This randomized clinical trial compared the clinical outcomes of two full‑coronal restorations (stainless steel crowns [SSCs] and zirconia crowns Nu/ZR) in carious primary molars teeth. Children attending the King Abdulaziz University, Faculty of Dentistry clinics who need restorations will be screened for inclusion criteria till 120 teeth are recruited (60 teeth for SSC restorations and 60 for Nu/ZR restorations). Split mouth technique will be used to ensure equalizing variables for both groups. Randomization will be done using SPSS software version 20.0 (Armonk, NY; IBM Corp., USA). A simple descriptive statistic will be used for analysis using Wilcoxon Signed‑Rank test. The level of significance will be set at (α = 0.05) and level of confidence at (95%). While looking at the improvements in gingival health relative to interventions, both Zirconia and SSC have significant changes through all time points. However, Zirconia performed better at the 3rd month with 80% compared to SSC with only 13.3% improvement with P < 0.001 and 0.005, respectively. At 6th month, all samples under group zirconia already improved whereas only 73.3% from SSC show improvement. The remaining samples happened to have positive changes at the 12th month. Regarding the plaque retention also the Zirconia Crowns shows improve performance than SSC. As both SSC and Zirconia crowns presented to be an excellent choice for posterior teeth restorations, however, we can conclude that Zirconia crowns performed better regarding gingival response to the material of restoration and plaque retention despite its high cost.