Initiation Of Caries Research Articles

Dental caries vaccine

Dental caries is one of the most common diseases in humans. In modern times, it has reached epidemic proportions. Dental caries is an infectious microbiologic disease of the teeth that results in localized dissolution and destruction of the calcified tissue. Dental caries is a mulitifactorial disease, which is caused by host, agent, and environmental factors. The time factor is important for the development and progression of dental caries. A wide group of microorganisms are identified from carious lesions of which S. mutans , Lactobacillus acidophilus , and Actinomyces viscosus are the main pathogenic species involved in the initiation and development of dental caries. In India, surveys done on school children showed caries prevalence of approximately 58%. Surveys among the U.S. population showed an incidence of 45.3% in children and 93.8% in adults with either past or present coronal caries. Huge amounts of money and time are spent in treating dental caries. Hence, the prevention and control of dental caries is the main aim of public health, eventually the ultimate objective of public health is the elimination of the disease itself. Recently, dental caries vaccines have been developed for the prevention of dental caries. These dental caries vaccines are still in the early stages.

Early Childhood Caries (ECC): An infectious transmissible oral disease

Dental caries in babies and toddlers is called Early Childhood Caries (ECC). It is an infectious and transmissible die-to-bacterial disease. Detailed knowledge regarding the acquisition and transmission of infectious agents facilitates a more comprehensive approach toward prevention. Mutans streptococci are important organisms in the initiation and progression of dental caries. Recent evidence demonstrates that these bacteria are found in the mouths of pre-dentate infants and are acquired via vertical and/or horizontal transmission from human reservoirs. This information should facilitate the focusing of clinical interventions that prevent or delay infant infection, thereby reducing the prevalence of dental caries (ECC) in babies and toddlers.

Additive attenuation of virulence and cariogenic potential of Streptococcus mutans by simultaneous inactivation of the ComCDE quorum-sensing system and HK/RR11 two-component regulatory system

The genome of Streptococcus mutans harbours 13 two-component signal transduction systems (TCSTSs). Of these, a peptide-mediated quorum-sensing system, ComCDE, and the HK/RR11 two-component system are well known to regulate several virulence-associated traits in in vitro experiments, including genetic competence, bacteriocin production, biofilm formation and stress responses. In this study, we investigated the hypothesis that inactivation of ComCDE, HK/RR11 or both systems would attenuate the virulence and cariogenicity of S. mutans. The results showed that simultaneous inactivation of both signal transduction systems additively attenuated S. mutans virulence and cariogenicity, since inactivation of either of these systems alone did not result in the same degree of effect. The double deletion mutant SMcde-hk11 was defective in genetic competence, had a reduced acid production, was unable to grow at pH 5.0 and formed an abnormal biofilm with reduced biomass. Animal studies showed that this mutant had reduced capabilities for oral colonization, succession and initiation of dental caries. A competitive index (CI) analysis using a mixed-infection animal model revealed that all the mutants, particularly SMcde-hk11, had reduced fitness in their ecological niches and were unable to compete with the wild-type strain for persistence in dental biofilms. The evidence from this study suggests that the ComCDE and HK/RR11 signal transduction systems can be considered to be novel targets for the development of strategies in the prevention and treatment of S. mutans infections.

Case definition, Aetiology and Risk assessment of Early Childhood Caries (ECC): A revisited review

To provide a review of the existing literature on early childhood caries (ECC) with particular reference on the nomenclature, case definition, epidemiology, etiology and risk assessment. An electronic search was used to identify and critically review papers that have been published and are pertinent to the above issues, evaluate and compile the reported evidence. The term ECC has been adopted to more accurately describe dental caries that affects primary dentitions, replacing previously used terminology that associated the disease with the nursing habit. Suggested ECC case definition uses caries patterns as defining criteria, however, further refinement to include different clinical expressions of a varying severity is necessary. Significant percentages of preschool child populations are affected by ECC today, with the disease concentrating disproportionately in deprived families. Early colonization by mutans streptococci (MS) is associated with increased ECC development, with bacteria being transmitted in both vertical and horizontal ways. Dietary factors related to sugar consumption predispose to early MS colonization and establishment and increase the risk for ECC development, being part of the causal chain. Inappropriate bottle and breast-feeding behaviors also increase the risk, without showing a direct causal relationship. High risk children belong to ethnic minority groups and to low income families with poor parental behaviors and attitudes. Further high-quality studies are needed to explore the role bacteria other than MS may play in caries initiation and progression, elucidate the interaction of the saliva immune defence system with a potentially defective tooth, and investigate the effect distant behavioral factors have on the causal chain that leads to ECC development.

