Dentin tubule occlusion by a 38% silver diamine fluoride gel: an in vitro investigation.

OBJECTIVE: Silver diamine fluoride (SDF) is effective in treatment of dentin hypersensitivity and caries lesions. However, the non-viscous solution does not easily allow clinicians to control the application area. A 38% SDF experiment gel was compared in vitro to commercial SDF for its ability to penetrate and occlude dentinal tubules. MATERIALS AND METHODS: Human root surface dentin specimens were treated with gelled or standard 38% SDF or negative control. Penetration behavior was established by Drop Shape Analysis. Precipitates at the surface and within tubules were analyzed by SEM and EDX after treatment; Results: penetration depths up to 500 µm were observed for both SDF formulations. Both formulations occluded dentinal tubules similarly. Precipitates on the dentin surface and within dentinal tubules were found for both SDF formulations, with a slight tendency for the experimental gel SDF product to be more abundant than the commercially available one. DISCUSSION: behavior of the experimental 38% SDF gel formulation appeared indistinguishable from the commercial 38% SDF product with respect to dentinal tubule penetration and occlusion. CONCLUSIONS: The experimental 38% SDF gel may be a suitable intervention for the prevention of dentin hypersensitivity.

Fluorides and Other Preventive Strategies for Tooth Decay.

We focus on scalable public health interventions that prevent and delay the development of caries and enhance resistance to dental caries lesions. These interventions should occur throughout the life cycle, and need to be age appropriate. Mitigating disease transmission and enhancing resistance are achieved through use of various fluorides, sugar substitutes, mechanical barriers such as pit-and-fissure sealants, and antimicrobials. A key aspect is counseling and other behavioral interventions that are designed to promote use of disease transmission-inhibiting and tooth resistance-enhancing agents. Advocacy for public water fluoridation and sugar taxes is an appropriate dental public health activity.

Efficacy evaluation of an anti-caries varnish: protocol for a phase II randomised controlled trial.

INTRODUCTION: Dental caries (tooth decay) is a common disease in which the products of sugar metabolism by certain bacteria that populate the tooth surface induce the development and progression of lesions (cavities). This is a phase II single-centre randomised, double-blind, active-controlled, parallel-group trial to assess the efficacy of a combination povidone iodine and sodium fluoride dental varnish to determine if it is superior to a varnish containing only sodium fluoride in the prevention of new caries lesions. The objective of this report is to describe the rationale and protocol for the trial. METHODS AND ANALYSIS: The study site is Pohnpei State, Federated States of Micronesia. The study population is 284 children 48-84 months old. The primary outcome will be the surface-level primary molar caries increment (d2-3mfs/DMFS) at 2 years post baseline. The incremental dental caries at 1 year will also be compared between the two interventions. The secondary outcome is the Facial Image Scale after the initial treatment and after the fifth treatment at 1 year that gauges the child's response to the treatment. ETHICS AND DISSEMINATION: The Western Institutional Review Board (designated IRB) and the Institutional Review Board of the College of Micronesia-FSM approved all study procedures. The US Food and Drug Administration (FDA) has issued IND 128835 covering this study. The study results will be published and submitted to the FDA in support of a new drug application. TRIALREGISTRATION NUMBER: NCT03082196.

Clinical guidelines for management of dry eye associated with Sjögren disease.

PURPOSE: To provide a consensus clinical guideline for management of dry eye disease associated with Sjögren disease by evaluating published treatments and recommending management options. DESIGN: Consensus panel evaluation of reported treatments for dry eye disease. METHODS: Using the 2007 Report of the International Workshop on Dry Eye (DEWS) as a starting point, a panel of eye care providers and consultants evaluated peer-reviewed publications and developed recommendations for evaluation and management of dry eye disease associated with Sjögren disease. Publications were graded according to the American Academy of Ophthalmology Preferred Practice Pattern guidelines for level of evidence. Strength of recommendation was according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines. RESULTS: The recommendations of the panel are briefly summarized herein. Evaluation should include symptoms of both discomfort and visual disturbance as well as determination of the relative contribution of aqueous production deficiency and evaporative loss of tear volume. Objective parameters of tear film stability, tear osmolarity, degree of lid margin disease, and ocular surface damage should be used to stage severity of dry eye disease to assist in selecting appropriate treatment options. Patient education with regard to the nature of the problem, aggravating factors, and goals of treatment is critical to successful management. Tear supplementation and stabilization, control of inflammation of the lacrimal glands and ocular surface, and possible stimulation of tear production are treatment options that are used according to the character and severity of dry eye disease. SUMMARY: Management guidelines for dry eye associated with Sjögren's disease are presented.

