Protein Analysis of Sapienic Acid-Treated Porphyromonas gingivalis Suggests Differential Regulation of Multiple Metabolic Pathways.

UNLABELLED: Lipids endogenous to skin and mucosal surfaces exhibit potent antimicrobial activity against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Our previous work demonstrated the antimicrobial activity of the fatty acid sapienic acid (C(16:1Δ6)) against P. gingivalis and found that sapienic acid treatment alters both protein and lipid composition from those in controls. In this study, we further examined whole-cell protein differences between sapienic acid-treated bacteria and untreated controls, and we utilized open-source functional association and annotation programs to explore potential mechanisms for the antimicrobial activity of sapienic acid. Our analyses indicated that sapienic acid treatment induces a unique stress response in P. gingivalis resulting in differential expression of proteins involved in a variety of metabolic pathways. This network of differentially regulated proteins was enriched in protein-protein interactions (P = 2.98 × 10(-8)), including six KEGG pathways (P value ranges, 2.30 × 10(-5) to 0.05) and four Gene Ontology (GO) molecular functions (P value ranges, 0.02 to 0.04), with multiple suggestive enriched relationships in KEGG pathways and GO molecular functions. Upregulated metabolic pathways suggest increases in energy production, lipid metabolism, iron acquisition and processing, and respiration. Combined with a suggested preferential metabolism of serine, which is necessary for fatty acid biosynthesis, these data support our previous findings that the site of sapienic acid antimicrobial activity is likely at the bacterial membrane. IMPORTANCE: P. gingivalis is an important opportunistic pathogen implicated in periodontitis. Affecting nearly 50% of the population, periodontitis is treatable, but the resulting damage is irreversible and eventually progresses to tooth loss. There is a great need for natural products that can be used to treat and/or prevent the overgrowth of periodontal pathogens and increase oral health. Sapienic acid is endogenous to the oral cavity and is a potent antimicrobial agent, suggesting a potential therapeutic or prophylactic use for this fatty acid. This study examines the effects of sapienic acid treatment on P. gingivalis and highlights the membrane as the likely site of antimicrobial activity.

Factors Associated with Reevaluation of the Stepwise Excavation Procedure: An 8-Year Retrospective Study.

Although the stepwise excavation procedure (SWP) has been shown to be an effective caries treatment technique, studies reporting its application outside of controlled clinical trials are limited. We performed a retrospective study from patient record data to assess the proportion of patients who had an SWP reevaluated within 18 months at The University of Iowa College of Dentistry (UICOD) between 2004 and 2012, and evaluated the association between different variables and this outcome. A total of 1,985 SWPs were performed in 1,326 patients, with 518 patients having had reevaluation within 18 months. Bivariate analysis and logistic regression modeling revealed strong associations between explanatory variables such as provider type, tooth type, patient age, number of recalls and the calendar year in which the SWP was done and reevaluation status. There was also evidence of association with dental insurance status. Other characteristics such as gender, distance traveled to the UICOD, number of surfaces treated and tooth arch did not show any significant association. In general, patients were more likely to have reevaluation when seen by faculty members or residents, the procedure was performed in molars/pre-molars, they were older, they had more recalls and were seen earlier in the study period. These results suggest that decisions to use SWP should consider patient demographics and treatment characteristics such as provider level, tooth type, patient age and number of recalls. The impact of treatment year may reflect program heterogeneity or temporal changes in external societal factors.

The roles of cutaneous lipids in host defense.

Lauric acid (C12:0) and sapienic acid (C16:1Δ6) derived from human sebaceous triglycerides are potent antimicrobials found at the human skin surface. Long-chain bases (sphingosine, dihydrosphingosine and 6-hydroxysphingosine) are also potent and broad-acting antimicrobials normally present at the skin surface. These antimicrobials are generated through the action of ceramidases on ceramides from the stratum corneum. These natural antimicrobials are thought to be part of the innate immune system of the skin. Exogenously providing these lipids to the skin may provide a new therapeutic option, or could potentially provide prophylaxis in people at risk of infection. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Comparison of pro-inflammatory cytokines and bone metabolism mediators around titanium and zirconia dental implant abutments following a minimum of 6 months of clinical function.