Evidence-Based Clinical Recommendations for the Use of Pit-and-Fissure Sealants: A Report of the American Dental Association Council on Scientific Affairs

This article presents evidence-based clinical recommendations for use of pit-and-fissure sealants developed by an expert panel convened by the American Dental Association Council on Scientific Affairs. The panel addressed the following clinical questions: Under what circumstances should sealants be placed to prevent caries? Does placing sealants over early (noncavitated) lesions prevent progression of the lesion? Are there conditions that favor the placement of resin-based versus. glass ionomer cement sealants in terms of retention or caries prevention? Are there any techniques that could improve sealants' retention and effectiveness in caries prevention? Staff of the ADA Division of Science conducted a MEDLINE search to identify systematic reviews and clinical studies published after the identified systematic reviews. At the panel's request, the ADA Division of Science staff conducted additional searches for clinical studies related to specific topics. The Centers for Disease Control and Prevention also provided unpublished systematic reviews that since have been accepted for publication. The expert panel developed clinical recommendations for each clinical question. The panel concluded that sealants are effective in caries prevention and that sealants can prevent the progression of early noncavitated carious lesions. These recommendations are presented as a resource to be considered in the clinical decision-making process. As part of the evidence-based approach to care, these clinical recommendations should be integrated with the practitioner's professional judgment and the patient's needs and preferences. The evidence indicates that sealants can be used effectively to prevent the initiation and progression of dental caries.

Three dimensional observation of the occlusal grooves in the maxillary first and second deciduous molars with micro-CT

The purpose of this study was clarify the morphological condition of occlusal grooves in the maxillary first and second deciduous molars with micro-CT. We took photographs of the maxillary deciduous molars using a micro-CT device and reconstructed the three-dimensional image of the anatomical crown using a three-dimensional visualization and measurement software. For observation and measurement of the occlusal grooves, twodimensional sliced images were generated 10 images at each groove. On the generated two-dimensional sliced images, we measured the occlusal angle, the depth of the occlusal groove and the enamel thickness at its bottom. The sites which showed smallest angle were distal portions of the central groove in maxillary first deciduous molar, and lingual groove in maxillary second deciduous molar. The occlusal groove in maxillary second deciduous molar was deeper than that of maxillary first deciduous molar in all sites examined, except for distal portion of the central groove. The enamel thickness in maxillary second deciduous molars tended to have thicker enamel than that of first deciduous molars. In maxillary first deciduous molars, most of the occlusal grooves exhibited the shape classified into type P. Whereas in maxillary second deciduous molars, the ratio of type P was relatively low, especially, lingual grooves consisted of type V, whose angle was less than 90 degree, type U and type I, which had the shape looked like a stick. Distal portion of the central groove of maxillary first deciduous molar, and lingual groove of maxillary second deciduous molar tend to be the initiation and predilection sites of dental caries due to the anatomical features of their occlusal fissures. Moreover, it is preferable to apply pit and fissure sealant into the occlusal fissures containing this region at an early point of the treatment.

Comparative Evaluation of the Marginal Sealing Ability of Fuji VII® and Concise® as Pit and Fissure Sealants

The anatomical pits and fissures of the teeth have long been recognized as susceptible areas for the initiation of dental caries. The extreme vulnerability to decay of these pits and fissures on the occlusal surfaces has prompted dental scientists to seek methods of caries prevention. Motivated by the role of pit and fissure sealants in caries prevention, the aim of this study was to compare the efficacy of Fuji VII glass ionomer sealant and Concise resin-based sealant. An in vitro study was undertaken using forty premolars extracted for orthodontic reasons. The teeth were divided into two groups and sealants were applied. One was an experimental group using Fuji VII as a pit and fissure sealant and the other a control group using Concise. The teeth were kept in gentian violet dye for 24 hours, the sectioned samples were observed for the extent of dye penetration, and scores were based on established scoring criteria. The comparison of the performance of the two groups showed a statistically significant difference. The Concise resin-based sealant performed better in terms of sealing ability than did the Fuji VII glass ionomer sealant.

