Subsequent Caries Research Articles

Separation of an effective fraction from turmeric against Streptococcus mutans biofilms by the comparison of curcuminoid content and anti-acidogenic activity

Turmeric has long been used as a colouring and flavouring agent for foods. Curcuminoids are the main component of turmeric and have a range of pharmacological activities. In this study, a fraction that could show anti-biofilm activity was separated from turmeric, based on a comparison of curcuminoid content and anti-acidogenic activity against Streptococcus mutans, and the effects of the separated fraction and curcuminoids on the adherence ability of S. mutans and the physiological ability of S. mutans biofilms were examined at sub-minimum inhibitory concentration (MIC) levels. The separated fraction and curcuminoids had inhibitory effects on the sucrose-dependant adherence of S. mutans to saliva-coated hydroxyapatite (sHA) discs and the acidogenicity and aciduricity of S. mutans biofilms. These results suggest that the separated turmeric fraction and its components, curcuminoids, may be useful for controlling dental biofilms and subsequent dental caries formation.

Caries in primary molars of 6–7-year-old Turkish children as risk indicators for future caries development in permanent molars

Background/purpose The aim of the present study was to investigate whether caries existence in the primary dentition at the age of 6-7 years can serve as a test to predict subsequent caries in the permanent first molars. Clinical examinations were carried out in suboptimal conditions of a school-based screening, where non-cavitated enamel caries could not be recorded. Materials and methods Caries were recorded at baseline and 4 years later in 286 Turkish children aged 6-7 years old. Spearman's correlation coefficients between variables of the caries experience of the primary dentition at the age of 6-7 years and caries in the permanent first molars at the age of 10-11 years were calculated. The area under the ROC curve was used as a measure of predictive accuracy. Results Caries experience of the primary dentition (dmft), primary molars (dmft molars), and primary second molars (dmft 2nd molars) showed a statistically significant correlation with caries (DMFT) 4 years later in the permanent first molars. Among the variables, the caries experience of the primary second molars was the most powerful caries predictor, which resulted in a value of 0.69 under the ROC curve. Conclusion With the selection criterion “dmft2ndmolars = 0” in this low-caries-incidence pediatric population, it was possible to identify children truly negative for misclassification.

Bioactivity-guided separation of anti-acidogenic substances againstStreptococcus mutansUA 159 fromPolygonum cuspidatum

The aim of this study was to separate the anti-acidogenic substances against Streptococcus mutans UA 159 from Polygonum cuspidatum. The anti-acidogenic substances were separated by a series of liquid-liquid fractionations followed by normal-phase silica gel liquid chromatography, based on high-performance liquid chromatography and glycolytic pH-drop assay. The effectiveness of the separated substances on the acidogenicity of Streptococcus mutans UA 159 was examined using sodium fluoride as a positive control. The chemical composition and quantities of the components of the substances was also assessed by qualitative-quantitative chromatographic analysis. Among the substances separated from P. cuspidatum, F3 showed the strongest inhibitory effect on the acidogenicity of S. mutans UA 159 in a dose-dependent manner without displaying any bactericidal activity. F3 decreased the acidogenicity of S. mutans even at 12.5 microg ml(-1) (P < 0.05). F3 consisted mainly of resveratrol and emodin (C(14)H(12)O(3) and C(14)H(4)O(2)(OH)(3)CH(3), respectively), which made up approximately 60% of the weight of F3. F3 can be considered as a promising agent for controlling the acidogenicity of S. mutans and subsequent dental caries formation.

Exploring the contributions of components of caries risk assessment guidelines

To examine the relative contribution of current caries activity, past caries experience, and dentists' subjective assessment of caries risk classifications. Administrative data from two dental plans were analyzed to determine dentists' risk classification, as well as current caries activity and previous caries experience at the time of the classification. The performance of these predictors in identifying patients who would experience subsequent caries was then modeled using logistic regression. In both plans, current caries activity alone had relatively low sensitivity and high specificity in identifying patients who would experience subsequent caries. Sensitivity improved, but at the cost of specificity when previous caries experience was included in the models. Further improvement in sensitivity accrued when dentists' subjective assessment was included, but performance was different in the two plans in terms of false-positives. Consideration of previous caries experience tends to strengthen the predictive power of caries risk assessments. Dentists' subjective assessments also tend to improve sensitivity, but overall accuracy may suffer.

