Faculty Bibliography

Actinomyces naeslundii genospecies 2 (gsp-2) are members of the autochthonous oral flora. Chromosomal DNA fingerprinting (CDF) with SmaI revealed extensive genetic diversity among A. naeslundii gsp-2 strains within individual mothers and children. There was a low prevalence of genotype match among A. naeslundii gsp-2 strains between all mother and child pairs.

The objective of the present study was to design a PCR-generated DNA probe and determine the specificity of the probe for the identification of clinical isolates of Streptococcus sanguinis. To do this, we examined over 200 arbitrarily primed PCR (AP-PCR) amplicon patterns obtained with DNA from clinical isolates of S. sanguinis. A 1.6-kb DNA amplicon that was common to all AP-PCR profiles was extracted from agarose gels and then cloned and sequenced. A search for a similar sequence in the GenBank database with the BLASTN program revealed that the 1.6-kb DNA fragment comprised an intergenic region between two housekeeping genes, uncC (proton-translocating ATPase) and murA (UDP-N-acetylglucosamine enolpyruvyl transferase). Three digoxigenin-labeled DNA probes were synthesized on the basis of the sequence of the 1.6-kb fragment: the sequence of probe SSA-1 contained the proton-translocating ATPase (uncC) and the entire intergenic region, the sequence of probe SSA-2 contained only the intergenic region, and the sequence of probe SSA-3 contained an internal region of the murA gene. Dot blot hybridization showed that the three probes displayed signals for hybridization to both S. sanguinis strain ATCC 10556 and the S. sanguinis clinical isolates. Probe SSA-1, however, hybridized to DNA from S. oralis and S. mitis. Probe SSA-3 hybridized to DNA from S. gordonii, S. mitis, S. oralis, S. parasanguinis, and S. vestibularis. The probe SSA-2-specific intergenic region appeared to be specific for S. sanguinis. The results from this study suggest that probe SSA-2 may serve as a species-specific DNA probe for the identification of clinical isolates of S. sanguinis.

OBJECTIVE: To study whether the caries status of the primary dentition correlated with status of the permanent in the same cohort over an eight-year period. To determine whether the caries status of the primary dentition can be used to predict caries in the permanent dentition. METHODS: A total of 362 children, 3 - 4 years old in the baseline study in 1992 were re-examined in 2000 based on WHO criteria and methods. RESULTS: Statistically significant associations were observed between the caries prevalence in primary and permanent teeth (P < 0.01) and between DMFT(s) and dmft(s) (P < 0.01). Children who had caries in the primary teeth were nearly three times more likely to have caries in the permanent teeth (RR = 2.6,95% CI = 1.4 - 4.7, P < 0.001). The highest sensitivity (93.9%) for prediction caries in the permanent dentition was found in caries presence on any of the eight primary molars, for which the relative ratio was 3.3 (95% CI = 1.8 - 6.1, P < 0.001) and the positive prediction value was 85.4%. CONCLUSION: The study determinate clearly that caries status in the primary teeth can be used as a risk indicator for predicting caries in the permanent dentition

In the current literature database, information on microbiological attributes to caries outcomes in African American populations is limited and scattered. Few reports have discussed MS infection and transmission from African American mothers to their children. During the past few years, the research group at the University of Alabama at Birmingham and the Jefferson County Pubic Health Department have done a series of extensive studies to systematically investigate the prevalence of MS colonization, the time of initial MS infection as defined as "the window of infectivity," the source of MS transmission as defined as "the fidelity of transmission, and the chemotherapeutic management of MS transmission and caries prevention. The objective of this report was to summarize the main significant findings generated during a period of 15 years of study. One limitation of the studies outlined in this article is that the research populations were predominately African American families. The inclusion of white and other minorities would make the conclusions more generalizable to the US population as a whole. Nevertheless, the information presented in this report can serve as baseline knowledge for future studies of caries etiology in African American and other ethnic populations.

Several cross-sectional studies report that caries in primary teeth is correlated with caries in permanent teeth. This eight-year cohort study sought to determine if caries in the primary dentition can predict caries in the permanent dentition of the same individuals and, if so, with what degree of prediction accuracy. A total of 362 Chinese children, from 3 to 5 years old at the time of the 1992 baseline study, were re-examined in 2000. The study found statistically significant associations between caries prevalence in primary and permanent dentitions (p < 0.01). Children having caries in their primary teeth were three times more likely to develop caries in their permanent teeth (relative ratio = 2.6, 95% CI = 1.4-4.7; p < 0.001). Caries on primary molars had the highest predictive value (85.4%). This study demonstrates that caries status in the primary teeth can be used as a risk indicator for predicting caries in the permanent teeth

In a randomized clinical trial, we evaluated the effect of a 10% chlorhexidine varnish (Chlorzoin) on the mother-child transmission of Streptococcus mutans and on subsequent caries experience. Chlorhexidine (n = 38) or a placebo varnish (n = 37) was applied to the dentitions of 75 mothers at a time when their first babies were about 6 months old (approximate time of first tooth emergence). Three more applications at weekly intervals and subsequent applications at 6-month intervals followed the initial application. The mother-child pairs were followed up until the child's fourth birthday. Maternal salivary S. mutans levels in the treatment group remained significantly lower (p < 0.05) compared to the control group up to 12 months after the initial application. However, this intervention did not significantly alter the S. mutans colonization in children or the caries increment in either the mother or the child.

Actinomyces are difficult to identify using serological and biochemical methods but genotyping is an efficient and reliable means of bacterial characterization and can be used to determine clonal identity. The purpose here was to genotype 13 American type culture collection (ATCC) reference strains representing six different oral Actinomyces spp. by using chromosomal DNA fingerprinting (CDF), arbitrarily primed-polymerase chain reaction (AP-PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In CDF analysis, BamHI, BstEII and SmaI yielded digestion patterns revealing characteristic differences among the known Actinomyces spp., with SmaI demonstrating optimal resolution. Amplicons generated by AP-PCR with primer OPB-07 displayed banding patterns that permitted discrimination of all Actinomyces strains tested. PCR-RFLP with MnlI digests generated fragment patterns that also characterized the reference strains. Collectively, genotypic profiles generated by CDF, AP-PCR and PCR-RFLP permitted differentiation of all 13 ATCC Actinomyces strains. SmaI CDF analysis of 18 clinical isolates of catalase-positive A. naeslundii genospecies 2 revealed extensive genetic diversity among these strains. These molecular approaches may be useful in determining genetic diversity within oral Actinomyces populations and fidelity of Actinomyces transmission between mother and child.