An examination of the advances in science and technology of prevention of tooth decay in young children since the Surgeon General's Report on Oral Health.

This paper addresses a number of areas related to how effectively science and technology have met Healthy People 2010 goals for tooth decay prevention. In every area mentioned, it appears that science and technology are falling short of these goals. Earlier assessments identified water fluoridation as one of the greatest public health accomplishments of the last century. Yet, failure to complete needed clinical and translational research has shortchanged the caries prevention agenda at a critical juncture. Science has firmly established the transmissible nature of tooth decay. However, there is evidence that tooth decay in young children is increasing, although progress has been made in other age groups. Studies of risk assessment have not been translated into improved practice. Antiseptics, chlorhexidine varnish, and polyvinylpyrrolidone iodine (PVI-I) may have value, but definitive trials are needed. Fluorides remain the most effective agents, but are not widely disseminated to the most needy. Fluoride varnish provides a relatively effective topical preventive for very young children, yet definitive trials have not been conducted. Silver diamine fluoride also has potential but requires study in the United States. Data support effectiveness and safety of xylitol, but adoption is not widespread. Dental sealants remain a mainstay of public policy, yet after decades of research, widespread use has not occurred. We conclude that research has established the public health burden of tooth decay, but insufficient research addresses the problems identified in the report Oral Health in America: A Report of the Surgeon General. Transfer of technology from studies to implementation is needed to prevent tooth decay among children. This should involve translational research and implementation of scientific and technological advances into practice.

Amylase-binding protein B of Streptococcus gordonii is an extracellular dipeptidyl-peptidase.

The oral commensal bacterium Streptococcus gordonii interacts with salivary amylase via two amylase-binding proteins, AbpA and AbpB. Based on sequence analysis, the 20-kDa AbpA protein is unique to S. gordonii, whereas the 82-kDa AbpB protein appears to share sequence homology with other bacterial dipeptidases. The aim of this study was to verify the peptidase activity of AbpB and further explore its potential functions. The abpB gene was cloned, and histidine-tagged AbpB (His-AbpB) was expressed in Escherichia coli and purified. Its amylase-binding activity was verified in an amylase ligand binding assay, and its cross-reactivity was verified with an anti-AbpB antibody. Both recombinant His-AbpB and partially purified native AbpB displayed dipeptidase activity and degraded human type VI collagen and fibrinogen, but not salivary amylase. Salivary amylase precipitates not only AbpA and AbpB but also glucosyltransferase G (Gtf-G) from S. gordonii supernatants. Since Streptococcus mutans also releases Gtf enzymes that could also be involved in multispecies plaque interactions, the effect of S. gordonii AbpB on S. mutans Gtf-B activity was also tested. Salivary amylase and/or His-AbpB caused a 1.4- to 2-fold increase of S. mutans Gtf-B sucrase activity and a 3- to 6-fold increase in transferase activity. An enzyme-linked immunosorbent assay verified the interaction of His-AbpB and amylase with Gtf-B. In summary, AbpB demonstrates proteolytic activity and interacts with and modulates Gtf activity. These activities may help explain the crucial role AbpB appears to play in S. gordonii oral colonization.

Interaction of salivary alpha-amylase and amylase-binding-protein A (AbpA) of Streptococcus gordonii with glucosyltransferase of S. gordonii and Streptococcus mutans.

BACKGROUND: Glucosyltransferases (Gtfs), enzymes that produce extracellular glucans from dietary sucrose, contribute to dental plaque formation by Streptococcus gordonii and Streptococcus mutans. The alpha-amylase-binding protein A (AbpA) of S. gordonii, an early colonizing bacterium in dental plaque, interacts with salivary amylase and may influence dental plaque formation by this organism. We examined the interaction of amylase and recombinant AbpA (rAbpA), together with Gtfs of S. gordonii and S. mutans. RESULTS: The addition of salivary alpha-amylase to culture supernatants of S. gordonii precipitated a protein complex containing amylase, AbpA, amylase-binding protein B (AbpB), and the glucosyltransferase produced by S. gordonii (Gtf-G). rAbpA was expressed from an inducible plasmid, purified from Escherichia coli and characterized. Purified rAbpA, along with purified amylase, interacted with and precipitated Gtfs from culture supernatants of both S. gordonii and S. mutans. The presence of amylase and/or rAbpA increased both the sucrase and transferase component activities of S. mutans Gtf-B. Enzyme-linked immunosorbent assay (ELISA) using anti-Gtf-B antibody verified the interaction of rAbpA and amylase with Gtf-B. A S. gordonii abpA-deficient mutant showed greater biofilm growth under static conditions than wild-type in the presence of sucrose. Interestingly, biofilm formation by every strain was inhibited in the presence of saliva. CONCLUSION: The results suggest that an extracellular protein network of AbpA-amylase-Gtf may influence the ecology of oral biofilms, likely during initial phases of colonization.

