Caries-free Individuals Research Articles

Dermatoglyphic findings in dental caries and their correlation with salivary levels of Streptococcus mutans and Lactobacillus in school-going children in and around Moradabad.

Introduction:Dental caries is the disease of the calcified tissues of the teeth resulting from the action of microorganisms on carbohydrates characterized by a decalcification of inorganic portion of the tooth and accomplished or followed by disintegration of organic portion. Genetic susceptibility to dental caries is dependent on certain factors, which, if evaluated, can help in estimating disease situation prematurely. Dermatoglyphics are the genetically determined dermal ridge configurations on the digits, palms and soles, influenced by environmental forces that are operating before birth. Hence, the study was undertaken to establish a possible link between dental caries and dermatoglyphics and to determine whether specific dermatoglyphic patterns exist which help in predicting the occurrence of dental caries.Subjects and Methods:The dermatoglyphics of 50 caries free (CF) and 50 individuals with dental caries (WDC) were taken and compared with the microbial levels of Streptococcus mutans and lactobacilli, and results were evaluated qualitatively and quantitatively.Statistical Analysis:Analysis was done using P value, Chi-square test and Student's t-test.Results and Conclusion:(1) Whorl pattern was more common in individuals WDC (P < 0.0001) as compared to the CF individuals who exhibited more loop pattern (P = 0.002). (2) Whorl pattern had significant association with the microbial counts of S. mutans (P = 0.383) and Lactobacillus (P = 0.015) with no such statistically significant correlation with loop pattern in the disease group. (3) ≤6 loops was a good predictor of caries. ≥4 whorls was a moderate predictor of caries.

Site-specific plaque pH before and after short-term use of 1.5% Arginine dentifrice in caries-free and caries-active individuals

ABSTRACTObjective: To examine the pH response to an acidic challenge in site-specific plaque following a six-week period of using toothpaste consisting of 1.5% arginine and 1450 ppm fluoride or just using 1450 ppm fluoride toothpaste alone, in relation to caries.Methods: Thirty-three healthy adults with no caries (caries-free) or ≥1 current manifest lesion (caries) participated in the study. Interproximal plaque-pH was measured in four sites. Two-weeks after professional cleaning, pH-measurements were performed before and up to 15-min after a 1-min rinse with 10 ml of a 10% sucrose solution. This procedure was repeated after a 6-week test period of using randomly selected toothpaste with 1.5% arginine and fluoride or with fluoride alone. The stimulated salivary flow rate was determined and the salivary-pH and buffer capacity was measured.Results: In the caries group, the use of toothpaste with arginine and fluoride resulted in increased pH-values in the four sites tested. Although it was not statistically significant, increased pH-values were found in the caries-free group. In addition, the whole saliva buffer capacity and pH was increased in the caries group.Conclusion: The most pronounced effect on plaque-pH and stimulated saliva after using arginine and fluoride toothpaste was seen in the caries group.

Health-Associated Niche Inhabitants as Oral Probiotics: The Case of Streptococcus dentisani.

Oral diseases, including dental caries and periodontitis, are among the most prevalent diseases worldwide and develop as a consequence of a microbial dysbiosis. Several bacterial strains are being tested as potential oral health-promoting organisms, but usually they are species isolated from niches other than the site where they must exert its probiotic action, typically from fecal samples. We hypothesize that oral inhabitants associated to health conditions will be more effective than traditional, gut-associated probiotic species in key aspects such as colonization of the oral site where disease takes place or the possession of oral health promoting functions, as well as more practical issues like safety and toxicity, and establishing proper doses for administration. As an example of these active colonizers, we describe the case of Streptococcus dentisani, a new streptococcal species isolated from dental plaque of caries-free individuals. We have detected it in 98% of dental plaque samples from healthy individuals and, as expected, it does not produce any toxic secondary metabolite and does not survive a simulated stomach digestion, preventing potential secondary effects. Besides, this species has a double probiotic action, as it inhibits the growth of major oral pathogens through the production of bacteriocins, and also buffers acidic pH (the primary cause of dental caries) through an arginolytic pathway. We propose the use of S. dentisani as a promising probiotic against tooth decay.

