Faculty Bibliography

A total of 1344 children, 3-5 yr old, from two rural counties, Haidian and Miyun, close to Beijing, China, were examined in 1992. A modified DDE Index was employed in this study, and a pre-designed formula was used to calculate an enamel defect score (EDS) for each individual in the study. Oral examination was performed by one dentist under natural light using a standard mouth mirror and dental probe. Developmental enamel lesions were diagnosed without drying or cleaning the teeth prior to examination. Results from this study showed that primary teeth with defective enamel were seen in 23.9% of the children examined, opacity in 1.6%, and hypoplasia in 22.2%. Among the teeth, maxillary central and lateral incisors were affected by enamel hypoplasia most often (40.8% and 39.2%), followed by maxillary canines (25.7%), maxillary 1st molars (22.1%), and mandibular 1st molars (18.5%). The enamel defects occurred more frequently on the buccal surfaces of teeth than on any other surface. The study did not find a significant association of the children's age, family socioeconomic status, and anthropometric measurements with the distribution of enamel defects. However, there was a significantly higher prevalence of teeth with defects in males compared to females (P < 0.001), as well as mean tooth surfaces with defects (P < 0.05), and mean EDS (P < 0.05). Children born prematurely were shown to have four times more enamel lesions than children who were full term (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Previous cross-sectional studies using bacteriocin profiles, serotyping, or genotyping suggest that mothers are the principle source of mutans streptococci (MS) to their infants. This study determined the commonality of MS genotypes between mothers and their infants at the time of initial acquisition. Oral bacteria of mothers and their infants were monitored from birth for approximately 3 years at three-month intervals. Genotypes of MS in infants appeared identical to those present in mothers in approximately 71% of 34 mother-infant pairs studied. Interestingly, female infants acquired MS genotypes identical to their mothers' with significantly greater fidelity than male infants (88% vs. 53%). Homology of genotypes between mothers and their infants at initial acquisition strongly suggests that MS strains were transmitted from mother to infant and that this transfer exhibited gender specificity. In no instance did we observe homology of genotypes between fathers and infants or fathers and mothers, further supporting the notion that acquisition of MS in humans follows maternal lines. Although the prevalence of dental caries was low in this young child population (11/34; 32%), we observed that male children who harbored the same genotype as their mothers had a 13 times greater likelihood of having caries than female children who acquired their mothers' strain; this difference was statistically significant (p < 0.01). Although we do not know the biological mechanisms governing fidelity of acquisition between a mother and her infant, our data suggest that caries outcome may be, in part, determined by both the source of MS and the presence of a specific genotype of MS.(ABSTRACT TRUNCATED AT 250 WORDS)

This case-control study compared the prevalence and concentration of mutans streptococci (MS) in saliva between children with and without enamel hypoplasia (EHP). A total of 486 3- or 4-year-old Chinese children were initially screened for EHP, then distributed into two groups: 234 children diagnosed as having EHP were assigned to the case group; 252 who were free of EHP were included in the control group. The concentration of MS in saliva was assayed for each child. Nutritional status was deduced from body height and weight. Birth weight, prematurity, and nursing history were also determined. MS were found in 94.7% of the study population. The differences in MS concentrations were not associated with low birth weight, prematurity, length of breast feeding, or body height and weight. A statistically significant association existed between the presence of EHP and high counts of MS (p < 0.001). High MS counts were correlated with severity of enamel defects (p < 0.001). When the caries status of the children was controlled as the confounding factor in statistical analyses, the association between EHP and MS decreased but still remained significant (p = 0.025). This study shows that high MS counts are correlated with EHP, suggesting that irregularities in enamel surfaces could be a contributing factor that fosters the increased colonization of MS in the mouths of children.