David R Drake

• University of Iowa

Objectives: To determine if non-mutans low-pH streptococci are present in high proportions in dental plaque prior to the acquisition of a cariogenic plaque microbiota and diagnosis of caries. Methods: Children of 1 to 3 years of age, with no history of dental caries, were followed for 18 months with pooled plaque samples obtained at baseline and 6...

Objectives: The use of computer-aided design and computer-aided manufacturing technology has enabled the precise fabrication of restorations. Zirconia has emerged as an important material used to manufacture all-ceramic restorations by traditional milling. However, traditional milling presents challenges such as material waste, limited surface deta...

Aim Early childhood caries is the most common chronic infectious disease in children in the United States. This study, which is part of a larger, longitudinal study exploring oral microbiological components of caries development in children, reports on the impact of total mutans streptococci (MS), total acid tolerant bacteria and Candida species on...

The intersection between the human oral microbiome and oral health is an emerging area of study which has gained momentum over the last decade. This momentum has motivated a search for associations between the oral microbiome and oral cancer, in hopes of identifying possible biomarkers that facilitate earlier diagnosis and improved prognosis for pa...

Early childhood caries (ECC) is a common chronic infectious disease of childhood with a complex etiology and many contributing risk factors. Its prevalence is greater in certain racial and ethnic minority groups and populations with low socioeconomic status. Among the species of bacteria that contribute to the progression of dental caries, Streptoc...

Aim: The purpose of this study was to investigate the presence of Streptococcus mutans, Streptococcus sobrinus , and Lactobacillus species in an American Indian population displaying a high incidence of severe early childhood caries (S-ECC) and to explore the genotypic diversity and fidelity of transmission of S. sobrinus in this population. Method...

Purpose/aim To analyze potential factors associated with levels of selected oral pathogens, as well as total aerobic bacterial species, among nursing home residents. Materials and methods Nursing home residents were divided into three groups (G1 included people with teeth but no dentures, G2 included people with teeth and dentures, and G3 included...

1 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. 2 Materials and methods A convenience sample of 8 Ea...

Purpose: To assess the role of sociodemographic, dietary, and clinical factors in early mutans streptococci (MS) colonization in children aged 6 to 24 months who were followed for 18 months. Materials and methods: Ninety-four children (mean age: 11.5 ± 4.99 months at baseline) were enrolled in the study from the Women, Infants and Children Suppl...

Mutans streptococci (MS), specifically Streptococcus mutans (SM) and Streptococcus sobrinus (SS), are bacterial species frequently targeted for investigation due to their role in the etiology of dental caries. Differentiation of S. mutans and S. sobrinus is an essential part of exploring the role of these organisms in disease progression and the im...

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 i...

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

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 c...

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 per...

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 w...

Severe Early Childhood Caries (S-ECC) is a terribly aggressive and devastating disease that is all too common in lower socio-economic children, but none more so that what is encountered in American Indian Tribes. Nationwide, approximately 27% of 2-5 year olds have decay while 62% percent of American Indian/Alaska Native children in the same age gro...

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 t...

Objectives: American Indian (AI) children are at risk for chronic diseases associated with marginal early nutrition environments. We describe nutrient intakes and beverage patterns of AI women during the early postnatal period to identify nutritional adequacy and beverage habits. Methods: 24 hour recalls and beverage frequency questionnaires were a...

Objective: Dental caries is the most common chronic disease of childhood. While children of all races and socioeconomic statuses get caries, they are highly prevalent in children from low socioeconomic statuses, specifically American Indian and Alaskan Native (AI/AN) children. We are currently conducting a large scale examination of SM transmission...

Objective: Severe early childhood caries (SECC) is a debilitating form of tooth decay and is prevalent among lower socio-economic groups. Streptococcus mutans (SM) and Streptococcus sobrinus (SS) are major etiologic agents in SECC. SS is less common than SM but is more closely associated with high caries activity. Numerous SS and SM were isolated f...

Background: Severe early childhood caries is common in minority populations, particularly American Indian children. While Streptococcus mutans (SM) is still considered a primary etiological agent for this aggressive disease, Streptococcus sobrinus (SS) can also be present. Data from our current cohort study indicate a high percentage of SS present...

