# Biochemical Saliva Analysis and Caries Experience In Children With Black Tooth Stain

## TL;DR

Children with black tooth stain have lower tooth decay and higher levels of manganese and zinc in their saliva.

## Contribution

This study links black tooth stain to lower caries and higher salivary Mn and Zn levels in children.

## Key findings

- Children with black tooth stain had significantly lower dft scores and fewer decayed primary teeth.
- BTS(+) group showed higher caries-free teeth and significant differences in ICDAS II classification.
- Salivary Mn and Zn levels were significantly higher in children with black tooth stain.

## Abstract

Black tooth stain (BTS) is an extrinsic discolouration that typically appears along the cervical third of the buccal and/or lingual surfaces of both primary and permanent teeth, predominantly in prepubertal individuals. This study aimed to investigate the biochemical properties of saliva and assess caries experience in children with and without BTS during the mixed–dentition period.

A total of 120 children aged 7–12 years were enrolled and divided equally into BTS(+) and BTS(–) groups. Comprehensive dental examinations were conducted using dft/DMFT indices and International Caries Detection and Assessment System (ICDAS) II criteria to evaluate caries status and the presence of BTS. Unstimulated whole saliva samples were collected and analysed for flow rate, pH, buffering capacity, and ion concentrations (Cu, Fe, P, Ca, Mg, Zn, and Mn) using an inductively coupled plasma mass spectrometry (ICP-MS) method. The obtained data were analysed and compared between the groups.

The BTS(+) group demonstrated significantly lower dft scores and fewer decayed primary teeth compared to the BTS(–) group (P <0.05). A higher proportion of caries-free teeth was also observed in the BTS(+) group. Additionally, a statistically significant difference was found between the groups in terms of ICDAS II caries classification (P = 0.048). Salivary analysis showed significantly elevated manganese (Mn) and zinc (Zn) levels in the BTS(+) group, while no significant differences were found in pH, buffering capacity, flow rate, or other salivary ions. No significant correlations were observed between the severity of BTS and age, salivary parameters, or caries indices.

Children with black tooth stain exhibited a lower caries experience, which may be associated with the anticariogenic properties of higher salivary Mn and Zn levels. Additionally, elevated Mn concentrations might play a role in the formation of BTS.