OBJECTIVES: Dental implant abutments are fundamental prosthetic components within dentistry that require optimal biocompatibility. The primary aim of this cross-sectional study was to preliminarily assess differences in the pro-inflammatory cytokine and bone metabolism mediator protein expression in the peri-implant crevicular fluid (PICF) adjacent to transmucosal abutments. MATERIAL AND METHODS: Abutments were fabricated from either titanium or zirconia in patients previously receiving single-tooth implant therapy. All subjects sampled in this study had an identical implant system and implant-abutment connection. Participants (n = 46) had an average time of clinical function for 22 months (6.2-72.8 months, ±SD 17 months) and received a clinical and radiographic examination of the implant site at the time of PICF sampling using a paper strip-based sampling technique. Cytokine, chemokine, and bone metabolism mediator quantities (picograms/30 s) were determined using a commercial 22-multiplexed fluorescent bead-based immunoassay instrument. A total of 19 pro-inflammatory cytokines and seven bone metabolism mediators were evaluated. RESULTS: Multivariable analyses provided no evidence of a group (titanium or zirconia), gender, or age effect with regard to the expression of pro-inflammatory mediators evaluated. Significant (P = 0.022) differences were observed for the bone mediator leptin, with titanium abutments demonstrating significantly elevated levels in comparison with zirconia. Osteopontin demonstrated a significant (P = 0.0044) correlation with age of the subjects. CONCLUSIONS: No significant differences in pro-inflammatory cytokine or bone metabolism mediator profiles were observed biochemically, with the exception of leptin, for the abutment biomaterials of titanium or zirconia The molecular PICF findings support the observed clinical biocompatibility of both titanium and zirconia abutments.

Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria.

There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity--the sphingoid bases D-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid--against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. D-sphingosine (MBC range, 0.3 to 19.6 µg/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 µg/ml), and phytosphingosine (MBC range, 3.3 to 62.5 µg/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 µg/ml). Sapienic acid (MBC range, 31.3 to 375.0 µg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 µg/ml). Lauric acid (MBC range, 6.8 to 375.0 µg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 µg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection.

Clinical Versus Radiographic Caries Diagnosis in Primary Tooth Approximal Surfaces.

Purpose: The purpose of this study was to compare approximal carious lesions in dentin diagnosed by clinical examination with those diagnosed radiographically in high caries-risk children. Methods: Eighty-four Amish two- to 11-year-olds were evaluated clinically by calibrated examiners using standard epidemiological criteria and radiographically using standard criteria as part of baseline examinations for a two-year pilot clinical trial. Approximal carious surfaces diagnosed by clinical examination were compared to those diagnosed radiographically to determine the number of lesions misdiagnosed by clinical examination alone. Comparisons between the number of lesions detected by clinical exam and radiographic exam were made using McNemar's test. Results: Among 124 anterior approximal tooth surfaces, clinical examination alone identified 61 lesions (49.2 percent), while radiograph examination identified 72 lesions (58.1 percent); thus, nine percent of lesions were misdiagnosed by clinical examination alone. For the 412 posterior approximal tooth surfaces included in the study, 101 lesions (24.5 percent) were identified by clinical examination, whereas 229 lesions (55.6 percent) were identified via radiographic examination. Thus, 128 (31.1 percent) were misdiagnosed by clinical examination alone. Conclusions: Clinical examinations without radiographs significantly underestimate caries prevalence. Therefore, the use of radiographs should be encouraged in epidemiological studies and clinical trials.

Intraoral Camera Use in a Dental School Clinic: Evaluations by Faculty, Students, and Patients.

The aims of this study were to assess the perceptions of dental students, faculty members, and patients about the benefits and pitfalls of intraoral camera use and to compare the completion rate of treatment planned posterior crowns with and without intraoral camera use in a predoctoral dental clinic. From July 2016 to June 2017, all 60 fourth-year dental students at one U.S. dental school were encouraged to use the intraoral camera in treatment planning with patients in the school clinic. Perceptions of the students, their patients, and the faculty members supervising the treatment planning were assessed with a survey at the end of the treatment planning appointment. The completion rate of treatment planned posterior crowns was determined by recalling all posterior teeth that were treatment planned for a single unit crown at a specific period of time compared to the number of the same crowns completed for the same patients at a specific period of time, using the electronic health record, with and without camera use. Of the 60 students, 51 completed 198 surveys (85% response rate); 35 faculty members completed 64 surveys, and 202 patients completed one survey each (response rates for those groups could not be calculated). The survey results suggested that the students, faculty, and patients viewed intraoral camera use in a positive way. However, faculty perceptions were a little lower than those of patients and students, and a significant number of faculty members were neutral. The completion rate of posterior planned crowns was significantly higher (p=0.0005) when intraoral cameras were used to present images to patients than when cameras were not used. In this study, intraoral camera use in a predoctoral clinic was perceived positively by students and patients but more neutrally by faculty, and it increased the completion rate of planned posterior crowns.

Iowa nursing facility oral hygiene (INFOH) intervention: A clinical and microbiological pilot randomized trial.

