Objectives: To evaluate the influence of five different displays on the diagnosis of artificial caries-like lesions on restored and unrestored tooth surfaces. Materials & Methods: 60 extracted human teeth (30 premolars and 30 molars) were selected. All molars had class II cavities prepared and restored. Half of the premolars and molars were randomly selected and a 7mm² area was exposed to a demineralizing solution for 120 days. Phantoms with four teeth (two premolars and two molars) were created. Periapical radiographs were obtained on RVG 6100 digital sensor (Kodak Dental Systems, New York, USA). The images were evaluated under subdued lighting on five viewing displays (Barco MDNC-3321, NEC Wide, Apple iPad Pro, Microsoft Surface Pro 4 and Dell flat panel monitor) by three observers using a five-point rating scale. Sensitivity (Sn), specificity (Sp), accuracy (Ac) and Receiver Operating Characteristic (ROC) curves and their areas under the curves (AUC) were calculated and compared by Analysis of variance and post-hoc Tukey test. Intraobserver and interobserver agreement were accomplished after a three month interval observational.. The observer agreement was evaluated with the Cohen’s kappa test. Results: Even though the tablets slightly improved accuracy over the medical monitors, there was no statistically significant difference in sensitivity, specificity, accuracy or AUC among the five monitors when the same tooth group was considered (p< 0.05) with the exception of the iPad Pro which had a specificity p-value of 0.014 when comparing the two materials within the iPad Pro. Conclusion: There is no perceivable disadvantage to utilizing a higher resolution tablet viewing platform for plane images. No advantage to the medical grade monitors over the tablets or the consumer monitor. Both tablets improved detection accuracy on the unrestored premolars. However further evaluation especially in a clinical lighting setting is warranted to evaluate a displays impact on observer performance within common clinical practice lighting parameters.

My PhD projects were secondary analyses of data from a prospective study conducted at the University of Alabama at Birmingham. Two cohorts of low socioeconomic status, African-American children from Perry County, Alabama, were invited to participate. Children in the 1st Cohort (Cohort 1, n=98) were approximately six years old at baseline and followed for 6 years, while children in the 2nd Cohort (Cohort 2, n=95) were approximately one-year-old at baseline and followed for five years. For the first dissertation project, the prevalence and incidence of dental decay were assessed for children in Cohort 1. The findings of this report showed that 60-70% of the children had dental decay experience at each of the six annual exams. Approximately a third of the children had additional new tooth decay from age 6 to age 12. For the second project, risk factors for time to dental decay occurrence were assessed using a relatively new analytic approach which allowed the use of time-dependent risk factors for children in Cohort 1. This was the first time for this analytic approach to be used in the dental literature, although it is widely used in medical research. The merit of using this technique was that, since dental decay risk factors can change with time, the value of the risk factor was allowed to change over time. The second project showed that about 29% of the children had their first permanent tooth decay event during the six-year follow-up. Final results showed that greater consumption of water, milk and 100% juice were associated with lower dental decay hazards, while greater consumption of added-sugar juice was associated with greater hazard of having an event. The third PhD project was designed to assess the patterns of and the relationship between initial Mutans Streptococci detection and dental caries experience occurrence in African-American pre-school children with mean age of 1 year at baseline. The third project dealt with the MS variable as a “time-dependent variable”, using a statistical analysis called “Extended Cox hazards modeling”. To the knowledge of the author, this is the first published study which has used this relatively new analytic approach to assess the complex relationship between MS detection and dental caries experience. In addition, in the third project, the behavioral risk factors for having a positive salivary MS test were assessed. This study found that median MS acquisition survival (when 50% of the children had positive salivary MS test) was 2 years and mean survival time was 2.09±0.09 among African-American children who had valid MS acquisition tests (n=99). Approximately 23% of the children did not have any positive salivary MS test by age 4 years. Multivariable analysis showed that not having a positive salivary MS test at any of the study exams was associated with having acute illness in the previous 6 months and being recruited into the study before 10 months of age. Results of extended Cox proportional hazards modeling showed a significant relationship between having a caries experience event at any given time during the follow-up period and having a positive salivary MS test at any point in time (HR=2.25, 95% CI 1.06-4.75).

