1 Detection of Ni , Fe , and Cr released in saliva after 2 prefabricated metal crown placement in children 3

Dental caries is a public health problem worldwide according to WHO data. Among 20 treatments in pediatric dentistry, prefabricated metal crowns (PMCs) have been one of the most 21 successful options since they were introduced in cases of considerable tooth destruction. Our 22 objective was to detect the presence and concentration of iron (Fe), chromium (Cr), and nickel (Ni) 23 in saliva of patients who require rehabilitation with PMCs, before and after their placement. A 24 quasi-experimental study was performed in 32 patients who attended dental care in a pediatric 25 dentistry clinic at a public university and who required rehabilitation with PMCs. Parametric tests 26 (ANOVA and Pearson correlation) were performed, and a p ≤ 0.05 was considered statistically 27 significant. Statistically significant differences were found when comparing the Ni release before, 1 28 week, and 1 month after placing the crowns. Similarly, we observed a positive correlation between 29 the number of crowns and Ni release. No tests were performed for Fe and Cr because the amounts 30 of these metals were less than 0.1 ppb, which was not detectable by inductively coupled plasma 31 optical emission spectrometry (ICP-OES). The levels of Fe, Cr, and Ni released were below toxic 32 health levels. Studies are required to evaluate whether this release has negative effects at cellular 33 levels. 34