PURPOSE/AIM: The aim of this pilot study was to evaluate feasibility and gather initial data for a definitive study to test the clinical and microbiological effectiveness of a nursing facility (NF) customized oral hygiene protocol, intended to be delivered by dental hygienists and NF personnel. MATERIALS AND METHODS: A convenience sample of 8 Eastern Iowa NFs was recruited, and each NF was assigned to one of three intervention groups: (1) control (current oral hygiene practice), (2) educational program only, and (3) educational program plus 1% chlorhexidine varnish monthly application. Demographic information, systemic health data, patient centered data, oral health data, and microbiology samples were collected at baseline and after 6 months. RESULTS: Recruitment response rates were 21% for NFs and 23% for residents. A total of 81 residents were examined at baseline and of those, 49 were examined at 6 months (39.5% attrition). There were no statistically or clinically significant differences among the intervention groups at 6 months for any of the recorded clinical or microbiological outcomes. CONCLUSIONS: Recruitment and retention posed a significant challenge to this trial, even with a relatively short observation period. Results from this pilot study did not encourage further investigation of this customized oral hygiene protocol.

Genotypic characterization and comparison of Streptococcus mutans in American Indian and Southeast Iowa children.

Early childhood caries is a complex health care issue that has a multifactorial etiology. One aspect of this etiology is the colonization and propagation of acidogenic bacteria at an early age. There have been several bacterial species associated with caries but 1 common species is Streptococcus mutans. Here, we describe genotypic diversity and commonality of Streptococcus mutans recovered from children representing 2 groups with similar socioeconomic demographics: a Northern Plains American Indian Tribe and a Southeast Iowa population. Forty 36-month-old American Indian children were selected from a cohort of 239 mothers and children, and forty 2- to 5-year-old children from Southeast Iowa were selected to compare the genotypic profiles of Streptococcus mutans recovered from each child's plaque. S. mutans isolates were selected from whole mouth plaque samples; DNA was extracted and amplified via AP-PCR to show specific genotype patterns. These patterns were compared with GelComparIIv6.5 gel analysis software. We found 18 distinct genotypes from 524 isolates; 13 of which were common between the 2 communities. Five genotypes were unique to only the American Indian children while the Southeast Iowa children harbored no unique genotypes. Although the American Indian children had some genotypes that were not present in the Southeast Iowa children, these were not widely distributed among the community. Furthermore, the levels of genotypic diversity and commonality were similar between the 2 populations. This study sets the groundwork for a comprehensive comparison of genotypes and caries among larger subsections of both populations.

Understanding and evaluating meta-analysis.

BACKGROUND: Meta-analysis refers to statistical methodology used to combine data from many studies to obtain an overall assessment of disease risk or treatment outcomes. In this article, the authors review basic methods, interpretation, and limitations of meta-analysis. METHODS: Investigators use meta-analysis approaches to combine data from available studies to obtain an answer to a specific question. An investigator uses a fixed model if there is homogeneity among the combined studies and a random-effects model if there is heterogeneity. The random-effects model results in wider confidence limits and more conservative estimates of overall results. A meta-analysis can be biased because studies with negative results (no differences in treatment outcomes) are less likely to be published (publication bias). RESULTS: A meta-analysis should include a well-specified and reproducible set of procedures, including description of data abstraction procedures, attempts to include unpublished studies, and appropriate statistical analysis that includes thorough consideration of heterogeneity and potential bias. CONCLUSIONS: Meta-analysis cannot correct shortcomings of existing studies or data. However, if potential pitfalls are recognized, meta-analysis can be a useful tool for summarizing existing studies, providing a means to address conflicting reports. Meta-analysis can lead to increased precision, providing greater power to detect existing relationships or treatment effects. Furthermore, meta-analysis may make it possible to address questions that cannot be answered by means of individual studies. PRACTICAL IMPLICATIONS: Meta-analysis provides an objective, quantitative synthesis of available studies but needs to be understood and assessed critically by those who use it to assess risk or make treatment decisions.

Impact of Digital Tooth Preparation Evaluation Technology on Preclinical Dental Students' Technical and Self-Evaluation Skills.

