Effects of pH and Time on Nickel Ion Release from Pediatric Stainless-Steel Crowns: An In-Vitro Comparative Study

Background: Frequent use of stainless-steel crowns in pediatric dentistry has led to concerns that heavy metals in the crowns could be released into the mouth and potentially trigger allergic reactions. Of these constituents, nickel is known to be a common cause of hypersensitivity reactions. Aim: To evaluate and compare nickel ion release from pediatric stainless-steel crowns of 3M ESPE and DNTO Kids Crown at pH levels of 4.3, 5.5, and 6.3 for days 1, 7, 15, and 30. Methods: In this in-vitro study, nickel ion release (in PPM) from stainless steel crowns of 3M ESPE ( n = 60) and DNTO Kids Crown ( n = 60) in artificial saliva of pH 4.3, 5.5, and 6.3 on days 1, 7, 15, and 30 was analyzed using inductively coupled plasma-atomic emission spectrometry at Indian Institute of Technology-Bombay. Statistical analysis was performed using two-way and three-way analysis of variance (ANOVA) followed by least significant difference post hoc test and Spearman's rank order correlation. P < 0.05 was considered statistically significant. Results: In both groups (3M ESPE and DNTO Kids Crown), a significantly higher amount of nickel ion release was observed at pH 4.3. Among different time intervals, significantly maximum nickel ion release was observed on day 7. Nickel ion release from DNTO Kids Crowns was significantly higher than 3M ESPE at all the pH levels and time intervals. Conclusions: The pH of artificial saliva and nickel ion release is inversely related. The manufacturing process may affect the biodegradability of stainless-steel crowns. The maximum average nickel ion release from stainless steel crowns is below the recommended dietary intake but sufficient to cause allergic reactions.