Twin-city Study correlating the Dermatoglyphic Patterns with Rampant Caries and Early Childhood Caries

ABSTRACT Introduction Dermatoglyphics is the scientific and analytical study of fingerprints. Every individual's fingerprints are distinctive; one can determine one's ingrained potential, individuality, and choices by interpreting dermatoglyphics. This twin-city survey was undertaken to evaluate the fingerprint patterns of children with dental caries [study groups – rampant caries vs early childhood caries (ECC)] and caries-free individual (control group). Aim This study was carried out to determine the correlation between dermatoglyphic pattern and caries prevalence in young children in the twin cities of Pune and Mumbai. Materials and methods Two centers were selected in Pune and Mumbai. A total of 300 patients (150 patients in each center) were randomly selected from the age group ranging between 3 and 5 years. The samples were divided into two groups: Group I: Caries group, and group II: Caries-free group. Group I was further divided into children with ECC and children with rampant caries. Clinical examination of dental caries was done using mouth mirror and probe (only to remove debris and not probe into the fissures) in daylight or suitable light source. Fingerprints were obtained by the conventional ink method. Statistical results were obtained by one-way analysis of variance with post hoc Tukey's correction for multiple group comparisons using Statistical Package for the Social Sciences version 20. Results The evaluation and comparison of patterns in children with caries and caries-free children in both right and left hands showed increase in the number of whorls in children with rampant caries as compared with children with ECC. However, this was not statistically significant. Conclusion The study showed a definite variation in dermatoglyphics between the ECC, rampant caries, and caries-free group. However, the rampant caries group showed more number of whorls as compared with the ECC group, but they were statistically insignificant. Dermatoglyphics has proven to be a useful, noninvasive, and cost-efficient tool for investigating diseases with a genetic background like dental caries and cleft lip and palate, etc. How to cite this article Chunawala Y, Morawala A, Ambiye A, Jain K. Twin-city Study correlating the Dermatoglyphic Patterns with Rampant Caries and Early Childhood Caries. Int J Clin Dent Res 2017;1(1):1-4.

Salivary microbiota in individuals with different levels of caries experience

ABSTRACTThis study compared salivary bacterial profiles in two groups having a 10-fold difference in levels of caries experience, as it was hypothesized that the composition of the salivary microbiota might associate with the levels of caries experience.Bacterial profiles in stimulated saliva samples from 85 individuals with low levels of caries experience (healthy group) and 79 individuals with high levels of caries experience (caries group) were analyzed by means of the Human Oral Microbiome Identification Next Generation Sequencing (HOMINGS) technique. Subsequently, saliva samples from caries-free individuals in the healthy group (n = 57) and the caries group (n = 31) were compared.A significantly higher α-diversity (p < 0.0001) and a twofold higher relative abundance of Neisseria, Haemophilus, and Fusobacterium were recorded in saliva samples from the healthy group compared with the caries group. Differences observed were more pronounced when limiting the analyses to caries-free individuals in each group.Data from this cross-sectional analysis suggest that low levels of caries experience might associate with a characteristic salivary bacterial composition different from that in individuals with high caries experience. Consequently, longitudinal studies are required to determine if the composition of the salivary microbiota might be a predictive factor of caries risk at the individual level.

The clinical performance of chairside caries risk assessment kits.

Caries risk assessment is an important component of clinical practice. The goal of this project was to evaluate the diagnostic performance of two commercially available kits (the Saliva-Check mutans and the Plaque-Check pH kit; GC-America) in distinguishing caries-active from caries-free individuals. The effect of following instructions not to eat, drink, or perform oral hygiene, prior to testing, was also investigated on the effectiveness of these kits. The subjects included 26 caries-affected children and 20 caries-free adults. Plaque and saliva samples were collected for analysis by the two kits following the manufacturer's instructions. For 63 additional subjects, instructions not to eat, drink, or practice oral hygiene were omitted prior to sample collection. The sensitivity and specificity in distinguishing caries-free from caries-active subjects was calculated for both kits. The sensitivity (88%) and specificity (90%) of the Saliva-Check mutans kits were satisfactory in the subjects refraining from eating etc. In contrast, both the sensitivity and the specificity of this kit were reduced when subjects were tested without use instructions. When tested in subjects that followed instructions, the pH kit's sensitivity and specificity were 72% and 55% respectively. This modest diagnostic performance was reduced when pH values were measured in subjects not following use instructions. These kits, particularly the Saliva-Check mutans kits, can contribute to patient education by documenting microbial caries risk factors. Though difficult to implement in practice, subjects should refrain from eating or other activities that disturb the oral environment prior to sample collection.

Exploration of bacterial species associated with the salivary microbiome of individuals with a low susceptibility to dental caries.