Effect of Barley Coffee on the Adhesive Properties of Oral Streptococci

Some beverages and foods protect tooth surfaces against Streptococcus mutans colonization. Adhesion of S. mutans is a crucial step in the initiation and development of dental caries. In this study, we showed that barley coffee (BC), a beverage made from roasted barley, interferes with S. mutans adsorption to hydroxyapatite (HA), and we identified its antiadhesive components. The effects of sublethal concentrations (sub-MICs) of BC on the adhesion of S. mutans to saliva-coated HA beads were assessed using three experimental approaches: (A) Beads were pretreated with BC before adding bacteria, (B) BC and bacteria were added to the beads simultaneously, and (C) streptococci grown in the presence of sub-MICs of BC were added to the beads. All treatments induced variable but significant inhibition of S. mutans sucrose-dependent and -independent adherence to HA. Similar results were obtained with other oral streptococci. BC components were fractioned by dialysis and gel filtration chromatography; the <1000 Da molecular mass (MM) fraction, which contains polyphenols, zinc, and fluoride ions, and the >1000 kDa MM fraction, which consists of a potent brown antioxidant, melanoidin, both displayed antiadhesive properties. High-MM melanoidin was not detected in unroasted barley, indicating that it forms during the roasting process. Results suggest that BC consumption may influence the colonization of tooth surfaces by cariogenic bacteria.

Virulence properties of cariogenic bacteria

The importance of Streptococcus mutans in the etiology of dental caries has been well documented. However, there is growing recognition that the cariogenic potential of dental plaque may be determined by the composite interactions of the total plaque bacteria rather than solely the virulence properties of a single organism. This study will examine how the interactions of S. mutans with other biofilm constituents may influence the cariogenicity of plaque samples.In order to begin to investigate the effects of nonmutans streptococci on the cariogenic potential of S. mutans, we have examined the effects of Streptococcus gordonii on the virulence properties of the former organisms. These studies have indicated that S.gordonii can attenuate several potential virulence properties of S. mutans including bacteriocin production, genetic transformation, and biofilm formation. Therefore, modulation of the interactions between plaque bacteria might be a novel approach for attenuating dental caries initiation.

The complex oral microflora of high‐risk individuals and groups and its role in the caries process

The involvement of the oral biofilm in the caries process requires re-evaluation. The essential role of mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) in the caries process is not proven. Acid production by dental plaque is not dependent upon the presence of mutans streptococci; caries occurs in the absence of these species and their presence does not necessarily indicate caries activity. Other oral bacteria, non-mutans streptococci, Actinomyces spp. and Bifidobacterium spp., are acidogenic and aciduric. They outnumber mutans streptococci in dental plaque, and there are data which support a role for these bacteria in the initiation and progression of caries. Molecular studies demonstrate the great diversity and complexity of the flora associated with caries. Many taxa identified have not been cultured and the role of these taxa is not known. We have, in mutans streptococci, good markers of disease but not necessarily the aetiological agents of the disease. Considerably more research is required to investigate the transition of tooth surfaces from being intact and sound to the white spot lesion stage. A combination of conventional and molecular approaches are required to elucidate the involvement of an individual taxon and of microbial populations with particular traits in the caries process.

Fluorescent Detection of Oral Pathogens by a Solid-Phase Immunoassay on PDMS.

We have developed an array of sensors for the oral pathogen Streptococcus mutans (S. mutans) using an enzymelinked linked immunosorbent assay (ELISA) on a polydimethylsiloxane (PDMS) device. The model bacterial analyte, S. mutans, has been implicated in the initiation and progression of dental caries. The PDMS was modified with 3-aminopropyltriethoxysilance (APTS) and glutaraldehyde to covalently crosslink monoclonal anti-S. mutans immunoglobulin G (IgG) to the sensor surface. Successful IgG immobilization was verified by AFM and fluorescence imaging. Colloidal bacteria were captured on the sensor surface and labeled with immuno-active quantum dots (QDs), whose fluorescence was excited by an LED and detected by a CCD. The system was capable of detecting S. mutans concentrations as low as 6 106cells/ml in a 20 μl sample. This work represents a stable foundation for the development of a chair side diagnostic system capable of specific and sensitive detection of pathogens directly from oral fluid.

