Antibody response to actinomyces antigen and dental caries experience: implications for caries susceptibility

Epidemiological and Microbiome Characterization of Black Tooth Stain in Preschool Children

OBJECTIVE

To assess the epidemiologic attributes and microbial variations associated with extrinsic black tooth stain (BTS) among Chinese preschool children.

METHODS

This cross-sectional study included 250 preschool children (3-4 years) from three kindergartens in Shanghai, China. Following clinical examination, and using a case-control design, saliva and dental plaque specimens were collected from caries-free participants with (n = 21, BTS group) and without (n = 48, control group) BTS. The chi-square test and logistic regression model were used to evaluate factors associated with BTS. 16S rRNA sequencing were used to characterize the associated microbial communities.

RESULTS

BTS was detected in 12.4% of participants, with a mean of 13.7 black-stained teeth. Participants with BTS had a lower caries burden and better oral hygiene (P = 0.003). Children with less frequent intake of marmalade or honey (P = 0.033) and regular application of fluoride (P = 0.007) had a lower likelihood of having BTS. Microbiota analysis revealed 14 phyla, 35 classes, 63 orders, 113 families, 221 genera, 452 species, and 1,771 operational taxonomic units (OTUs). In terms of microbial diversity, no significant differences were observed in the saliva of the two groups (P > 0.05). Dental plaque from the BTS group exhibited higher OTU richness but lower evenness than that from the control group (Chao P = 0.006, Shannon P = 0.007, respectively) and showed a significant difference in β diversity (P = 0.002). The microbiome in the two groups was characterized by various microbial biomarkers, such as Pseudomonas fluorescens, Leptotrichia sp._HMT_212, Actinomyces sp._HMT_169, and Aggregatibacter sp._HMT_898 in plaques from the BTS group. Functional analysis of the microbial species suggested the existence of a hyperactive metabolic state on teeth surfaces with BTS plaques and revealed that ferric iron, the iron complex transport system, and the iron (III) transport system were more abundant in BTS plaque samples.

CONCLUSIONS

This study provides insights into the epidemiologic and microbial features of BTS in preschool children. The microbiome in BTS is characterized by various microbial biomarkers, which can serve as indicators for BTS diagnosis and prognosis.

Factors associated with black tooth stain in Chinese preschool children

OBJECTIVES

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

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

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.

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Acidic proline-rich protein Db and caries in young children

Polymorphic, acidic proline-rich proteins (PRPs) in saliva influence the attachment of bacteria associated with caries. Our aims were to detect one of three acidic PRP alleles of the PRH1 locus (Db) using polymerase chain-reaction (PCR) on genomic DNA, and to determine its association with caries. DNA was obtained from buccal swabs from Caucasian and African-American children, and their caries experience was recorded. PCR primers designed around exon 3 of the PRH1 locus gave a 416-base product representing Db and a 353-base product representing the other two alleles (Pa or Pif). In Caucasians, Db gene frequency was 14%, similar to Db protein from parotid saliva. In African-Americans, however, it was 37%, 18% lower than Db from parotid saliva (reported previously). Compared with African-Americans, all Caucasians had significantly greater Streptococcus mutans colonization, but only Db-negative Caucasians had significantly more caries. Alleles linked to Db may explain racial differences in caries experience.