Objective: The aims of this study were to describe deciduous tooth eruption in an American Indian population, to compare patterns of eruption by gender and to contrast them with other populations. Method: A group of 239 mother-child dyads participated in a longitudinal oral health project conducted on the reservation of a Northern Plains trib...

Objectives: Streptococcus mutans (SM) is a primary microbiological agent of dental caries, a very prevalent chronic disease of childhood. Children from populations with lower socioeconomic status, particularly Hispanic, African-American, and American Indian, display a significantly higher incidence of caries. Our current study is focusing on transm...

Objective: Early childhood caries (ECC) is rampant among American Indian children, but there has been relatively little study of this problem. This paper reports on the prevalence of caries at the person, tooth and tooth surface level for a group of American Indian children at age 36 months. Method: Pregnant women from a Northern Plains Tribal co...

Background: Dental caries is one of the most common chronic diseases to affect children in the United States today. However, it is not evenly distributed among populations around the world. Streptococcus mutans (SM) is still widely regarded as the primary etiological agent of dental caries. Objective: To compare Streptococcus mutans genotypes in...

Objective: Previous studies have shown that American Indian and Alaskan Native (AI/AN) children have a high incidence of decay at a young age. Few studies have assessed causative factors. The purpose of this paper is to assess the relationship between antibiotic exposure and oral flora of very young children from a Northern Plains Tribal Community....

OBJECTIVES: This is a 36 month birth-cohort study examining rampant early childhood caries (ECC) among American Indian children from a Northern Plains Tribal community. Regular oral exams, plaque samples, and caregiver interview questionnaires serve as a rich analytical source for ECC investigation. This paper reports on the prevalence of caries, a...

Histatins are human salivary gland peptides with anti-microbial and anti-inflammatory activities. In this study, we hypothesized that histatin 5 binds to Porphyromonas gingivalis hemagglutinin B (HagB) and attenuates HagB-induced chemokine responses in human myeloid dendritic cells. Histatin 5 bound to immobilized HagB in a surface plasmon resonanc...

Streptococcus mutans is a principal etiologic agent in the development of dental caries due to its exceptional aciduric and acidogenic properties, and its ability to adhere and accumulate in large numbers on tooth surfaces in the presence of sucrose. Sucrose-dependent adherence is mediated by glucans, polymers of glucose synthesized from sucrose by...

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 thr...

Oral mucosal and salivary lipids exhibit potent antimicrobial activity for a variety of Gram-positive and Gram-negative bacteria; however, little is known about their spectrum of antimicrobial activity or mechanisms of action against oral bacteria. In this study, we examine the activity of two fatty acids and three sphingoid bases against Porphyrom...

The purpose was to compare whether mothers exposed to an autonomy-supportive psychoeducational videotaped message, informed by self-determination theory (SDT), demonstrated greater changes in behavior concerning their children's oral health than mothers exposed to a neutral message delivered by brochure. Data were collected at baseline, one- and si...

Objectives: The prevalence and severity of dental caries is very high among young American Indian children, yet little is known about caries risk factors in this population or why some of these children remain caries free. The purpose of this paper is to report preliminary assessment of risk factors for caries in a group of 22-month-old American In...

Objectives: To explore caries prevalence in a sample of very young, high-risk, low-income children, and to identify risk factors associated with early childhood caries (ECC) in this group. Methods: Data analyzed represent baseline information collected from 320 children aged 12 to 35 months enrolled in southeastern Iowa WIC programs. Children wer...

Oral mucosal lipids exhibit potent and variable antimicrobial activity in Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. We have shown, via two-dimensional difference in-gel electrophoresis (2D-DIGE), that treatment with the fatty acid, sapienic acid (SA), alters whole-cell bacterial protein profile...

Synopsis As one moves from the skin across the vermilion region of the lip and into the oral cavity, the oral mucosa is encountered. The oral mucosa consists of connective tissue known as the lamina propria covered by a stratified squamous epithelium. In the regions of the hard palate and gingiva, the epithelium is keratinized like the epidermis. I...

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, dihydrosp...