Streptococcus mutans Genotypes Isolated from Root and Coronal Caries

The aim of the present study was to evaluate the colonization profile and clonal distribution of Streptococcus mutans isolated from oral cavities that presented coronal and root caries lesions. The isolation and biochemical identification of mutans streptococci were carried out by using saliva samples, dental plaque, and tissue from the caries lesions. In order to confirm their molecular identity, S. mutans and Streptococcus sobrinus were submitted to the PCR method, using specific primers for portions of the glucosyltransferase genes (gtfB and gtfI, respectively). The AP-PCR method was used to detect the genetic polymorphism of S. mutans strains. Among the isolated and identified species, S. mutans showed a significantly greater frequency of isolation (59.2%) than the other mutans streptococci. Each of the subjects harbored two to ten genotypes of S. mutans, randomly distributed in different sites. S. mutans genotypes showed no evidence of variability in colonizing noncarious and carious surfaces within the same individual, nor evidence of etiologic differences between coronal and root caries. This study showed that no particular genotype of S. mutans is uniquely associated with the initiation and progression of caries, and that root and coronal caries can emerge in the presence of a broad spectrum of S. mutans clones.

The challenges of validating diagnostic methods relative to a conventional two-year caries clinical trial.

This paper is directed to the question, "What are the appropriate validation criteria for the use of a new clinical trial methodology as a replacement for a conventional two- to three-year caries study?" It is important to recognize that the objective of a two- to three-year randomized, controlled caries trial is to test a precisely framed hypothesis, regarding an experimental product's efficacy relative to a control product. The external validity of conventional two- to three-year caries clinical studies in determining the efficacy and safety of anti-caries products is well-accepted. However, caries clinical trials are not without limitations and have increasingly been viewed as inefficient with respect to measuring the disease process in a holistic manner. The endpoint of a caries lesion with loss of enamel integrity (cavitation) focuses on one end of the caries progression continuum at the expense of early caries initiation and progression. Several early caries detection methods have been developed that correlate with mineral loss of the tooth surface. These diagnostics differ from conventional visual-tactile and radiographic methods in that they are capable of detecting early non-cavitated lesions, and this can generate continuous data. As diagnostic methods become accepted, they will lead to study designs that diverge from the conventional two- to three-year caries studies. Modification of the existing two- to three-year conventional caries design for assessment of product effectiveness, whether by the introduction of a new diagnostic method or by modification of the overall clinical design, must result in a clinical design that is able to differentiate known treatments on the basis of caries prevention efficacy. Given that the fluoride dose response has been characterized in the literature, this should form the basis of any validation package for new methodologies. In conclusion, a minimum expectation for acceptance as a replacement to conventional testing should be that the method or design can differentiate products of known efficacy from one another and that the efficacy relationship observed in a two- to three-year conventional study can be observed with the new method or design.

Stress-responsive proteins are upregulated in Streptococcus mutans during acid tolerance.

Streptococcus mutans is an important pathogen in the initiation of dental caries as the bacterium remains metabolically active when the environment becomes acidic. The mechanisms underlying this ability to survive and proliferate at low pH remain an area of intense investigation. Differential two-dimensional electrophoretic proteome analysis of S. mutans grown at steady state in continuous culture at pH 7.0 or pH 5.0 enabled the resolution of 199 cellular and extracellular protein spots with altered levels of expression. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry identified 167 of these protein spots. Sixty-one were associated with stress-responsive pathways involved in DNA replication, transcription, translation, protein folding and proteolysis. The 61 protein spots represented isoforms or cleavage products of 30 different proteins, of which 25 were either upregulated or uniquely expressed during acid-tolerant growth at pH 5.0. Among the unique and upregulated proteins were five that have not been previously identified as being associated with acid tolerance in S. mutans and/or which have not been studied in any detail in oral streptococci. These were the single-stranded DNA-binding protein, Ssb, the transcription elongation factor, GreA, the RNA exonuclease, polyribonucleotide nucleotidyltransferase (PnpA), and two proteinases, the ATP-binding subunit, ClpL, of the Clp family of proteinases and a proteinase encoded by the pep gene family with properties similar to the dipeptidase, PepD, of Lactobacillus helveticus. The identification of these and other differentially expressed proteins associated with an acid-tolerant-growth phenotype provides new information on targets for mutagenic studies that will allow the future assessment of their physiological significance in the survival and proliferation of S. mutans in low pH environments.