Dental caries is caused by acidogenic plaque microbiota formed on saliva-bathed tooth surfaces, in which multiple organisms act collectively to initiate and expand a cavity. We explored bacterial species associated with the salivary microbiome of individuals with low susceptibility to dental caries. The bacterial composition of saliva from 19 young adults was analyzed using barcoded pyrosequencing of the 16S rRNA gene; we compared 10 caries-experienced (CE) and nine caries-free (CF) individuals.Aquantitative PCR assay of salivafrom 139 orally healthy adults aged 40-59years was carried outto confirm the result obtained by pyrosequencing analysis. The microbiomes of CF individuals showed more diverse communities with a significantly greater proportion of the genus Porphyromonas. Among operational taxonomic units (OTUs) corresponding to the genus Porphyromonas, the OTU corresponding to P. pasteri was the most predominant and its relative abundance in CF individuals was significantly greater than in CE individuals (P<0.001, Wilcoxon rank sum test). A quantitative PCR assay of saliva confirmed that the amounts of P. pasteri were significantly higher in individuals with lower caries experience (filled teeth <15, n=67) than in those with higher caries experience (filled teeth ≥15, n=72) (P<0.001, Student's t test). These results revealed an association between a greater abundance of P. pasteri and lower susceptibility to dental caries. P. pasteri may be a bacterial species that could potentially be used as a marker for maintaining a healthy oral microbiome against dental caries.

Analysis of Bacterial Activity in Sound and Cariogenic Biofilm: A Pilot in vivo Study

Dental caries is a multifactorial disease with many associated microbial taxa, but only a few are notably contributing to acidogenicity. The ribosome number and the corresponding 16S ribosomal RNA (rRNA) concentration are considered a molecular indicator for general metabolic activity of bacteria, as they are elevated with increased anabolic and catabolic activities. We hypothesize that the activity of aciduric/acidogenic bacterial taxa, reflected by a rise in ribosomal counts, could resolve differences between plaque biofilm from sound surfaces and caries lesions. The included subjects were allocated to two groups: caries-free (CF) or caries-active (CA). CF subjects presented one donor site, namely one sound surface (CFS, n = 10), whereas CA subjects presented two donor sites: a cavitated lesion with an ICDAS score of 5-6 (CAC, n = 13), and a sound reference surface (CAS, n = 13). Four aciduric/acidogenic bacterial taxa (Streptococcus mutans, lactobacilli, Bifidobacterium dentium, and Scardovia wiggsiae) and one asaccharolytic taxon (fusobacteria) as a contrast were selected. 16S rRNA and 16S rRNA genes were quantified by quantitative PCR. Based on these parameters, bacterial and ribosomal counts, as well as relative activities were calculated as the quotient of relative ribosomal abundance and relative genome abundance. Caries-associated bacteria showed the highest relative activity in caries lesions (e.g. lactobacilli CAC: 177.5 ± 46.0%) and lower activities on sound surfaces (e.g. lactobacilli CAS: 96.3 ± 31.5%), whereas asaccharolytic fusobacteria were most active on sound surfaces and less active in caries lesions (CFS: 275.7 ± 171.1%; CAS: 205.8 ± 114.3%; CAC: 51.1 ± 19.0%). Thus, the present study suggests different activity patterns for biofilms from CF and CA individuals.

Identification of ssDNA aptamers specific to clinical isolates of Streptococcus mutans strains with different cariogenicity.

Streptococcus mutans, a Gram-positive facultative anaerobic bacterium, is considered to be a major etiological factor for dental caries. In this study, plaques from dental enamel surfaces of caries-active and caries-free individuals were obtained and cultivated for S. mutans isolation. Morphology examination, biochemical characterization, and polymerase chain reaction were performed to identify S. mutans The cariogenicity of S. mutans strains isolated from clinical specimens was evaluated by testing the acidogenicity, aciduricity, extracellular polysaccharide production, and adhesion ability of the bacteria. Finally, subtractive SELEX (systematic evolution of ligands by exponential enrichment) technology targeting whole intact cells was used to screen for ssDNA aptamers specific to the strains with high cariogenicity. After nine rounds of subtractive SELEX, sufficient pool enrichment was achieved as shown by radioactive isotope analysis. The enriched pool was cloned and sequenced randomly, followed by MEME online and RNA structure software analysis of the sequences. Results from the flow cytometry indicated that aptamers H1, H16, H4, L1, L10, and H19 could discriminate highly cariogenic S. mutans strains from poorly cariogenic strains. Among these, Aptamer H19 had the strongest binding capacity with cariogenic S. mutans strains with a dissociation constant of 69.45±38.53 nM. In conclusion, ssDNA aptamers specific to highly cariogenic clinical S. mutans strains were successfully obtained. These ssDNA aptamers might be used for the early diagnosis and treatment of dental caries.