Objectives: This paper reports the prevalence and severity of caries in a group of 16-month-old American Indian children. Methods: The study is an ongoing longitudinal study of risk factors for caries in children from a Northern Plains Tribal community. Children were examined for caries and risk factor data collected at approximately 1, 4, 8, 12, a...

Objective: To describe the onset of dental caries in American Indian children 1-16 months of age. Method: Mothers from a Tribal community were recruited to participate in a longitudinal study of risk factors for caries in their children. Mother-child dyads were enrolled when the child was approximately 1 month (V1). Baseline data included plaque...

Objectives: The objective of this study is to assess relationships between the presence or absence of mutans streptococci (MS) and other covariates in children aged 12-49 months. Methods: Data were analyzed using baseline information from 411 children enrolled in the Special Supplemental Food Program for Women, Infants and Children (WIC) who partic...

Objective: Lollipops containing licorice root extract, Glycyrrhizol A, have been developed to reduce salivary levels of S. mutans, thus providing parents with another mode of caries prevention for their children. This pilot study sought to evaluate compliance and attitudes toward the “Lollipop Regimen.” Method: 35 Head Start children were instruc...

Long chain bases: sphingosine, phytosphingosine, and dihydrosphingosine, and fatty acids: lauric acid and sapienic acid, commonly found on oral mucosa and on skin have potent antimicrobial activity for a variety of Gram-positive and Gram-negative bacteria including Porphyromonas gingivalis. Treatment with these lipids also induces striking ultrastr...

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 l...

The purpose of this study was to determine the effect of the association of 1% chlorhexidine varnish (CHX) and 40% xylitol solution (XYL) on Streptococcus mutans (SM) counts and plaque indices in 2- to 5-year-olds. Sixty-eight children were selected with medium levels (1 x 10³) to very high levels (>1 x 10⁵) of SM in the saliva. Subjects were divid...

Skin Surface Lipids Oral Mucosal Surface Lipids Historical Perspectives on Antimicrobial Lipids Lauric Acid and Sapienic Acid Long-Chain Bases Conclusions References

Introduction Microflora of the Skin The Staphylococci and Streptococci: Prominent Opportunistic Pathogens Staphylococcus Epidermidis Staphylococcus Aureus Microflora of the Oral Mucosa Summary References

The purpose of this study was to determine the presence and relative composition of neutral lipids in human saliva. Whole unstimulated saliva was collected from 12 subjects ranging from 21 to 29 years old. Samples were lyophilized, and lipids were extracted using chloroform-methanol. Lipids were analysed by thin-layer chromatography. Human saliva c...

Antimicrobial peptides (AMPs) are among the repertoire of host innate immune defenses. In the oral cavity, several AMPs are present in saliva and have antimicrobial activities against oral bacteria, including Streptococcus mutans, a primary etiological agent of dental caries. In this study, we hypothesized that unique S. mutans strains, as determin...

OBJECTIVES: The purpose of this study was to determine the concentration of free sphingosine in human saliva. Previous work has demonstrated free sphingosine in the superficial layers of oral epithelia, at oral mucosal surfaces and in saliva. METHODS: Approximately 10 mL of unstimulated whole saliva was collected from 12 Caucasian subjects ranging...

Objectives: The goal of this pilot study was to assess the efficacy of herbal lollipops (Dr. John's Candies) containing licorice root extract, Glycyrrhizol A, in reducing salivary levels of mutans streptococci (MS). Methods: 165 subjects from the University of Iowa College of Dentistry were screened for salivary MS levels, and 49 had sufficient lev...

Objectives: Streptococcus mutans (SM) are considered the primary etiologic agent associated with dental caries. A study is currently being undertaken in a Native American tribe, known to exhibit rampant early childhood caries, to examine vertical transmission of SM strains to children and whether these strains, or possibly other oral bacteria, expr...

Objectives: Streptococcus mutans (SM) is a primary etiological agent of dental caries, the single most prevalent chronic disease of childhood. Lower Socioeconomic children, particularly Hispanic, African-American, and Native American, display a significantly higher incidence of caries. We are currently conducting an epidemiological study focusing o...

Lipids commonly found on the skin and in oral mucosa are increasingly being recognized as innate immune molecules with antimicrobial activity against gram positive and gram negative bacteria. In previous studies, we showed antimicrobial activity of phytosphingosine, sphingosine, dihydrosphingosine, and sapienic acid against several gram-positive an...

