BACKGROUND: There is some cases of perforation and undesirable properties of some primary molars stainless steel crowns. AIM: The aim of this study was to compare the physical and mechanical properties of different commercial brands of these crowns. METHODS: In an in vitro study, 10 stainless steel tooth crowns of the second primary mandibular molars size 6 of 4 different commercial brands (a total of 280 crowns) were evaluated. These crowns were included KTR Pre-trimmed and Crimped Nichro Stainless Steel Primary Molar Crowns (KTR, China); 3M Stainless Steel Primary Molar Crowns (ESPE, St paul; USA); NuSmile SSC Pre-contoured (Inc, Houstone, TX; USA) and Kids crown (Shinghung, Seoul; Korea). Corrosion and galvanic corrosion, wear, microhardness, compressive strength, fatigue strength of crowns and weight percent of elements were investigated. RESULTS: The highest rate of microhardness, compressive and Fatigue strength of the crowns were made by Nu Smile > 3M > Kids Crown > KTR respectively. The highest rate of corrosion potential in corrosion and Galvanic corrosion tests was in KTR > Kids crowns > 3M > Nu smile respectively. The order of crown wear was KTR > Kids Crown > 3M > Nu Smile respectively. The highest amount of nickel element was found in the Nu Smile crown and the highest amount of chrome in the 3M crown with a significant difference with others (p < 0.001). The KTR and Kids crowns lacked molybdenum. CONCLUSION: The results showed that Nu Smile crown has better physical and mechanical properties than other evaluated crowns in this study.
