Rebecca L. Slayton

Tuftelin, Mutans Streptococci, and Dental Caries Susceptibility

The purpose of this study was to identify genetic factors that contribute to dental caries susceptibility, either alone or in combination with environmental factors. Dental examinations were performed and buccal swab samples collected from 3- to 5-year-old children with at least 4 surfaces of decay, or with no evidence of decay. SNP assays for each of 6 candidate genes were performed for all cases and controls. Chi-square analysis and regression analysis were used for the evaluation of individual gene effects, environmental effects, and gene-environment interactions. There were no significant associations between single candidate genes and caries susceptibility. Levels of S. mutans were positively and Lactobacilli were negatively associated with caries. Regression analysis revealed a significant interaction between tuftelin and S. mutans, with 26.8% of the variation in dmfs explained by the interaction. Future research will focus on the identification of these additional factors and the development of functional assays so that these interactions can be better understood.

Genome-wide Association Scan for Childhood Caries Implicates Novel Genes

Dental caries is the most common chronic disease in children and a major public health concern due to its increasing incidence, serious health and social co-morbidities, and socio-demographic disparities in disease burden. We performed the first genome-wide association scan for dental caries to identify associated genetic loci and nominate candidate genes affecting tooth decay in 1305 US children ages 3-12 yrs. Affection status was defined as 1 or more primary teeth with evidence of decay based on intra-oral examination. No associations met strict criteria for genome-wide significance (p < 10E-7); however, several loci (ACTN2, MTR, and EDARADD, MPPED2, and LPO) with plausible biological roles in dental caries exhibited suggestive evidence for association. Analyses stratified by home fluoride level yielded additional suggestive loci, including TFIP11 in the low-fluoride group, and EPHA7 and ZMPSTE24 in the sufficient-fluoride group. Suggestive loci were tested but not significantly replicated in an independent sample (N = 1695, ages 2-7 yrs) after adjustment for multiple comparisons. This study reinforces the complexity of dental caries, suggesting that numerous loci, mostly having small effects, are involved in cariogenesis. Verification/replication of suggestive loci may highlight biological mechanisms and/or pathways leading to a fuller understanding of the genetic risks for dental caries.

An oral health curriculum for medical students at the University of Washington.

Oral health disparities are a major public health problem, according to the U.S. Surgeon General. Physicians could help prevent oral disease, but lack the knowledge to do so. To create an oral health curriculum for medical students at the University of Washington School of Medicine, the authors (beginning in 2003) (1) reviewed current evidence of medical education and physician training in oral health, (2) developed oral health learning objectives and competencies appropriate for medical students, and (3) identified current oral health content in the undergraduate curriculum and opportunities for including additional material. The authors identified very few Medline articles on medical student education and training in oral health. The United States Medical Licensing Examination Steps 2 and 3 require specific clinical knowledge and skills in oral and dental disorders, but other national curriculum databases and the Web site of the Liaison Committee on Medical Education devote no significant attention to oral health. To develop learning objectives, the authors reviewed major oral health reports, online oral health educational resources, and consulted with dental faculty. The curriculum was assessed by interviewing key medical school faculty and analyzing course descriptions, and was found to be deficient in oral health content. The authors developed five learning themes: dental public health, caries, periodontal disease, oral cancer, and oral–systemic interactions, and recommend the inclusion of corresponding competencies in targeted courses through a spiral curriculum. Current progress, the timeline for curriculum changes at the University of Washington, and the ethical values and attitudinal shifts needed to support this effort are discussed.

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.

Fluoride Use in Caries Prevention in the Primary Care Setting

Dental caries remains the most common chronic disease of childhood in the United States. Caries is a largely preventable condition, and fluoride has proven effectiveness in the prevention of caries. The goals of this clinical report are to clarify the use of available fluoride modalities for caries prevention in the primary care setting and to assist pediatricians in using fluoride to achieve maximum protection against dental caries while minimizing the likelihood of enamel fluorosis.

A New Oral Health Elective for Medical Students at the University of Washington

Background: Oral health is an important but inadequately addressed area in medical school curricula. Primary care practitioners are in an ideal position to help prevent oral disease but lack the knowledge to do so. Purposes: We developed an oral health elective that targeted 1st- and 2nd-year medical students as part of a previously described oral health initiative and oral health curriculum. Methods: To promote interprofessional collaboration, we utilized medical–dental faculty teams for lectures and hands-on peer instruction by dental students for clinical skills. Results: Evaluations revealed positive shifts in attitudes toward oral health and significant gains in oral health knowledge and self-confidence. Students rated the course highly and advocated for further integration of oral health into required medical curricula. Conclusions: We describe the elective including curriculum development, course evaluation results, and steps for implementing a successful oral health elective into medical education. We highlight interprofessional collaboration and constituency building among medical and dental faculty and administrators.