Influence of the Inoculum Source on the Cariogenicity of in vitro Microcosm Biofilms

This study investigated the cariogenic potential of biofilms originating from different types of inoculum (saliva and dental plaque) from caries-active and caries-free individuals. Ten volunteers were selected from each caries condition for the paired collection of saliva and dental plaque. Microcosm biofilms were grown in triplicate from each inoculum on enamel specimens in 24-well plates under cariogenic challenge. After 10 days, the biofilms were collected for analysis of outcome variables: percentage of surface hardness change (%SHC) and microbiological composition of biofilms. Statistical analysis was performed using the t test, the linear multivariate analysis model and Pearson's correlation coefficients (α = 0.05). A comparative analysis between microbiological baseline data showed higher counts of mutans streptococci in plaque samples within caries-active individuals; a comparative analysis of colony-forming unit (CFU) counts between individuals with different caries status showed higher counts of acid-tolerant microorganisms and mutans streptococci in dental plaque and of acid-tolerant microorganisms in saliva. After 10 days of biofilm growth, the CFU values for total microorganisms, lactobacilli, mutans streptococci and acid-tolerant bacteria, as well as for SHC, were not statistically significant, considering the type of inoculum and caries condition (p > 0.05). A positive correlation was found for %SHC and CFU counts of acid-tolerant bacteria (r = 0.406) and lactobacilli (r = 0.379). Under the limits of this study, the cariogenic potential of biofilms, formed under identical conditions in vitro, is similar, regardless of baseline differences between the source and type of inoculum.

A Highly Arginolytic Streptococcus Species That Potently Antagonizes Streptococcus mutans.

The ability of certain oral biofilm bacteria to moderate pH through arginine metabolism by the arginine deiminase system (ADS) is a deterrent to the development of dental caries. Here, we characterize a novel Streptococcus strain, designated strain A12, isolated from supragingival dental plaque of a caries-free individual. A12 not only expressed the ADS pathway at high levels under a variety of conditions but also effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans. A12 produced copious amounts of H2O2 via the pyruvate oxidase enzyme that were sufficient to arrest the growth of S. mutans. A12 also produced a protease similar to challisin (Sgc) of Streptococcus gordonii that was able to block the competence-stimulating peptide (CSP)-ComDE signaling system, which is essential for bacteriocin production by S. mutans. Wild-type A12, but not an sgc mutant derivative, could protect the sensitive indicator strain Streptococcus sanguinis SK150 from killing by the bacteriocins of S. mutans. A12, but not S. gordonii, could also block the XIP (comX-inducing peptide) signaling pathway, which is the proximal regulator of genetic competence in S. mutans, but Sgc was not required for this activity. The complete genome sequence of A12 was determined, and phylogenomic analyses compared A12 to streptococcal reference genomes. A12 was most similar to Streptococcus australis and Streptococcus parasanguinis but sufficiently different that it may represent a new species. A12-like organisms may play crucial roles in the promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens.

The influence of glycemic control on the oral health of children and adolescents with diabetes mellitus type 1.

To evaluate the influence of disease control, expressed by the mean values of glycated hemoglobin (HbA1c), in the oral health of children and adolescents with diabetes mellitus type 1 (T1DM). A cross sectional study involving 87 children and adolescents (59 girls), 10 ± 2.6 years old. The participants were divided into three groups: HbA1c ≤ 8%, 8% < HbA1c ≤ 10% and HbA1c > 10%. The duration of the disease, age and average HbA1c were obtained from their medical records. Oral health was evaluated according to the following indexes: Simplified Oral Hygiene Index (OHI-S); Community Periodontal Index (CPI); Decayed, Missing or Filled Teeth Index (DMFT/dmft) for permanent and deciduous teeth; and the stimulated salivary flow rate (SSFR). The median SSFR was 1.1 mL/min in the group with HbA1c ≤ 8%, 0.7 mL/min in the intermediary group and 0.6 mL/min in the HbA1c > 10% group. A significant decrease in salivary flow was observed with an increase in HbA1c (p = 0.007). The DMFT/dmft and CPI indexes were higher in individuals with higher HbA1c values. More caries-free individuals were found in the group with HbA1c ≤ 8% compared to those with HbA1c > 10%. The group with HbA1c > 10% exhibited more caries and bleeding gums than the other groups. HbA1c values in girls were higher than in boys. Children and adolescents with unsatisfactory glycemic control, represented by higher HbA1c concentrations, exhibited a higher frequency of caries and gingivitis, and a reduction in salivary flow.