Objectives: Early childhood caries is a prevalent disease in the United States. In particular, 76 to 95% of 2-4 year old Native American children have a history of decay. We are currently conducting an epidemiological study focusing on transmission of S. mutans genotypes from mother to child in an American Indian population. We are reporting here o...

The study was conducted to determine the bactericidal activity of a stabilized chlorine dioxide oral rinse (ClōSYS Oral Rinse) compared to products currently available on the market. Oral bacteria associated with gingivitis and periodontitis were exposed to rinses for one minute and five minutes. The numbers of colony forming units per milliliter (...

The skin and tear film contain complex mixtures of lipids that act individually or synergistically with proteins and peptides to provide strong antimicrobial barriers at the cutaneous and ocular surfaces. These lipids have antimicrobial activity when isolated from these tissues and tested against Gram-positive bacteria, Gram-negative bacteria, and...

The purpose of this study was to determine bactericidal efficacy of 0.04% stabilized chlorine dioxide, 3% sodium hypochlorite, 2% chlorhexidine gluconate, and sterile distilled water in a polymicrobial biofilm model. Roots of 35 permanent bovine incisors had pulps extirpated, and their apical size and root length were standardized. Teeth were coate...

Objectives: The purpose of this study was to assess associations between genotypes at candidate loci and the presence of dental caries in 151 children aged 2-5 years. Subjects were recruited from a pediatric dental clinic serving low income families in an Iowa community with a significant Hispanic minority. Methods: Dental caries outcome, defined a...

Objectives: Caries is a prevalent chronic disease in the United States and is the second most common disease in children. In particular, 76% of 2-4 year old Native American Indians (AI) have a history of decay. Methods: We have analyzed 7 AI caries active (CA) subjects and 6 AI caries inactive (CI) subjects to enumerate bacterial species associated...

Objectives: Mothers vary in their knowledge of what constitutes effective oral health child care and in their behavioral intentions to enact ECC preventative care. This study investigated the associations of knowledge and behavioral intentions as well as ECC-related outcomes associated with such knowledge and intentions. Methods: Data were collecte...

Objectives: Dental caries in early childhood is a significant public health problem. The purpose of these investigations was to describe early childhood caries experience in a high risk population and assess the role of potential risk factors. Methods: Data were collected from mothers of 415 WIC-enrolled children aged 6 to 48 months who were partic...

Lipids are increasingly being recognized as having antimicrobial activity against gram positive and gram negative bacteria that colonize the skin and oral cavity. However, little is known about the spectrum of antimicrobial activity or mechanisms of action. Objectives: The objectives of this study were to determine potential minimal inhibitory conc...

Objectives: Streptococcus mutans (SM) is considered a primary microorganism in the etiology of dental caries and previous studies have shown considerable diversity in genotypes of SM. However, it is unknown to what extent SM genotypes vary in virulence potential. If differences in strain distribution and/or virulence potential can be linked to cari...

Objectives: CloSYSII is a novel antibacterial rinse that has a stabilized chlorine dioxide formulation. The purpose of this study was to compare the bactericidal activity of this rinse with other oral rinses against 17 species of bacteria. Methods: Seventeen bacterial species commonly associated with oral health or disease were chosen for these stu...

Dental caries has been associated with sugared beverage intakes and presence of plaque; however, the relationship between sugared beverage intakes and plaque is unclear. Objective: Our objective was to investigate relationships among sugared beverage intakes, plaque and dental caries in young children. Methods: Mothers (n=189) with children aged 2-...

OBJECTIVES: The purpose of this study was to determine the presence and relative composition of lipids in human saliva. Previous studies have suggested nonpolar lipids consisting of cholesterol (CH), fatty acids (FA), triglycerides (TG) and cholesterol esters (CE) are present. METHODS: Approximately 10 mL of unstimulated whole saliva was collected...

Genotypic analyses of Streptococcus mutans using fingerprinting methods depend on a few genetic loci being different but do not reveal the underlying genome-wide differences between strains. We used comparative genomic hybridization (CGH) with 70-mer oligonucleotide microarrays containing open reading frames (ORFs) from S. mutans strain UA159 to ex...