Effect of carbohydrate fatty acid esters on Streptococcus sobrinus and glucosyltransferase activity

Mutans streptococci are oral bacteria with a key role in the initiation of dental caries, because their glucosyltransferases synthesize polysaccharides from sucrose that allow them to colonize the tooth surface. Among the strategies to prevent dental caries that are being investigated are (1) the inhibition of bacterial growth of mutans streptococci or (2) the inhibition of glucosyltransferases involved in polysaccharide formation. Pure fatty acid esters of sucrose, maltose and maltotriose were synthesized by an enzyme-catalyzed process and tested as inhibitors of two glucosyltransferases of great homology, those from Streptococcus sobrinus and Leuconostoc mesenteroides NRRL B-512F. In spite of having their nonreducing end glucose blocked at 6-OH, they did not inhibit dextran synthesis. However, their effect on the growth of S. sobrinus in the solid and liquid phase was notable. 6- O-Lauroylsucrose, 6 ′- O-lauroylmaltose and 6″- O-lauroylmaltotriose at 100 μg/mL showed complete inhibition of S. sobrinus in agar plates. Consequently, these nontoxic derivatives are very promising for inclusion in oral-hygiene products aimed at disrupting plaque formation and preventing caries.

Carious pulpitis: microbiological and histopathological considerations.

Dental caries is the result of microbial activities that induce the progressive localised destruction of teeth. Without treatment, this eventually results in infection of the dental pulp and surrounding periapical tissues. Although the bacteria responsible for caries initiation and early caries progression have been extensively studied, the microbiology of dentine caries reportedly shows considerable diversity and the associated microflora has not yet been fully identified. A search of the literature shows that few studies have analysed the microbiology of deep caries or examined the relationship between this microflora and the histopathology of chronic pulpitis in symptomatic teeth. The majority of the studies investigating the microbiology of carious dentine have used traditional culture methodology that has been reported to be fraught with difficulties and to underestimate the microbial populations. However, recent work using new technology in the form of Polymerase Chain Reaction (PCR) has shown potential by enhancing the identification and quantification of bacteria from complex environments. Application of this technology to carious dentine has identified an environment dominated by anaerobic organisms and containing significant numbers of Gram-negative bacteria that have been strongly implicated in endodontic infections subsequent to carious pulpitis. Examination of the histopathology of pulp sections from teeth extracted as a result of carious pulpitis showed pulpal reactions ranging from minimal inflammation to marked inflammatory infiltration of the pulp tissue. Of interest, were hard and soft tissue pathologic changes noted in the pulp tissues resulting from the combined effects of the carious microorganisms and the host tissue response. Improved knowledge of the microbial species associated with pulpitis could create the potential for development of diagnostic tools and restorative materials with appropriate antimicrobial properties.

A novel spectrofluorometric microassay for Streptococcus mutans adherence to hydroxylapatite

Adherence to the tooth surface by Streptococcus mutans is an important step in initiation of dental caries. Current in vitro methods used to study bacterial adherence are time-consuming and may involve the use of radiolabels. The aim of this study was to develop a more convenient, high-throughput, microtitre-plate assay of bacterial adherence to hydroxylapatite. S. mutans was labelled with the fluorescent indicator BCECF/AM and fluorescence measured using a spectrofluorometer. Fluorescence microscopy confirmed label uptake. Optimal labelling occurred at 120 min with 50 μM BCECF/AM in DMSO. Viability was similar in control untreated bacterial cells, bacteria treated with DMSO alone or with the label for up to 4 h. Preliminary adherence experiments were performed using four commercially available types of hydroxylapatite. Fluorescence from pre-labelled bacteria was measured for bound cells. The assay was then optimised with respect to time and bacterial concentration using Fluka crude hydroxylapatite. Time course studies demonstrated that adherence reached saturation by 30 min incubation when using 1×10 7 cfu/ml labelled bacteria to 1 mg hydroxylapatite, coated with PBS or saliva. The fluorescence-based adherence assay was highly reproducible in repeated analyses and was useful in demonstrating interference with adherence. In conclusion, this microtitre-plate assay offers a more convenient approach to examine streptococcal adherence and could be used to screen for potential anti-adhesive agents.

