the marginal gap values after thermocycling (p-value = 0.011 and 0.025 respectively)
Conclusion: The marginal gap values of 3D printed hybrid resin-ceramic crowns was similar to milled lithium disilicate and hybrid resin-ceramic crowns. Although, the thermocycling negatively affected the marginal gap, this effect remains within the accepted clinical range.

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Egyptian Dental Journal
Volume 71, Issue 3 - Serial Number 4
Fixed Prosthodontics, Removable Prosthodontics and Dental Materials
July 2025
Pages 2355-2361

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