Significant efforts have been undertaken in medicine to identify hospital and primary care service areas (eg, the Dartmouth Atlas of Health Care) using patient origin information. Similar research in dentistry is nonexistent. The goal of this dissertation was to develop and refine methods of defining dentist service areas (DSAs) using dental insurance claims. These service areas were then used as spatial units of analysis in studies that examined relationships between utilization of oral health services, dentist workforce supply, and service area characteristics. Enrollment and claims data were obtained from the Iowa Medicaid program for children and adolescents ages 3-18 years during calendar years 2008 through 2010. The first study described rates of treatment by orthodontists in children ages 6-18 years. Orthodontic DSAs were identified by small area analysis in order to examine regional variability in utilization. The overall rate of utilization was approximately 3%; 19 DSAs were delineated. Interestingly, children living in small towns and rural areas were significantly more likely to have received orthodontic services than those living in metropolitan and micropolitan areas. The second study identified 113 DSAs using claims submitted by primary care dentists (ie, general and pediatric dentists). Characteristics of these primary care DSAs were then compared with counties. Localization of care was used as a measure of how well each region approximated a dental market area. Approximately 59% of care received by Medicaid-enrolled children took place within their assigned service area versus 52% of care within their county of residence. Hierarchical logistic regression was used in the final study to examine the influence of spatial accessibility and the importance of place on the receipt of preventive dental visits among Medicaid-enrolled children. Children living in urban areas were more likely to have received a visit than those living in more rural areas. Spatial accessibility assessed using measures of dentist workforce supply and travel cost did not appear to be a major barrier to care in this population. More studies are needed to explore the importance of spatial accessibility and other geographic barriers on access to oral health services. The methods used in this dissertation to identify service areas can be applied to other populations and offer an appropriate method for examining revealed patient preferences for oral health care.

No description available.

The prevalence of obesity is continually rising in developed countries like the United States. Based on the association between periodontitis and obesity and the relationship between periodontitis and peri-implantitis, it is important to understand the implications of obesity on peri-implant health. A potential relationship between obesity and peri-implant health has practical, biological and financial implications. The primary objective of this study was to determine the association between obesity as measured by the body fat indices (body mass index (BMI), waist circumference (WC), and body fat percent (fat %)) and the levels of inflammatory biomarkers in saliva. In addition, this study explored the correlations between the levels of these biomarkers in saliva versus their corresponding levels in peri-implant sulcular fluid (PISF) and gingival crevicular fluid (GCF) samples collected from the same subjects. Periodontal maintenance patients (N=73) were enrolled in this cross-sectional study. Anthropometric measurements (BMI, WC, and body fat %), intraoral assessment (full mouth plaque index, periodontal, and peri-implant comprehensive examinations) and unstimulated whole saliva samples were collected from the subjects. GCF and PISF were also collected. Levels of interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-10, IL-12(p40), IL-17α, tumor necrosis factor (TNF)-α, osteoprotegerin (OPG), letpin and C-reactive protein (CRP) in saliva, GCF and PISF were analyzed using multiplex immunoassays. Statistical analyses were performed to explore the correlations of interest. Data from 63 subjects were included in the analysis. No statistically significant correlations were noted between any of the body fat indices and any of the biomarkers measured in saliva (p>0.05 in all instances). A significant positive correlation was noted between salivary and GCF levels of IL-1α (r=0.29, p=0.0232), IL-8 (r=0.29, p=0.0207) and between saliva and PISF levels of leptin (r=0.32, p=0.0284). The employed linear model also revealed the significant impact of tooth brushing frequency on the salivary levels of IL-1α, IL-1β and TNF-α (p<0.05). Based on this cross-sectional study of 63 patients, I conclude that there was no statistically significant correlation noted between salivary inflammatory biomarkers and any of the obesity measures. However, the levels of key inflammatory markers in saliva strongly correlated with their corresponding levels in GCF/PISF. In addition, frequency of tooth brushing was also related to levels of certain biomarkers in GCF/PISF.