In vitro effects of a fraction separated from Polygonum cuspidatum root on the viability, in suspension and biofilms, and biofilm formation of mutans streptococci

Polygonum cuspidatum (Polygonaceae) has traditionally been used in folk medicine to control oral diseases. Nevertheless, there are no reports related to its possible effect on the diseases, particularly on biofilm-related diseases such as dental caries. In this study, we evaluated in vitro effects of a fraction separated from Polygonum cuspidatum root on the viability, in both suspension and biofilms, and the biofilm formation of mutans streptococci. The separated fraction (F1) showed bacteriostatic and bactericidal activity against mutans streptococci in suspension, with minimum inhibitory concentration (MIC) range of 31.3–250 μg/ml and minimum bactericidal concentration (MBC) range of 0.5–1 mg/ml. At a concentration of 1.5 mg/ml, F1 killed approximately 2 log 10 CFU/ml of Streptococcus mutans and Streptococcus sobrinus after 2 h of exposure. In biofilms, F1 also inhibited the viability of Streptococcus mutans and Streptococcus sobrinus, dependent on the biofilm age, the concentration of F1, and the treatment time. Four hours of exposure to 1.5 mg/ml F1 reduced the viable counts of Streptococcus mutans and Streptococcus sobrinus by greater than 2 log 10 CFU/disc. Furthermore, at sub-MIC levels, F1 inhibited biofilm formation by Streptococcus mutans and Streptococcus sobrinus in a dose-dependent fashion. Based on the preliminary phytochemical analysis, the activity of F1 may be related to the presence of anthraquinones, cardiac glycosides, terpenoids, and phenolics. These results indicate that F1 is probably useful in the control of oral biofilms and subsequent dental caries development.

In vitro inhibitory effects of Polygonum cuspidatum on bacterial viability and virulence factors of Streptococcus mutans and Streptococcus sobrinus

Polygonum cuspidatum has been used in Korean folk medicine to improve oral hygiene. This study was performed to evaluate the effects of methanol extract from root of P. cuspidatum (MEP) on bacterial viability and the virulence factors of Streptococcus mutans and Streptococcus sobrinus. To test the effects of MEP on bacterial viability, we determined the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 20 bacterial strains, including S. mutans and S. sobrinus, using a micro-dilution assay. In case of S. mutans and S. sobrinus, the assays for time-kill and bacterial growth rate at sub-MIC concentrations were also performed. To determine effects of the extract on the virulence factors of S. mutans and S. sobrinus, the assays for sucrose-dependent adherence, water-insoluble glucan formation, glycolytic acid production, and acid tolerance were performed at sub-MIC levels. Phytochemical analysis for constituents of MEP was carried out. MEP showed a broad antibacterial range (MIC 0.5-4 mg/ml). The MBC was two to four times higher than the MIC. The time-kill curves showed S. mutans and S. sobrinus were significantly killed after 1h of incubation. At sub-MIC levels, doubling times of S. mutans and S. sobrinus dose-dependently increased up to 211% and 123%, respectively. At sub-MIC levels, MEP also showed inhibitory effects on the virulence factors of S. mutans and S. sobrinus in a dose-dependent fashion. Phytochemical analysis revealed the presence of alkaloids, sterol/terpenes, tannins, flavonoids, and carbohydrates. These data indicate that MEP has inhibitory effects on bacterial viability at higher concentrations (> or =MIC) and the virulence factors of S. mutans and S. sobrinus at sub-MIC concentrations, suggesting that it might be useful for the control of dental plaque formation and subsequent dental caries formation.