Study on relationship between the nutritional status and dental caries in 8-12 year old children of Udaipur City, India.

The future health of individuals depends on the well being of the children of today. Proper nutrition for children is very important. The most commonly used index of obesity and over weight is Body Mass Index. The growth of children should be monitored using the Body Mass Index (BMI) and risk factors assessed through a dietary and physical activity history. The increase in obesity is attributed to increased carbohydrate consumption among children. Obesity and caries are both diet-based conditions that share a cause that is, excessive ingestion of fermentable carbohydrates. This study was undertaken to determine the association of nutritional status with dental caries in 8 to 12 year old children of Udaipur city. The present study was conducted on a random sample of 1000 boys and girls, aged 8-12 years. The children were selected from schools located in the Udaipur City, Rajasthan. The schools examined were of government and private sector schools in Udaipur city. The children from schools of Udaipur city was taken in the study with male, female and age group ratio as per distribution in population. A proforma was used to record children's age, gender, school, year, height, weight, parental income and dental caries status. Statistical analysis was done using Statistical Package of Social Science (SPSS Version 15; Chicago Inc., USA). It was found that caries free individuals were more from normal nutritional status group with 134 (13.4 %) subjects where as only 11 (1.1 %) of subjects obese children were found caries free. Study shows that the children with normal BMI for age had more caries in their primary teeth, as well as in their permanent teeth, than the overweight children.

DD Genotype of ACE I/D Polymorphism Might Confer Protection against Dental Caries in Polish Children

The aim of the study was to examine the frequencies of the genotypes and alleles of ACE insertion/deletion (I/D) polymorphism and their association with dental caries in a sample of Polish children. The study subjects were 120 children with dental caries experience (cases) and 41 caries-free individuals (controls). The genotyping was performed using polymerase chain reaction. The genotype distributions of ACE I/D polymorphism were not statistically different between carious and control children. However, we found a borderline overrepresentation of the II + ID genotypes versus the DD genotype in the carious compared to the control group (69.2% and 51.2%, respectively, p = 0.057). Logistic regression analysis adjusted for age and sex revealed that I allele carriage was a significant predictor of dental caries susceptibility (OR = 2.14, 95% CI = 1.02-4.49, p = 0.041). In conclusion, the DD genotype of ACE I/D polymorphism might be protective against dental caries in Polish children.

Weaker dental enamel explains dental decay.

Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is “weaker” while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

Investigation of salivary function and oral microbiota of radiation caries-free people with nasopharyngeal carcinoma.

Radiation caries have been reported to be correlated with radiotherapy-induced destruction of salivary function and changes in oral microbiota. There have been no published reports detailing patients who have remained radiation caries-free following radiotherapy for nasopharyngeal carcinoma. The aim of this study was to investigate the relationship between salivary function, oral microbiota and the absence of radiation caries. Twelve radiation caries-free patients and nine patients exhibiting radiation caries following irradiated nasopharyngeal carcinoma were selected. V40, the dose at which the volume of the contralateral parotid gland receives more than 40 Gy, was recorded. Stimulated saliva flow rate, pH values and buffering capacity were examined to assess salivary function. Stimulated saliva was used for molecular profiling by Denaturing Gradient Gel Electrophoresis. Mutans streptococci and Lactobacilli in saliva were also cultivated. There were no significant differences in V40 between radiation caries-free individuals and those with radiation caries. Compared with normal values, the radiation caries-free group had significantly decreased simulated saliva flow rate, while there were no significant differences in the saliva pH value and buffering capacity. Similar results were observed in the radiation caries group. There was no statistical difference in microbial diversity, composition and log CFU counts in cultivation from the radiation caries-free group and the radiation caries group. Eleven genera were detected in these two groups, among which Streptococcus spp. and Neisseria spp. had the highest distribution. Our results suggest that changes in salivary function and in salivary microbiota do not explain the absence of radiation caries in radiation caries-free individuals.

Transcriptomic analysis of three Veillonella spp. present in carious dentine and in the saliva of caries-free individuals.