Periodontal disease is a chronic inflammation of the gingiva and periodontium that leads to progressive destruction and irreversible damage to the supportive structures of the teeth. It affects nearly half of the United States population and is a particular risk factor in adults older than 65 years of age. Oral microorganisms assemble in plaque as a polymicrobial biofilm and Porphyromonas gingivalis, an important secondary colonizer in oral biofilms, has been implicated in periodontal disease. Although the protective functions of various salivary molecules such as antimicrobial proteins have been delineated, lipids present in saliva and on the oral mucosa have been largely ignored and there is growing evidence that the role of lipids in innate immunity is more important than previously realized. In fact, recent studies suggest that sphingoid bases and fatty acids, which exhibit potent broad spectrum antimicrobial activity against a variety of bacteria and fungi, are likely important innate immune molecules involved in the defense against oral bacterial and fungal infections. However little is known about their spectrum of activity or mechanisms of action. In addition, the effects of these lipids that are endogenous to the oral cavity have not been explored against oral bacteria. In this study I hypothesized that oral mucosal and salivary lipids exhibit dose-dependent antimicrobial activity against P. gingivalis and alter cell morphology and metabolic events. To test this hypothesis, I first examined the effects of two fatty acids: sapienic acid and lauric acid, and three sphingoid bases: sphingosine, dihydrosphingosine, and phytosphingosine, against a variety of gram-positive and gram-negative bacteria including P. gingivalis. Using broth microdilution assays to determine minimum inhibitory and minimum bactericidal concentrations, I show that antimicrobial activity against bacteria is dose-dependent, lipid specific, and microorganism specific. Kill kinetics were also variable across each bacteria-lipid combination. Upon examination of select bacteria-lipid combinations via scanning and transmission electron microscopy, different morphologies were evident across all treatments, demonstrating differential activity of each lipid for a particular bacterium as well as for each bacterium across different lipids. In addition, all sphingoid bases and fatty acids were taken up and retained in association with P. gingivalis cells and could be extracted along with bacterial lipids and separated using thin layer chromatography. Using a combination of two-dimensional in-gel electrophoresis and Western blots followed by mass spectroscopy and n-terminus degradation sequencing, I show that sapienic-acid treatment induces a unique stress response in P. gingivalis, as evidenced by the ability of P. gingivalis to upregulate a set of proteins involved in fatty acid biosynthesis metabolism and energy production, protein processing, cell adhesion, and virulence. Finally, utilizing flow cytometry and confocal microscopy, I assessed the effects of oral antimicrobial lipids against a representative host cell and describe oral lipid concentrations that are both antimicrobial to P. gingivalis cells and non-cytotoxic to the representative host cells tested. Combined, these data strongly suggest that sphingoid bases and fatty acids found within the saliva and on oral mucosa likely do contribute to the innate antimicrobial activity of saliva, mucosal surfaces, and skin and this dose-dependent activity is both lipid specific and bacteria specific. This information adds to current knowledge of the innate functions of endogenous lipids in the oral cavity. With bacterial resistance to current antibiotics increasing, the exploration of new antimicrobial agents is important and these lipid treatments may be beneficial for prophylactic treatments or therapeutic intervention of infection by supplementing the natural immune function of endogenous lipids on skin and other mucosal membranes.

Sphingoid bases (sphingosine, dihydrosphingosine and phytosphingosine) have been recently found in the oral cavity where they may serve to fortify innate immunity against commensals and periodontal pathogens. In fact, sphingoid bases have potent antimicrobial activity against Gram- positive and Gram- negative bacteria including oral pathogens like Porphyromonas gingivalis. It is not known whether these lipids are cytotoxic or alter the chemokine and cytokine responses of human dendritic cells, a finding important to their future potential as a therapeutic for treatment of periodontal disease. Objectives: The objective of this study was to determine the effects of sphingoid bases on the cytotoxicity and cytokine responses of human myeloid dendritic cells. Methods: Dendritic cells were treated with sphingoid bases (0.2-80.0 μM) for 16 hours in the presence or absence of 0.02 μM hemagglutinin B, a nonfimbrial adhesin of P. gingivalis used as a pro-inflammatory stimulus. The cytotoxicity of the inocula and its ability to induce the production of chemokines and pro-inflammatory cytokines was determined after 16 hours. Results: Higher concentrations of sphingoid bases were cytotoxic (e.g., 40.0-80.0 μM), but physiologic concentrations of sphingoid bases (e.g., 0.2-20.0 μM) were not. At 5, 10, or 20 μM, sphingosine did not enhance or attenuate any HagB-induced IL-8, GM-CSF, MIP-1α, MIP-1β, or TNFα response of human myeloid dendritic cells. At 5 or 10 μM, neither phytosphingosine nor dihydrosphingosine enhanced or attenuated any HagB- induced IL-8, GM-CSF, MIP-1α, MIP-1β, or TNFα response of human myeloid dendritic cells. Conclusion: Sphingoid bases exhibit dose-dependent cytotoxicity and cytokine responses against human myeloid dendritic cells. But at physiologic concentrations sphingoid bases appear to be safe and efficacious at the doses needed to prevent or treat microbial infections in the oral cavity.

Chlorhexidine mouth rinses remove dental plaque from teeth, preventing dental caries, dental decay, and more serious systemic infections. Tooth discoloration due to extrinsic staining is the most prominent side effect of regular chlorhexidine use. Decreasing the concentration of chlorhexidine reduces staining area and severity. Staining can also be prevented and treated by tooth bleaching, a common cosmetic dental procedure that diminishes extrinsic staining by oxidizing chromagens adsorbed onto the tooth surface. In the proposed trial, common bleaching agents will be investigated for their efficacies in preventing chlorhexidine staining. Results of the trial could further the development of a chlorhexidine mouth rinse that is suitable for long term use.