The aim of this study was to evaluate the effect of digital tooth preparation imaging and evaluation technology on dental students' technical abilities, self-evaluation skills, and the assessment of their simulated clinical work. A total of 80 second-year students at one U.S. dental school were assigned to one of three groups: control (n=40), E4D Compare (n=20), and Sirona prepCheck (n=20). Students in the control group were taught by traditional teaching methodologies, and the technology-assisted groups received both traditional training and supplementary feedback from the corresponding digital system. Three outcomes were measured: faculty technical score, self-evaluation score, and E4D Compare scores at 0.30 mm tolerance. Correlations were determined between the groups' scores from visual assessment and self-evaluation and between the visual assessment and digital scores. The results showed that the visual assessment and self-evaluation scores did not differ among groups (p>0.05). Overall, correlations between visual and digital assessment scores were modest though statistically significant (5% level of significance). These results suggest that the use of digital tooth preparation evaluation technology did not impact the students' prosthodontic technical and self-evaluation skills. Visual scores given by faculty and digital assessment scores correlated moderately in only two instances.

Timing of primary tooth emergence among U.S. racial and ethnic groups.

OBJECTIVES: To compare timing of tooth emergence among groups of American Indian (AI), Black and White children in the United States at 12 months of age. METHODS: Data were from two sources - a longitudinal study of a Northern Plains tribal community and a study with sites in Indiana, Iowa and North Carolina. For the Northern Plains study, all children (n = 223) were American Indian, while for the multisite study, children (n = 320) were from diverse racial groups. Analyses were limited to data from examinations conducted within 30 days of the child's first birthday. RESULTS: AI children had significantly more teeth present (Mean: 7.8, Median: 8.0) than did Whites (4.4, 4.0, P < 0.001) or Blacks (4.5, 4.0, P < 0.001). No significant differences were detected between Black and White children (P = 0.58). There was no significant sex difference overall or within any of the racial groups. CONCLUSIONS: Tooth emergence occurs at a younger age for AI children than it does for contemporary White or Black children in the United States.

Factors associated with dental caries in a group of American Indian children at age 36 months.

OBJECTIVES: Early childhood caries (ECC) is rampant among American Indian children, but there has been relatively little study of this problem. This article reports on risk factors for caries for a group of American Indian children at age 36 months as part of a longitudinal study. METHODS: Pregnant women from a Northern Plains Tribal community were recruited to participate in a longitudinal study of caries and caries risk factors. Standardized dental examinations were completed on children, and questionnaires were completed by mothers at baseline and when children were 4, 8, 12, 16, 22, 28, and 36 months of age. Examinations were surface-specific for dental caries, and the questionnaires collected data on demographic, dietary, and behavioral factors. Nonparametric bivariate tests and logistic regression models were used to identify risk factors for caries at 36 months, and negative binomial regression was used to identify factors related to caries severity (dmf counts). RESULTS: Among the 232 children, and caries prevalence for cavitated lesions was 80%, with an additional 15% having only noncavitated lesions. The mean dmfs was 9.6, and of the total dmfs, nearly 62% of affected surfaces were decayed, 31% were missing, and 7% were filled. Logistic regression identified higher added-sugar beverage consumption, younger maternal age at baseline, higher maternal DMFS at baseline, and greater number of people in the household as significant (P < 0.05) risk factors. Negative binomial regression found that only maternal DMFS was associated with child dmf counts. CONCLUSIONS: By the age of 36 months, dental caries is nearly universal in this population of American Indian children. Caries risk factors included sugared beverage consumption, greater household size, and maternal factors, but further analyses are needed to better understand caries in this population.

Acidogenicity and acid tolerance of Streptococcus oralis and Streptococcus mitis isolated from plaque of healthy and incipient caries teeth.

BACKGROUND: Non-mutans low pH oral streptococci are postulated to contribute to caries etiology. OBJECTIVE: This study was undertaken to investigate whether the acidogenicity and acid tolerance of clinical strains of Streptococcus oralis and Streptococcus mitis correlate with health or early-stage enamel caries. DESIGN: S. oralis and S. mitis were isolated from plaque samples taken from the occlusal surfaces of second molars sampled at two different visits 4 years apart. All sites were sound at Visit 1; subjects were segregated into one of three groups based on the status of the site at Visit 2 and caries elsewhere in the dentition. Strains of S. oralis and S. mitis were evaluated for acidogenicity and acid tolerance, and the results correlated with the clinical status of the sites from which they were isolated. Mutans streptococci (MS) isolated from the plaque samples were also quantified, and the presence or absence of growth on pH 5.5 media or on media selective for bifidobacteria was recorded. RESULTS: No significant positive correlations were found between the acidogenicity properties of the S. oralis and S. mitis clones and caries at either visit. Similar results were obtained for acid tolerance of S. oralis clones but were inconclusive for S. mitis clones. A statistically significant positive correlation between MS levels and caries (or future caries) was evident at both visits, but there were no statistical correlations with the growth on pH 5.5 media or media selective for bifidobacteria. CONCLUSIONS: The low pH potential likely varies considerably among oral streptococcal species and is least likely to be found among strains of S. mitis. Accordingly, the concept and constitution of 'low pH streptococci' may need to be re-evaluated.