In vitro anti-cariogenic activity of dichloromethane fraction fromRheum undulatum L. root

This study aimed to evaluate in vitro effects of Rheum undulatum L. root on the development of dental caries, especially its effects on viability, dental plaque formation, and glycolytic acid production of Streptococcus mutans and Streptococcus sobrinus. Methanol extract of Rheum undulatum L. root and its fractions were prepared and tested. Among the test extract and fractions, dichloromethane fraction (DF) showed the most active antibacterial activity (inhibition zone: 13-17 mm) against S. mutans and S. sobrinus in a disc diffusion method. Minimal inhibitory concentrations (MICs) of DF against these bacteria ranged from 0.25 to 0.5 mg/mL. Furthermore, DF significantly inhibited the caries-inducing factors of these bacteria. At sub-MIC levels, DF inhibited in vitro dental plaque formation by S. mutans and S. sobrinus (IC50= 0.079 and 0.142 mg/mL, respectively), which was caused, in part, by the inhibitory effect on the activity of glucosyltransferases. A significant reduction of glycolytic acid production was found at the concentration as low as 0.032 mg/mL for S. mutans and 0.063 mg/mL for S. sobrinus. The possible bioactive compounds that are inducing in vitro anti-cariogenic activity of DF are unknown. Based on the preliminary phytochemical analysis, the activity of DF may be related to the presence of anthraquinones, cardiac glycosides, coumarines, sterols/terpenes, and phenolics. These results indicate that DF is probably useful for the control of dental plaque formation and subsequent dental caries development.

Caries increment in the permanent dentition of Mexican children in relation to prior caries experience on permanent and primary dentitions

To evaluate the likelihood of caries increment in schoolchildren, based on their prior caries experience. We undertook a longitudinal study in 452 six-to-nine year olds between 1999 and 2001 in Mexico, with dental exams conducted by two standardized examiners (kappa>0.85). The dependent variable was the DMFT increment, dichotomized as without increment, and at least one unit of increment. Independent variables estimated caries experience at baseline. Data were analyzed using non-parametric tests and generalized linear models (log-binomial) to calculate relative risk (RR) adjusted for age and sex. The percentage of caries-free children diminished by 20.5% from 1999 to 2001. DMFT index increased two-fold, from 0.25+/-0.70 in 1999 to 0.77+/-1.30 in 2001 (p<0.001). The overall risk for this sample was 24%. The DMFT increment was higher (p<0.001) in children with DMFT>0 and dmft>0 in 1999 (RR=1.89, 95% CI=1.37-2.62; RR=2.71, 95% CI=1.94-3.76, respectively). The likelihood for DMFT increment from the 1999 levels was: (1) 2.78 times higher (95% CI=2.06-3.76) if schoolchildren had caries in any of the first permanent molars and (2) 1.62 times higher (95% CI=1.20-2.19) if schoolchildren were affected by high severity caries at baseline. Both caries prevalence and mean DMFT had significant increments in 18 months. Dental caries in the primary (dmft) and permanent (DMFT) dentitions at baseline are goods indicators of subsequent caries development in this group of children in a medium income country. This relationship became stronger when the occurrence of caries in the first permanent molars was included.

Targeted supervised toothbrushing reduces caries increment

Design Randomised Controlled TrialIntervention Supervised toothbrushing on schooldays with 1000 ppm fluoride toothpaste with toothpaste and brushes supplied for home use one class in each school was allocated to intervention and compared to a within-school control over a 2-year period. Dental examinations were performed by a single-blinded examiner at 6-monthly intervals.Outcome measure Visual examinations of caries at D1 level (all visible cavitated and non-cavitated lesions in enamel and dentine). Approximal and occlusal surfaces were also examined using Fibre-optic transillumination (FOTI).Results 86% of those examined at baseline completed study. At baseline children in both groups had similar levels of oral cleanliness; however, children from the more deprived areas had poorer levels of cleanliness. There was no significant difference between the groups in the caries increment in the deciduous teeth after 2 years. Dental immaturity had a significant effect on subsequent caries development. After 2 years there was a significantly less caries in the permanent molars in the intervention group, with 32% fewer D1 lesions (95% CI 4–60%) and 56% fewer D3 lesions (95% CI 13–101%).Conclusions A targeted supervised toothbrushing programme with support for home use resulted in a significant reduction in caries increment.

Does a clinical evaluation of oral cleanliness correlate with caries incidence in preschool children? Findings from a cohort study.