This study evaluated the ability of a resin-based system (Resilon/Epiphany) and gutta-percha/sealer with warm vertical or cold lateral compaction to prevent coronal leakage. A polymicrobial suspension in a dual-chamber model was used. Seventy extracted maxillary incisors were prepared, divided into 4 groups, and obturated: Group 1, lateral compacti...

Objectives: CloSYSII is a novel antibacterial rinse that has a stabilized chlorine dioxide formulation. The purpose of this study was to determine bactericidal activity of a 0.5% rinse against polymicrobial biofilms containing both gram-positive and negative bacteria. Methods: The following bacteria were used in this study: Actinomyces viscosus, St...

Objective: Enterococcus faecalis is commonly found in the oral microbiota and is often associated with endodontic failure. This study analyzed multiple E. faecalis isolates from saliva, crown, and endodontically-treated teeth to determine genotypes associated with endodontic failure and to determine the diversity and similarity of genotypes from di...

Objectives: This study compared whether mothers exposed to an autonomy-supportive psychoeducational videotaped message, facilitated by self-determination theory (SDT), demonstrated greater changes in knowledge, behavioral intent and subsequent behavior concerning their children's oral health than mothers exposed to a neutral message delivered by br...

Objectives: Streptococcus mutans (SM) is considered a primary etiological agent in the development of dental caries. Lower socioeconomic (SES) populations exhibit a discouraging disparity in the incidence and prevalence of caries. Our previous studies have shown diversity in SM genotypes among a cohort of subjects from lower SES families in Appalac...

Objective: This cross-sectional study explored socioeconomic, dietary, genetic and bacterial factors associated with caries in children age 2-5 years attending a dental clinic for low income families. Methods: The study recruited 195 pre-school children, of whom 190 were 2 to 5 years old, from a pediatric dental clinic for low-income families in...

Objectives: Timing and quantity of fluoride intake are key determinants of dental fluorosis, but human and animal investigations suggest a genetic component, including the possibility of gene-environment interaction. The aim of this study was to assess the possibility of such interaction, in this case, differential susceptibility to fluorosis at a...

Objectives: Streptococcus mutans (SM) is a major etiological agent in caries; however, growing evidence suggests that other organisms likely have a role in caries development. We previously showed that non-SM acidogenic (ASA) streptococci appeared to be associated with incipient lesions in young children. The purpose of our ongoing studies has been...

Objectives: Streptococcus mutans (SM) is considered a primary etiological agent in the development of dental caries. We and others have previously shown that there is considerable diversity in genotypes of SM. However, it is unknown to what extent SM genotypes vary in virulence potential. We examined biofilm formation and acidogenicity of unique SM...

Objectives: This pilot study assessed associations between genotypes at candidate loci and the presence of caries in the primary dentition. Methods: Two distinct samples from the same community with a significant Hispanic minority completed clinical dental exams and DNA collection using identical protocols. One sample included children enrolled i...

Objectives: Streptococcus mutans (SM) is considered a primary etiological agent in the development of dental caries. Lower socioeconomic (SES) populations exhibit a discouraging disparity in the incidence and prevalence of caries. Our previous studies have shown diversity in SM genotypes among a small cohort of subjects from lower SES families in A...

Background: Antimicrobial peptides are among the repertoire of host non-specific immune defenses. Several studies have tested the susceptibility of Streptococcus mutans to these peptides, though primarily laboratory strains have been examined. We hypothesize that the presence of these peptides in saliva, and accumulated within dental plaque, can sh...

The purpose of this study was to create a monoculture biofilm of a clinical isolate of Enterococcus faecalis and to determine susceptibility against four antimicrobial irrigants. Biofilms were subjected to 1-, 3-, and 5-minute exposures to one of the following irrigants: 6% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX) or one of two...

Early childhood caries (ECC) is a challenging public health problem in the United States and elsewhere; however, there is limited information concerning risk factors in very young children. The purpose of this study was to assess baseline risk factors for 18-month caries prevalence as part of a longitudinal study of high-risk children. About 212 ch...

