Black stain and dental caries in Filipino schoolchildren

Black stain is defined as dark pigmented exogenous substance in lines or dots parallel to the gingival margin and firmly adherent to the enamel at the cervical third of the tooth crowns in the primary and permanent dentition.

This study was conducted to assess the prevalence of black stain on teeth of Filipino children and to determine a possible association between black stain and caries levels. The study was designed to test the following hypotheses: (i) the prevalence of black stain does not differ between children from schools with oral health intervention programs and those from schools without an intervention program, (ii) the prevalence of black stain does not differ in children attending easily accessible and remote schools, (iii) caries prevalence and caries experience do not differ in children with and without black stain and (iv) the caries distribution at the surface level does not differ in children with and without black stain.

In total, 32 elementary schools were included. 19 schools with a comprehensive school-based preventive oral health program, seven schools with a basic preventive program and six control schools. All sixth graders of these schools (n=1748) aged 11.7+/-1.1 years were clinically examined for black stain. DMFT was assessed in 1121 children by seven calibrated dentists using WHO criteria. DMFS was scored in 627 children by two calibrated dentists.

Black stain was found in 16% of this population. The prevalence of black stain did not differ significantly between children attending schools with different oral health intervention programs. Thus, hypothesis 1 was accepted. The prevalence of black stain was significantly higher (P<0.05) in remote than in more accessible schools. Thus, hypothesis 2 was rejected. Children with black stain had significantly lower (P<0.05) caries prevalence and caries experience than children without black stain. Thus, hypothesis 3 was rejected. No difference was found in the DMFS pattern of occlusal, smooth and proximal surfaces between children with and without black stain. Thus hypothesis 4 was accepted.

The presence of black stain is associated with lower levels of caries, but a difference in the distribution of caries in black stain children was not noticed. The interplay between black stain, caries, oral microflora and diet remains unclear and urges further research.