The aim of this study was to assess whether a clinical evaluation of oral cleanliness reflects subsequent caries incidence. Oral examination of 180 children (1- to 4-year-olds) was carried out twice in a six-month period. Caries prevalence at baseline (dfs) in 1- to 2-year-olds (group A) and 3- to 4-year-olds (group B) correlated significantly with oral cleanliness as well as salivary mutans streptococci count (MS). Caries increment (delta(dfs)) correlated significantly with oral cleanliness in group A but not in group B, while delta(dfs) significantly correlated with MS in group B and slightly correlated with that in group A. ANCOVA revealed that dfs was significantly higher at the second examination than at baseline in group B, even after adjusting for oral cleanliness. This finding was confirmed by Wilcoxon test when group B was divided in three categories (low, middle and high) based on oral cleanliness. This suggests that the relationship between delta(dfs) and oral cleanliness decreased with age and that the significant positive correlation found in group B by our point-prevalence survey is derived from the remainder of the positive correlation that occurred at a younger age.

Lack of Effect of Chlorhexidine Varnish on Streptococcus mutans Transmission and Caries in Mothers and Children

In a randomized clinical trial, we evaluated the effect of a 10% chlorhexidine varnish (Chlorzoin^®) on the mother-child transmission of Streptococcus mutans and on subsequent caries experience. Chlorhexidine (n = 38) or a placebo varnish (n = 37) was applied to the dentitions of 75 mothers at a time when their first babies were about 6 months old (approximate time of first tooth emergence). Three more applications at weekly intervals and subsequent applications at 6-month intervals followed the initial application. The mother-child pairs were followed up until the child’s fourth birthday. Maternal salivary S. mutans levels in the treatment group remained significantly lower (p < 0.05) compared to the control group up to 12 months after the initial application. However, this intervention did not significantly alter the S. mutans colonization in children or the caries increment in either the mother or the child.

A FINITE ELEMENT STRESS ANALYSIS OF THE INTERFACE STRESS GENERATED DURING THE PUSH-OUT TEST

Within the dental sphere it is advantageous to be able to bond the restoration to dentine in order to avoid clinical problems such as marginal leakage with subsequent caries. Dentine bonding agents are normally employed to create an effective interface between the restoration and hard tissue with the formation of chemical links. The measurement of the bond strength between dental restorations or implants and surrounding hard tissue is generally achieved through the use of an experimental push-out test. However, these bond strengths have been found to be quite variable between laboratories even when similar chemical bonding agents have been used. This variability may be due to a number of factors including experimental differences such as, material moduli effects, specimen loading and changes in the thickness and properties of the interdiffusional zone (IDZ) that forms following polymerization of the bonding agent. In this work, these variables have been explored using the finite element method initially through a 2-D description of the geometrical set up and subsequently a 3-D discretization. The results indicate that the loading and specimen support during testing have a significant effect on the measured push-out values. Furthermore the effects of a gradually changing modulus in the uppermost rings of the IDZ can have a significant influence on the support bearing property of the bonding agent. These changes in modulus of the IDZ may be the result of fluoride leaching to bring about increases in properties and modulus. A mixed moduli IDZ where the uppermost layer is approximately double the value of the remaining material can lead to increases in push-out values of 10% or more.

A vaccine against dental caries: an overview.

Dental caries continues to be a costly and prevalent oral disease. Research efforts towards developing a well tolerated and effective vaccine against dental caries were initiated following the demonstration of a specific bacterial aetiology for this disease. The cariogenic mutans streptococci are the principal bacteria causing this disease. Specific immune defence against these bacteria is provided mainly by secretory immunoglobulin (Ig) A antibodies present in saliva, which are generated by the common mucosal immune system. Progress in the development of a vaccine against dental caries has increased due to both advancements in molecular biology and our understanding of the mucosal immune system and mucosal vaccines. Advancements in molecular biology have facilitated the cloning and functional characterisation of virulence factors of the mutans streptococci, including the cell-surface fibrillar proteins, which mediate adherence to the tooth surface, and the glucosyltransferase enzymes, which synthesise adhesive glucans and allow microbial accumulation on the teeth. Current strategies for immunisation against dental caries are using these virulence factors as key antigens and incorporating them into novel mucosal vaccine systems and delivering them with or without adjuvants to mucosal IgA inductive sites. The most popular routes of mucosal immunisation are via the oral or nasal route. The mucosal immune system is functional in newborn infants, who develop salivary IgA antibodies as they become colonised by oral micro-organisms. Mucosal immunisation strategies result in the induction of salivary IgA antibody responses and pose fewer problems than parenteral injection of antigen. Therefore, mucosal immunisation of infants prior to the appearance of their first teeth may be a well tolerated and effective way to induce immunity against the colonisation of teeth by mutans streptococci and protection against subsequent dental caries. The purpose of this article is to provide an overview of the recent progress on the development of a vaccine against infection by Streptococcus mutans for the prevention of dental caries, with emphasis on the mucosal immune system and vaccine design.