Vital signs aid in assessing patient health and the disease severity. The objectives of this study were to determine changes in vital signs of patients with pulpal necrosis (PN) and acute apical abscess (AAA). The vital signs measured at the emergency visit were blood pressure, heart rate, temperature, and lymphadenopathy. Visual analogue scales (V...

Dental caries in early childhood is an important public health problem. Previous studies have examined risk factors, but they have focused on children during the later stages of the disease process. The purpose of this study was to assess the factors associated with caries in children aged 6 to 24 months as part of a cross-sectional analysis. Two h...

The skin surface represents our interface with the external environment, and as such, is our first line of defense against microbial colonization and infection. Lipids at the skin surface are thought to underlie at least part of an antimicrobial barrier. Some of these lipids are synthesized in the epidermis and are carried to the surface as cells d...

Summary form only given. The "plasma needle" device produces a small-diameter low-power atmospheric-pressure glow discharge. It is intended for dental or medical applications. Radio-frequency high voltage is applied to a single needle electrode located inside a concentric gas-flow nozzle. The nozzle has a diameter of a few millimeters, and the plas...

The use of chlorhexidine as a topically applied oral antiseptic is well documented; however, clinical studies examining the effects of chlorhexidine gel on in situ dental caries are limited. This study utilized an in situ caries model and a modified crossover design to examine whether the addition of a biweekly topical, alcohol-free, 1% chlorhexidi...

The purpose of this investigation was to compare the effectiveness of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of Resilon pellets. Resilon pellets were randomly selected, contaminated with Enterococcus faecalis, and disinfected with 5.25% sodium hypochlorite, MTAD, or 2% chlorhexidine. Positive and negative co...

Streptococcus mutans (S. mutans) bacteria were killed using a low-power millimeter-size atmospheric-pressure glow-discharge plasma or plasma needle. The plasma was applied to a culture of S. mutans that was plated onto the surface of an agar nutrient in a Petri dish. S. mutans is the most important microorganism for causing dental caries. A spatial...

The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then tr...

Growing evidence from clinical studies suggests that mothers using xylitol gums or lozenges have decreased levels of Streptococcus mutans (SM) and do not transmit these cariogenic bacteria as readily to their children. To begin to determine mechanisms for these clinical findings and to explore potential synergism of antimicrobial combinations, we s...

Summary form only given. A spatially-resolved diagnostic of atmospheric-pressure plasmas is demonstrated. This diagnostic makes use of an agar plate, i.e., a Petri dish filled with agar and plated with bacterial suspension. When a flowing atmospheric-pressure plasma impinges on the plate, bacteria are inactivated due to exposure to plasma-generated...

Endotoxin, elaborated by gram-negative organisms, is an important factor in apical periodontitis. The objective of this study was to evaluate the magnitude of endotoxin penetration through root canal treated teeth using a dual chamber model system. Forty-four maxillary anterior teeth were prepared endodontically and canals filled either by lateral...

The goal of this study is to determine if the smear layer affects the passage of bacteria through or around obturating material as evidenced by penetration of bacteria through and out the canal. Specifically, this study focused on determining the effect of the smear layer on the magnitude of bacterial penetration through the apical foramen. Thirty...

Porphyromonas endodontalis is a black-pigmented, obligate anaerobic rod-shaped bacterium implicated as playing a major role in endodontic infections. We have previously shown that P. endodontalis requires the porphyrin nucleus, preferably supplied as hemoglobin, as a growth supplement. The bacteria also actively transport free iron, although this a...

We investigated the frequency and patterns of biological-monitoring-test contamination and the effect of contamination on the growth of test organisms. Overall, the contamination rate was 0.81%, but the rate of contamination varied significantly by sterilization method. Contamination did not appear to inhibit growth of test organisms.

Standard minimal inhibitory and bactericidal concentration determinations provide a rapid screening method for assessing antimicrobial resistance. The information obtained may not be applicable to the in vivo situation where an infection is caused by microorganisms growing in biofilms. To more readily address this disparity in response to antimicro...

Porphyromonas endodontalis, like other Porphyromonas species, has a complex set of nutritional requirements. In addition to being an obligate anaerobe, the bacterium must be grown in a complex medium consisting of amino acids, reducing agents and heme compounds. P. endodontalis accumulates high concentrations of heme pigments to the extent that col...