Public health implications of smokeless tobacco use as a harm reduction strategy.

Harm reduction strategies involve promoting a product that has adverse health consequences as a substitute for one that has more severe adverse health consequences. Smokeless tobacco low in nitrosamine content offers potential benefits in reducing smoking prevalence rates. Possible harm arises from the potential for such products to serve as a gateway to more harmful tobacco products, public misinterpretation of "less harmful" as "safe," distraction from the public health goal of tobacco elimination, and ethical issues involved in advising those marketing these harmful products. We offer a research agenda to provide a stronger basis for evaluating the risks and benefits of smokeless tobacco as a means of reducing the adverse health effects of tobacco.

Verification of caries inhibition by a tartar control toothpaste.

OBJECTIVE: The anticaries properties of a silica-based, sodium fluoride (NaF) toothpaste containing tetrapotassium pyrophosphate (PPi) with anti-tartar properties (Aquafresh All Tartar Control) were assessed in specific pathogen-free Osborne-Mendel rats. METHODOLOGY: The dentifrice was compared to a silica-based, fluoride-free control toothpaste that contained PPi but no NaF, termed a "Placebo" (negative control), and a NaF-containing silica-based USP reference standard toothpaste which was used as a positive fluoride control toothpaste. Sixty weanling rats were randomly distributed into groups of 20; all were inoculated with S. mutans 10449S, ate cariogenic diet 2000, and drank demineralized water, ad libitum. Each toothpaste, contained in coded tubes, was applied to the dentitions of rats' teeth for one minute, twice daily on weekdays and once daily on weekends and holidays. There was no difference in weight gains or in recoveries of the S. mutans inoculant from tooth swabs among the groups at either the 24- or 38-day post-inoculation recovery date. After euthanasia at 42 days and defleshing, heads were randomly coded and scored blindly for carious lesions according to Keyes/Larson methods. Only after scoring was completed were the random codes broken to enable statistical analyses. Only after statistical analyses were completed and the data reported to sponsor were the identities of the test items revealed. RESULTS: Both the NaF/PPi-containing and the NaF-containing USP standard toothpaste groups had lower total enamel caries scores (29.8 to 30.6%, respectively) than the group treated with the fluoride-free PPi-containing control. Similar-dimensioned differences were evident both at smooth surface and sulcal enamel sites and in dentinal sites. All were statistically significant at p < 0.001. There were no statistically significant differences at any tooth surface category site between the two fluoride-containing toothpastes' effects. CONCLUSION: It is thus apparent that Aquafresh All Tartar Control, an anti-tartar NaF toothpaste, retains the anticaries benefit of a USP reference standard NaF toothpaste in vivo.

Identification and analysis of the amylase-binding protein B (AbpB) and gene (abpB) from Streptococcus gordonii.

The binding of salivary amylase to Streptococcus gordonii has previously been shown to involve a 20-kDa amylase-binding protein (AbpA). S. gordonii also releases an 82-kDa protein into the supernatant that binds amylase. To study this 82-kDa component, proteins were precipitated from bacterial culture supernatants by the addition of acetone or purified amylase. Precipitated proteins were separated by SDS-PAGE and transferred to a sequencing membrane. The P2 kDa band was then sequenced, yielding a 25 N-terminal amino acid sequence, CGFIFGRQLTADGSTMFGPTEDYP. Primers derived from this sequence were used in an inverse PCR strategy to clone the full-length gene from S. gordonii chromosomal DNA. An open reading frame of 1959 bp was noted that encoded a 652 amino acid protein having a predicted molecular mass of 80 kDa. The first 24 amino acid residues were consistent with a hydrophobic signal peptide, followed by a 25 amino acid N-terminal sequence that shared identity (24 of 25 residues) with the amino acid sequence of purified AbpB. The abpB gene from strains of S. gordonii was interrupted by allelic exchange with a 420-bp fragment of the abpB gene linked to an erythromycin cassette. The 82-kDa protein was not detected in supernatants from these mutants. These abpB mutants retained the ability to bind soluble amylase. Thus, AbpA, but not AbpB, appears sufficient to be the major receptor for amylase binding to the streptococcal surface. The role of AbpB in bacterial colonization remains to be elucidated.