Fundamental Interactions of Laserswith Dental Hard Tissues

Summary In order to choose the laser conditions that will be best suited for a particular application in dentistry, knowledge of the fundamental interactions of lasers with the tissues is necessary. Lasers interactions with tissue are complicated and no single parameter alone will determine how the laser affects the tissue. Dental hard tissue applications include ablation of carious lesions, cavity preparation for restoration, caries detection, endodontic surgery, and the potential for caries preventive therapy. The parameters of prime concern in understanding desirable or undesirable tissue effects are wavelength, pulse duration, absorption properties, scattering, energy, fluence (energy/surface area), power density, repetition rate, number of pulses, pulse duration and pulse shape. A range of laser parameters has been found with which dental enamel can be treated to make it resistant to subsequent dissolution by acid during dental caries. Our studies have demonstrated that treatment of enamel by specific pulsed carbon dioxide laser irradiation can markedly inhibit subsequent caries progression. During irradiation, heat causes carbonate loss from the carbonated hydroxyapatite mineral, converting it into a low solubility hydroxyapatite-like calcium phosphate. By carefully choosing the parameters it is possible to produce a laser that can selectively remove carious tissue, leading to a conservative cavity preparation, and also providing protection against later caries challenges.

Assessing caries risk in children.

With the dramatic improvements in the oral health of children in Australia that have occurred over the past two decades, the option of, and the need for, targeted prevention of dental caries for those at high risk has become apparent. Since caries is of multifactorial aetiology, the clinical outcome varies depending on which factor, or combination of factors, is prominent in a particular individual; this may be related to both age and stage of life. Tests for caries risk can assist in prediction, but clinical signs and history are as important in assessing the main cause(s) of caries in an individual. In studies involving several factors, past caries experience (especially of the first permanent molar) continues to be the best predictor of future caries in children. Despite their ready availability, tests in the form of commercial kits are still expensive; no one test is an adequate predictor of caries risk, and the specificity and sensitivity of the tests are not reliably diagnostic for an individual. There is a need for regional longitudinal risk assessment studies in which potential risk factors are identified before the onset of caries in order to maximize predictive power and then validated against subsequent caries. Caries activity may not be able to be predicted in a population with low disease prevalence. Any risk assessment strategy must be followed by appropriate preventive interventions.

Chromosomal deletions in Streptococcus mutans.

The oral bacterium Streptococcus mutans possesses the ability to ferment a wide range of carbohydrates, which results in the production of acids that can cause demineralisation of tooth enamel and subsequent dental caries. However, it has been shown that approximately 11% of independent isolates of S. mutans from around the world lack the ability to ferment melibiose, raffinose, and on occasion β-glucosides (1,4). This is due to a deletion which extends through a region of the genome that includes the multiple sugar metabolism (msm) operon involved in the uptake and metabolism of a number of sugars (3). The msm region has been reintroduced to the deletion mutants by transformation and the ability to grow on galactose and β-glucosides was also restored, showing the linkage of the respective genes. The extent of the deletion is further being investigated with the use of pulsed field gel electrophoresis and Southern hybridizations with known S. mutans genes as probes.