Effect of a Varnish Containing Chlorhexidine and Thymol (Cervitec®) on Approximal Caries in 13- to 16-Year-Old Schoolchildren in a Low Caries Area

Background: Previous studies on the effect of the chlorhexidine and thymol-containing varnish (Cervitec^®) have consistently shown a reduction in Streptococcus mutans, while the data on the caries-inhibiting effect are conflicting. Aim: To measure the effect of a chlorhexidine- and thymol-containing varnish (Cervitec) on approximal caries in a low caries population. Material: Eighty-five schoolchildren, 13 years of age, entered the study after being selected on the basis of bitewing radiographs. Children with at least one approximal lesion were included after informed consent. Methods: The study was carried out as a double-blind, randomized controlled trial according to a split-mouth design using Cervitec on one side and a placebo varnish on the other side. All approximal surfaces between molars and premolars were treated every 3rd month. After 2 years new bitewing radiographs were taken. A total of 73 children completed the 2-year study. Results: Neither the difference in number of new lesions between the Cervitec-treated and the placebo-treated side (d: –0.21; 95% CI: –0.57; 0.16) nor the mean difference in number of already existing lesions that progressed (d: –0.01; 95% CI: –0.33; 0.30) were statistically significant (pairedt test; p > 0.05). Conclusion: The results of our study do not indicate an effect of Cervitec on initiation or progression of approximal caries in a population with a low DMFS.

Crystal Structure of the V-region of Streptococcus mutans Antigen I/II at 2.4 Å Resolution Suggests a Sugar Preformed Binding Site

Antigens I/II are large multifunctional adhesins from oral viridans streptococci that exert immunomodulatory effects on human cells and play important roles in inflammatory disorders. Among them, Streptococcus mutans plays a major role in the initiation of dental caries. The structure of the V-region (SrV+, residues 464–840) of the antigen I/II of S. mutans has been determined using the multiwavelength anomalous diffraction phasing technique with seleno-methionine-substituted recombinant protein and subsequently refined at 2.4 Å resolution. The crystal structure of SrV+ revealed a lectin-like fold that displays a putative preformed carbohydrate-binding site stabilized by a metal ion. Inhibition of this binding site may confer to humans a protection against dental caries and dissemination of the bacteria to extra-oral sites involved in life-threatening inflammatory diseases. This crystal structure constitutes a first step in understanding the structure–function relationship of antigens I/II and may help in delineating new preventive or therapeutic strategies against colonization of the host by oral streptococci.

Artificial formed caries-like lesions around esthetic restorative materials

Dental restorations fail for a variety of reasons. Secondary caries is one of the primary causes of failure of dental restorations. One method for reducing frequency and severity of this problem is the use of fluoride containing restorative materials. The ability of a material to inhibit secondary caries formation is an important clinical therapeutic property. This investigation assessed the capacity of esthetic restorative materials to resist caries in vitro. Class V cavities were prepared in buccal and lingual surfaces of 50 extracted sound third molars. The occlusal and gingival cavosurface margin of each preparation was on enamel surface. The five materials were used: Conventional glass ionomer cement Ceramfil beta (PSP), two polyacid modified resin composites Compoglass (Vivadent) and Dyract (Dentsply/DeTrey), non fluoride releasing composite resin Valux Plus (3M) and fluoride releasing composite resin Tetric (Vivadent). After 10 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned occluso-gingivally through the middle of the restorations and examined by polarized light microscopy, while immersed in water. The statistical analysis of the results showed that secondary caries initiation and progression might be reduced significantly when fluoride-containing materials were placed. The conventional glass ionomer cement (Ceramfil beta) provided the highest protection against caries attack and the non-fluoride releasing composite resin (Valux Plus) restoration provided the least (p<0.05).