Maintaining and Improving the Oral Health of Young Children

Oral health is an integral part of the overall health of children. Dental caries is a common and chronic disease process with significant short- and long-term consequences. The prevalence of dental caries for the youngest of children has not decreased over the past decade, despite improvements for older children. As health care professionals responsible for the overall health of children, pediatricians frequently confront morbidity associated with dental caries. Because the youngest children visit the pediatrician more often than they visit the dentist, it is important that pediatricians be knowledgeable about the disease process of dental caries, prevention of the disease, and interventions available to the pediatrician and the family to maintain and restore health.

Nonsense mutations in the COL1A1 gene preferentially reduce nuclear levels of mRNA but not hnRNA in osteogenesis imperfecta type I cell strains.

Osteogenesis imperfecta (OI) is a heterogeneous disorder of type I collagen resulting in varying degrees of severity. The mildest form of OI (Type I) is associated with bone fragility, normal or near normal stature and blue sclerae. All forms of OI are the result of mutations in COL1A1 or COL1A2, the genes that encode the proalpha1(I) and proalpha2(I) chains of type I collagen, respectively. Mutations identified in patients with OI type I lead to premature termination codons and allele-specific reductions of nuclear mRNA (termed nonsense-mediated mRNA decay or NMD), resulting in a COL1A1 null allele. In mammals, this process primarily effects RNA that co-purifies with the nuclear fraction of the cell. Using a semi-quantitative RT-PCR assay, we compare the relative amounts of normal and mutant transcripts in unprocessed hnRNA and mature mRNA isolated from the nuclear fraction of cells from 11 OI type I individuals with previously identified mutations distributed throughout the COL1A1 gene. While we detect about equal amounts of normal and mutant hnRNA from each cell strain, there is preferential reduction in the relative amount of mutant mRNA when compared to normal; only the cell strain with a mutation in the last exon escapes the major effects of NMD. Our data indicate that NMD targets mRNA rather than hnRNA for degradation, and that this occurs either during or after splicing but prior to cytoplasmic translation.

Increased Enamel Hypoplasia and Very Low Birthweight Infants

Birth cohort studies of developmental defects of enamel (DDE) and early childhood caries (ECC) in very low birthweight (VLBW) and normal birthweight (NBW) infants are rare. In this birth cohort of 234 VLBW and 234 NBW infants, we report the incidence of ECC and DDE at 8 and 18-20 mos of corrected age. Infant medical and maternal socio-demographic data were abstracted from medical records at birth. Dental assessments for ECC and DDE (enamel hypoplasia, demarcated and diffuse opacities) were completed at 8 and 18-20 mos. The incidence of hypoplasia was significantly higher in VLBW compared with NBW infants (8 mos, 19% vs. 2%; 18 mos, 31% vs. 8%). The incidence of ECC (International Caries Detection and Assessment System: ICDAS ≥ 2) was 1.4% (8 mos) and 12% (18-20 mos) and was similar between the VLBW and NBW groups. At both ages, using a beta-binomial regression model to control for potential confounders (maternal and infant characteristics), we found increased risk for enamel hypoplasia among the VLBW infants compared with the NBW infants. African Americans had a lower risk for enamel hypoplasia at 18-20 mos. The VLBW infants should be monitored for ECC due to the presence of enamel hypoplasia.

Impact of Chronic Condition Status and Severity on Dental Utilization for Iowa Medicaid-Enrolled Children

Background:Although Medicaid-enrolled children with a chronic condition (CC) may be less likely to use dental care because of factors related to their CC, dental utilization for this population is poorly understood. Objective:To assess the relationship between CC status and CC severity, respectively, on dental utilization for Iowa Medicaid-enrolled children. Research Design:Retrospective cohort study of Iowa Medicaid data (January 1, 2003 to December 31, 2006). Subjects:Medicaid-enrolled children aged 3 to 14 (N = 71,115) years. Measures:The 3M Corporation Clinical Risk Grouping methods were used to assess CC status (no/yes) and CC severity (episodic/life-long/malignancy/complex). The outcome variable was any dental utilization in 2006. Secondary outcomes included use of diagnostic, preventive, routine restorative, or complex restorative dental care. Results:After adjusting for model covariates, Iowa Medicaid-enrolled children with a CC were significantly more likely to use each type of dental care except routine restorative care (P = 0.86) than those without a CC, although the differences in the odds were small (4%–6%). Compared with Medicaid-enrolled children with an episodic CC, children with a life-long CC were less likely to use routine restorative care (P < 0.0001), children with a malignancy were more likely to use complex restorative care (P < 0.03), and children with a complex CC were less likely to use each type of dental care except complex restorative care (P = 0.97). Conclusions:There were differences in dental utilization for Iowa Medicaid-enrolled children by CC status and CC severity. Children with complex CCs were the least likely to use dental care. Future research efforts should seek to understand why subgroups of Medicaid-enrolled children with a CC exhibit lower dental utilization.