Evidence-Based Practice Knowledge, Perceptions, and Behavior: A Multi-Institutional, Cross-Sectional Study of a Population of U.S. Dental Students.

The aim of this study was to help inform faculty and curriculum leaders in academic dental institutions about the knowledge, skills, perceptions, and behavior of an institutionally diverse population of dental students with respect to evidence-based practice (EBP). A survey utilizing the validated Knowledge, Attitudes, Access, and Confidence Evaluation instrument developed by Hendricson et al. was conducted in 2012 with fourth-year dental students at seven geographically dispersed U.S. dental schools. The survey addressed elements of EBP knowledge, attitudes toward EBP, behavior in accessing evidence, and perceptions of competence in statistical analysis. A total of 138 students from the seven schools participated. A slight majority of these students correctly responded to the knowledge of critical appraisal questions. While the students demonstrated positive attitudes about EBP, they did not report high levels of confidence in their critical appraisal skills. The findings also showed that the students accessed various sources of evidence with differing frequencies. The most frequently accessed resources were colleagues, the Internet (excluding Cochrane Database of Systematic Reviews), and textbooks. The results of this study help to identify areas for improvement in EBP education in order to advance dental students' preparation to become evidence-based practitioners.

Effect of Computer-Assisted Learning on Students' Dental Anatomy Waxing Performance.

The aim of this study was to evaluate the impact of computer-assisted learning on first-year dental students' waxing abilities and self-evaluation skills. Additionally, this study sought to determine how well digital evaluation software performed compared to faculty grading with respect to students' technical scores on a practical competency examination. First-year students at one U.S. dental school were assigned to one of three groups: control (n=40), E4D Compare (n=20), and Sirona prepCheck (n=19). Students in the control group were taught by traditional teaching methodologies, and the technology-assisted groups received both traditional training and supplementary feedback from the corresponding digital system. Five outcomes were measured: visual assessment score, self-evaluation score, and digital assessment scores at 0.25 mm, 0.30 mm, and 0.35 mm tolerance. The scores from visual assessment and self-evaluation were examined for differences among groups using the Kruskal-Wallis test. Correlation between the visual assessment and digital scores was measured using Pearson and Spearman rank correlation coefficients. At completion of the course, students were asked to complete a survey on the use of these digital technologies. All 79 students in the first-year class participated in the study, for a 100% response rate. The results showed that the visual assessment and self-evaluation scores did not differ among groups (p>0.05). Overall correlations between visual and digital assessment scores were modest though statistically significant (5% level of significance). Analysis of survey responses completed by students in the technology groups showed that profiles for the two groups were similar and not favorable towards digital technology. The study concluded that technology-assisted training did not affect these students' waxing performance or self-evaluation skills and that visual scores given by faculty and digital assessment scores correlated moderately.

Genotypic characterization of initial acquisition of Streptococcus mutans in American Indian children.

BACKGROUND: Severe-early childhood caries (S-ECC) is one of the most common infectious diseases in children and is prevalent in lower socio-economic populations. American Indian children suffer from the highest levels of S-ECC in the United States. Members of the mutans streptococci, Streptococcus mutans, in particular, are key etiologic agents in the development of caries. Children typically acquire S. mutans from their mothers and early acquisition is often associated with higher levels of tooth decay. METHODS: We have conducted a 5-year birth cohort study with a Northern Plains Tribe to determine the temporality and fidelity of S. mutans transmission from mother to child in addition to the genotypic diversity of S. mutans in this community. Plaque samples were collected from 239 mother/child dyads at regular intervals from birth to 36 months and S. mutans were isolated and genotyped by arbitrarily primed-polymerase chain reaction (AP-PCR). RESULTS: Here we present preliminary findings from a subset of the cohort. The focus for this paper is on initial acquisition events in the children. We identified 17 unique genotypes in 711 S. mutans isolates in our subset of 40 children, 40 mothers and 14 primary caregivers. Twelve of these genotypes were identified in more than one individual. S. mutans colonization occurred by 16 months in 57.5% of the children and early colonization was associated with higher decayed, missing and filled surface (DMFS) scores (p=0.0007). Children colonized by S. mutans shared a common genotype with their mothers 47.8% of the time. While multiple genotypes were common in adults, only 10% of children harbored multiple genotypes. CONCLUSION: These children acquire S. mutans at an earlier age than the originally described 'window of infectivity' and often, but not exclusively, from their mothers. Early acquisition is associated with both the caries status of the children and the mothers.