Advanced Techniques of Micro-Analysis and Confocal Microscopy: Perspectives for Studying Chemical and Structural Changes at the Interface Between Restorative Materials and the Cavity Wall

Migration of trace amounts of elements and structural changes characterize the interface between immiscible substances. The contact zone among filling materials, saliva, and the cavity wall has the additional function of preventing the progress of leakage and subsequent caries. Difficulties in chemically and structurally analyzing the gradients of composition in an interface of microscopic dimensions characterize the experimental situation. The use of advanced techniques of instrumental micro-analysis and techniques of micro-visualization is our approach to the problem. With confocal laser scanning microscopy (CLSM), effects of the components of the filling material on the structure of the cavity wall can be visualized non-destructively. Surface analysis with electron spectroscopy (XPS) and micro-spot analysis with laser mass analysis (LASMA) give the information on changes of the elemental composition of the cavity wall. The effects of the filling materials on the structure of enamel are correlated with the pre-treatment of the cavity wall. XPS and LASMA give evidence that fluoride does not migrate into the enamel of the cavity wall.

Residual effects of fluoride on a severe cariogenic challenge in rats.

The influence of temporary dietary restriction with and without fluoridated drinking water on the progression of caries was studied in 60 desalivated Sprague-Dawley rats. Dietary restriction alone had little effect on caries progression when the challenge was interrupted and then resumed, in contrast to the effects of dietary restriction plus fluoride. Animals subjected to gavage plus fluoride in the drinking water for 11 days developed significantly less severe lesions on their lingual surfaces than did any of the other groups. No significant differences were observed in the microbial flora of the animals at the end of the study. The results show that temporary dietary restriction alone has little permanent effect on caries progression and that fluoride administered even for a short time in the absence of cariogenic challenge has a statistically significant, but probably less than optimum, protective effect against a subsequent caries challenge.

Age differences in stable carbon and nitrogen isotope ratios in a population of prehistoric maize horticulturists

Stable carbon isotope ratios in prehistoric human bone collagen have been used extensively to document the introduction and intensification of maize horticulture in notheastern North America. Most previous studies are based on small samples of adults who are assumed to characterize the diet of the population. In this study, all 29 individuals buried within an Ontario Iroquoian village site dated A.D. 1530-1580 were analysed for stable isotopes of carbon and nitrogen. Age distribution of the sample ranges from preterm to elderly. Significant negative correlations between age and delta 13C, and age and delta 15N values were found. High delta 13C values in infants and young children (delta 13C = -6.8 to -12.3) suggest a weaning diet high in maize. High delta 15N values in infants relative to adults suggest a trophic level effect during breast-feeding which has been reported in a modern sample by Tuross et al. (Am. J. Phys. Anthropol., 1993). In addition to the isotopic evidence for extremely high carbohydrate (maize) intake, the MacPherson sample includes two juveniles aged 3-4 years, exhibiting circular caries. No other cases of this condition are known in the extensively studied southern Ontario skeletal collections. Together the evidence from dentition and stable carbon isotopes indicates a very high carbohydrate diet in subadults. Circular caries result from developmental stress during enamel formation with subsequent caries formation in areas of thinner enamel. These findings are relevant to studies of infant and early childhood morbidity and mortality among prehistoric maize horticulturists.

The relationship between the biochemical composition of dental plaque from both approximal and free smooth surfaces of teeth and subsequent 3-year caries increment in adolescents

The biochemical composition of both types of plaque and the subsequent caries increment were investigated in 39 males aged 11–12 years at the time of plaque collection. The calcium concentration of free smooth-surface plaque was inversely related to both total and approximal 3-year DFS increment ( p < 0.01). A relationship between calcium concentrations in approximal plaque and subsequent caries was restricted to the 3-year increment on approximal surfaces ( p < 0.05). There was evidence for a direct relationship between caries increment and both magnesium and organic phosphorus concentrations in plaque on the free smooth surfaces only ( p < 0.05). In contrast, a direct relationship between total caries increment and both total and intracellular carbohydrate concentrations reached statistical significance for approximal plaque only ( p < 0.05). Regression analysis indicated that the combination of the calcium and inorganic phosphorus concentrations of free smooth-surface plaque and the intracellular carbohydrate concentrations of approximal plaque explained 40% of the variation in subsequent caries increment.