Comparison of Compressive Strength Between Traditional and Novel Open-Faced Stainless Steel Crowns Filled With Different Restorative Materials.

Purpose: To compare the compressive strength of traditional open-faced stainless-steel crown (OFSSC) to novel Preformed OFSSC (POFSSC) filled with different restorative materials. Methods: Seventy-five uniform 3D-printed models were divided into five groups (n=15): Group one (G1) traditional OFSSC; Group two (G2) POFSSC with restorative composite; Group three (G3) POFSSC with bulk-fill composite; Group four (G4) POFSSC with flowable resin restorative; and Group 5 (G5) POFSSC with resin-reinforced glass-ionomer. Samples were subjected to 1,000 cycles of thermocycling, at five degrees to 55 degrees Celsius, followed by a tactile exam. Instron was used for compressive strength test, with the maximum force at fracture initiation recorded in Newtons (N). Failure of the facial-surface was categorized as <50% facial-surface chipped, >/=50% to <100% facial-surface chipped, or the entire facial-surface came-off. One-way analysis of variance and the Kruskal-Wallis test was used (P<0.05). Results: All samples were intact during the tactile exam following thermocycling. The compressive strengths are ranked as: G2???784.66+/-86.29 N; G3???730.46+/-159.52 N; G4???726.33+/-150.47 N; G1???650.59+/-116.05 N; G5???556.60+/-137.65 N. The compressive strength of G2 was significantly higher than G1 (P=0.007). G5 showed significantly lower compressive strength than G2 (P=0.0), G3 (P=0.001), and G4 (P=0.001). The entire facial-surface cameoff as follows: G2???6.67%; G4???13.33%; G5???26.67%; G3???53.33%; G1???66.67%. Conclusion: Compressive strength of G2 was significantly higher than control; and G2 had the lowest percentage of the entire facial-surface coming-off.