Relationship of levels of trace elements in saliva and dental caries in preschool children using total reflection X-ray fluorescence technique (TXRF)⋆

Background: Considering that studies on the relationship between dental caries and trace elements present contradictory and inconclusive results, the purpose of this study was to determine the levels of salivary trace elements in saliva samples of preschool children and investigate their relationship with dental caries.Methods: In total, 120 samples of unstimulated saliva were collected from children aged 36-72 months, of both sexes, who participate in the preventative educational program in oral health at the State University of Londrina, Brazil. The children were divided into two groups, caries (n = 60) and non-caries (n = 60). Levels of Al, Cu, Fe, Mn, and Zn were analyzed by total reflection X-ray fluorescence (TXRF). Descriptive statistics, the Student's t test, Mann-Whitney U test, and Pearson's Chi-squared test were performed (P < 0.05).Results: The concentrations of Mn and Fe were significantly higher in the caries group (Mn =0.015 mg/L [0.007-0.020]; Fe =0.080 mg/L [0.031-0.239] than the non-caries group (Mn =0.010 mg/L [0.001 - 0.017]; Fe =0.044 mg/L [0.023 - 0.107]).Conclusion: The results suggest a relationship between trace elements and dental caries, indicating possible involvement of these elements in the metabolism of microorganisms involved in the carious process. In addition, the use of TXRF presented satisfactory results, with a simple and fast methodology for the detection of the studied elements.