Factors associated with black tooth stain in Chinese preschool children

The objective of this study was to investigate the prevalence of black tooth stain and associated factors in primary dentition in Shanghai, China.

Through a cross-sectional design, preschool children were randomly recruited from 12 kindergartens. Children's dental caries were assessed on the number of decayed, missing, and filled teeth (dmft) and surfaces (dmfs). The presence of black tooth stain was examined, and the visible plaque index was calculated. Questionnaires were completed by the children's parents or guardians. Negative binomial regression was used to investigate the associated factors.

A total of 2,023 children were invited, and 1,397 examined participants with questionnaire data were included in final analysis. The rate of black tooth stain was 9.9 % with mean age of 4.55 years. Compared to children without black stain, children with black stain had a significant lower prevalence and experience of dental caries (P < 0.01). Factors for black stain were age, born in Shanghai, parents' higher education level, lower visible plaque index and mean dmfs, less use of nursing bottle, food with more soy sauce, and history of pneumonia.

Preschool children with black tooth stain had fewer dental caries. Further studies are warranted to explore the microbiologic risk factors for black tooth stain and to evaluate the causal-effect factors using prospective study design.

In clinics, dentists should pay more attention to this aesthetic problem for the relative high prevalence of black tooth stain in primary dentition. Also, the related factors can be explained to parents for the prevention of black tooth stain in children.