Previous studies suggest that Medicaid-enrolled children have difficulties accessing dental care, which can lead to untreated dental disease, poor oral health, and compromised overall health status. While Medicaid-enrolled children with a chronic condition (CC) encounter additional barriers to dental care, most relevant studies on dental utilization fail to adopt risk adjustment methods. As such, the impact of CC status and CC severity on access to dental care for Medicaid-enrolled children is poorly understood. The main objectives of this dissertation were to: 1) compare dental utilization for Medicaid-enrolled children with and without a CC; 2) assess the relationship between CC severity and dental utilization; and 3) identify the other factors associated with dental utilization. The 3M Clinical Risk Grouping (CRG) Methods were applied to enrollee-level data from the Iowa Medicaid Program (2003-2008) to identify children with and without a CC and to classify children with a CC into a CC severity level. Three outcome measures were developed: 1) access to an annual dental visit; 2) use of dental services under general anesthesia (GA); and 3) time to the first dental visit after initial enrollment into the Medicaid program. We used multiple variable logistic regression models and survival analytic techniques to test our study hypotheses. Compared to Medicaid-enrolled children without a CC, those with a CC were more likely to have had an annual dental visit and earlier first dental visits. Having a CC was an important determinant of dental utilization under GA for older but not for younger Medicaid-enrolled children. In terms of CC severity, Medicaid-enrolled children with more severe CCs were less likely to have had an annual dental visit and more likely to have utilized dental services under GA. CC severity was not associated with the rate at which the first dental visit took place. Not residing in a dental Health Professional Shortage Area, previous use of dental care, and previous utilization of primary medical care were all positively associated with dental utilization. Identifying and understanding the determinants of access to dental care is an important first step in developing clinical interventions and policies aimed at improving access to dental care for all Medicaid-enrolled children. Future work should focus on identifying the socio-behavioral determinants of as well as the clinical outcomes associated with access to dental services for vulnerable children.

Background P. gingivalis, a non-motile, rod-shaped, anaerobic, Gram-negative bacterium is one of the principal sources of periodontal disease. It possesses a number of potential virulence factors thought to be important in the disease process including 5 hemagglutinins (Hag). One of these is HagB. It is a well characterized nonfimbrial adhesin expressed on the surface of P. gingivalis. HagB is very pro-inflammatory and induces robust chemokine and cytokine responses in vitro and in vivo. Since the chemokine and cytokine responses seen from single cells grown in tissue culture often are not representative of the chemokine and cytokine profiles seen in clinical samples or biopsy specimens, we devised a co-culture model of keratinocytes, dendritic cells, and T-cells to test the hypothesis that chemokine and cytokine responses from co-cultured cells would be more representative of responses seen in clinical samples from individuals with periodontal disease than single cell models. Methods and materials HagB was prepared by cloning hagb of P. gingivalis (1.4 kb) into the vector pQE31 (QIAGEN Inc., Valencia, CA); expressed in E. coli M15(pREP4)pQE31-TX1; and isolated from E. coli lysates by affinity chromatography using a Ni-charged resin (Profinity IMAC Resin, BioRad, Hercules, CA) and examined by SDS-PAGE. Co-culture models were treated with 10 µg/ml HagB (Test) or 10 µg/ml HagB diluent (Control). At 64 hours the supernatants were collected. Chemokine and cytokine biomarkers GM-CSF, CCL3 (MIP-1α), CCL4 (MIP-1β), CCL5 (RANTES), IL-1α, IL-6, IL-8, TNFα, IL-12(p40), and VEGF responses were determined using Milliplex immunoassays. HagB responses were corrected by subtracting the constitutive responses detected in supernatants incubated with HagB diluent. Statistical differences among groups were determined on Log10 transformed biomarker concentration using JMP 10 (version 10.0, SAS, CAR; NC). Results Buffers (e.g. HagB diluent) did not induce a chemokine or cytokine response, however there was a gradual increase in chemokine and cytokine responses from cells at 64 hours. These were subtracted from HagB induced responses. Responses generally fell in 2 groups; in one group containing VEGF, IL-12(p40), IL-6, RANTES and GM-CSF, there were no significant differences among groups (p>0.05). In another group containing IL-1α, IL-8, MIP-1α, MIP-1β and TNF-α, there were significant differences among groups (p< 0.05). Interestingly these resulting responses fell in 2 categories- GM-CSF, IL-12, IL-1α, IL-6 were less than 25pg/ml and IL-8, MIP-1α, MIP-1β, RANTES, TNFα and VEGF were more than 25pg/ml. Some responses were driven by a particular cell type e.g. GM-CSF produced by dendritic cells, RANTES produced by T- cells and VEGF produced by T cells. There were similar responses in HagB-induced IL-8, MIP-1β, MIP-1α and TNFα responses by dendritic cells + keratinocytes and dendritic cells + keratinocytes + T cells. Conclusions Co-culture models can more realistically produce chemokine and cytokine responses to agonists than individual cultures of cells, which is important for predicting and assessing novel therapeutic treatments of periodontal disease.