Evidence of Early Emergence of the Primary Dentition in a Northern Plains American Indian Population.

The purposes of this study were to describe primary tooth emergence in an American Indian (AI) population during the first 36 mo of life to compare 1) patterns of emergence between male and female children and 2) tooth emergence between these AI children and other U.S. ethnic groups. Data were derived from a birth cohort of 239 AI children from a Northern Plains tribe participating in a longitudinal study of early childhood caries, with examination data at target ages of 8, 12, 16, 22, 28, and 36 mo of age (±1 mo). Patterns of emergence in AI children were characterized and sex comparisons accomplished with interval-censored survival methodology. Numbers of erupted teeth in AI children at each age were compared via Kruskal-Wallis tests against those in children of the same age, as drawn from a cross-sectional study of dental caries patterns in Arizona; these comparisons were based on the dental examinations of 547 White non-Hispanic and 677 Hispanic children. Characterization of time to achievement of various milestones-including emergence of the anterior teeth, the first molars, and the complete primary dentition-provided no evidence of sex differences among AI children. AI children had significantly more teeth present at 8 mo (median, 3) than either White non-Hispanic (P < 0.0063) or Hispanic (P < 0.0001) children (median, 2 each). This was also true at 12 mo (P < 0.001; medians, 8 vs. 6 and 7, respectively) and 16 mo (P < 0.001; medians, 12 vs. 11 each). Less pronounced differences were seen at 22 mo (P < 0.0001). White non-Hispanic and Hispanic children did not differ at any time considered (P > 0.05). These results provide evidence of earlier tooth emergence in AI children than in the other 2 ethnicities. Although the underlying etiology of the severity of early childhood caries in AI children is likely to be multifactorial, earlier tooth emergence may be a contributing factor. Knowledge Transfer Statement: The findings of this study have practical implications for practitioners providing childhood oral health care to ethnic groups with early tooth emergence. It may be important to provide parents with information on toothbrushing, dentist visits, and other practices supportive of good oral health as early as possible to protect their children's primary dentition.

Performance of two different digital evaluation systems used for assessing pre-clinical dental students' prosthodontic technical skills.

INTRODUCTION: Proper integration of newly emerging digital assessment tools is a central issue in dental education in an effort to provide more accurate and objective feedback to students. The study examined how the outcomes of students' tooth preparation were correlated when evaluated using traditional faculty assessment and two types of digital assessment approaches. Specifically, incorporation of the Romexis Compare 2.0 (Compare) and Sirona prepCheck 1.1 (prepCheck) systems was evaluated. Additionally, satisfaction of students based on the type of software was evaluated through a survey. MATERIAL AND METHODS: Students in a second-year pre-clinical prosthodontics course were allocated to either Compare (n = 42) or prepCheck (n = 37) systems. All students received conventional instruction and used their assigned digital system as an additional evaluation tool to aid in assessing their work. Examinations assessed crown preparations of the maxillary right central incisor (#8) and the mandibular left first molar (#19). All submissions were graded by faculty, Compare and prepCheck. RESULTS: Technical scores did not differ between student groups for any of the assessment approaches. Compare and prepCheck had modest, statistically significant correlations with faculty scores with a minimum correlation of 0.3944 (P = 0.0011) and strong, statistically significant correlations with each other with a minimum correlation of 0.8203 (P < 0.0001). A post-course student survey found that 55.26% of the students felt unfavourably about learning the digital evaluation protocols. A total of 62.31% felt favourably about the integration of these digital tools into the curriculum. CONCLUSIONS: Comparison of Compare and prepCheck showed no evidence of significant difference in students' prosthodontics technical performance and perception.

Phenotype-genotype correlations of facial width and height proportions in patients with Class II malocclusion.

OBJECTIVES: To characterize soft-tissue facial height and width variation in Class II malocclusion and test for correlations with genes HMGA2, AJUBA, and ADK. SETTING AND SAMPLE POPULATION: Nine facial proportions were estimated from 2D frontal repose photographs of 330 Caucasian adults with Class II malocclusion. MATERIAL AND METHODS: After adjustments for age and gender, the facial proportions were submitted to a principal component analyses (PCA). The most meaningful phenotypic variations were correlated with SNPs rs7924176 (ADK), rs17101923 (HMGA2), and rs997154 (AJUBA) genotyped in 106 individuals. RESULTS: Principal component analyses resulted in four principal components (PCs), which explained 75% of total variation. PC1 captured variation in the intercanthus distance and explained 28% of total variation. PC2 explained 21% of the variations in facial taper and facial index. PC3 explained 14% and reflected variations in the vertical dimension of the lower face. PC4 explained 12% and captured variations in distance between the eyes, width of the commissures, and the length of the superior aspect of the lower face height corresponding to the vertical dimension of the philtrum of the upper lip. A suggestive association (p<0.05) was observed between PC4 and rs997154 corroborating the role of AJUBA in variation of facial dimensions. CONCLUSION: 2D frontal photographs can be used to derive quantitative measures of soft-tissue phenotypes that are of clinical relevance. The methods described are suitable for discovery and replication of associations between genotypes and malocclusion phenotypes.

Sphingoid bases are taken up by Escherichia coli and Staphylococcus aureus and induce ultrastructural damage.

Sphingoid bases found in the outer layers of the skin exhibit antimicrobial activity against gram-positive and gram-negative bacteria. We investigated the uptake of several sphingoid bases by Escherichia coli and Staphylococcus aureus, and assessed subsequent ultrastructural damage. E. coli and S. aureus were incubated with D-sphingosine, dihydrosphingosine, or phytosphingosine at ten times their MIC for 0.5 and 4 h, respectively, to kill 50% of viable bacteria. Treated bacterial cells were immediately prepared for SEM, TEM, and analyzed for lipid content by QTLC. E. coli and S. aureus treated with sphingoid bases were distorted and their surfaces were concave and rugate. Significant differences were observed in the visual surface area relative to controls for both E. coli and S. aureus when treated with dihydrosphingosine and sphingosine (p < 0.0001) but not phytosphingosine. While sphingoid base-treated S. aureus exhibited disruption and loss of cell wall and membrane, E. coli cytoplasmic membranes appeared intact and the outer envelope uncompromised. Both E. coli and S. aureus cells contained unique internal inclusion bodies, likely associated with cell death. QTLC demonstrated extensive uptake of sphingoid bases by the bacteria. Hence, sphingoid bases induce both extracellular and intracellular damage and cause intracellular inclusions that may reflect lipid uptake.