Veillonella spp. are predominant bacteria found in all oral biofilms. In this study, a metatranscriptomic approach was used to investigate the gene expression levels of three oral Veillonella spp. (V. parvula, V. dispar and V. atypica) in whole stimulated saliva from caries-free volunteers and in carious lesions (n = 11 for each group). In the lesions the greatest proportion of reads were assigned to V. parvula and genes with the highest level of expression in carious samples were those coding for membrane transport systems. All three Veillonella spp. increased expression of genes involved in the catabolism of lactate and succinate, notably the alpha- and beta-subunits of L(+)-tartrate dehydratase (EC 4.2.1.32). There was also significantly increased expression of histidine biosynthesis pathway in V. parvula, suggesting higher intra-cellular levels of histidine that could provide intra-cellular buffering capacity and, therefore, assist survival in the acidic environment. Various other systems such as potassium uptake systems were also up regulated that may aid in the survival and proliferation of V. parvula in carious lesions.

Contextual and individual determinants of dental pain in preschool children.

Despite growing interest on dental pain in children, there are very few studies on its prevalence and determinants among preschool children. The objective of this study was to assess prevalence of dental pain and associated individual and contextual factors in 5 year-old Brazilian children. This cross-sectional study used primary data from the 2010 National Survey of Oral Health, carried out in capital cities and a sample of country towns. Participants were 7280 5-year-olds, who were examined in their homes and whose parents answered a questionnaire. Dependent variable was report of dental pain in the last 6 months. Independent variables were contextual (city level) socioeconomic factors, and individual (child) sociodemographic and oral health-related variables. Data analysis included hierarchized Poisson regression models, using a multilevel approach and prevalence rate (PR) estimates. The prevalence of dental pain was 22.0% (95% CI 19.1-25.2). It was higher among those living in cities with lower human development index (PR 0.07; 95% CI 0.02-0.22) and with a higher percentage of their population with an incomplete primary education (PR 1.03; 95% CI 1.01-1.06). Indigenous children had prevalence of dental pain 1.97 times higher (95% CI 1.19-3.26) than those of white colour. Families with monthly incomes of U$ 218.00 or less and between U$ 219.00 and U$ 656.00 had, respectively, a prevalence of dental pain 2.67 (95% CI 1.33-5.32) and 2.11 (95% CI 1.03-4.32) times higher than families with highest income level. For each unit increase in the number of dwellers per bedroom, there was a 14% increase in the probability of having pain. Children with caries experience had a 3.45 (95% CI 2.58-4.62) higher prevalence of pain than caries-free individuals. Dental pain prevalence in Brazilian preschool children was high and influenced by contextual and individual factors.

Effect of sucrose concentration on sucrose-dependent adhesion and glucosyltransferase expression of S. mutans in children with severe early-childhood caries (S-ECC).

Sucrose, extracellular polysaccharide, and glucosyltransferases (GTFs) are key factors in sucrose-dependent adhesion and play important roles in the process of severe early-childhood caries (S-ECC). However, whether sucrose concentration regulates gtf expression, extracellular polysaccharide synthesis, and sucrose-dependent adhesion is related to the different genotypes of S. mutans isolated from ECC in children and still needs to be investigated. In this study, 52 strains of S. mutans were isolated from children with S-ECC and caries-free (CF) children. Water-insoluble glucan (WIG) synthesis was detected by the anthrone method, adhesion capacity by the turbidimetric method, and expression of gtf by RT-PCR in an in vitro model containing 1%–20% sucrose. The genotypes of S. mutans were analyzed by AP-PCR. The results showed that WIG synthesis, adhesion capacity, and gtf expression increased significantly when the sucrose concentration was from 1% to 10%. WIG synthesis and gtfB as well as gtfC expression of the 1% and 5% groups were significantly lower than those of the 10% and 20% groups (p < 0.05). There were no significant differences between the 10% and 20% groups. The fingerprints of S. mutans detected from individuals in the S-ECC group exhibited a significant difference in diversity compared with those from CF individuals (p < 0.05). Further, the expression of gtfB and gtfC in the S-ECC group was significantly different among the 1- to 5-genotype groups (p < 0.05). It can be concluded that sucrose-dependent adhesion might be related to the diversity of genotypes of S. mutans, and the 10% sucrose level can be seen as a “turning point” and essential factor for the prevention of S-ECC.

Dental plaque pH and ureolytic activity in children and adults of a low caries population

Objectives. The aim of this study was to evaluate the plaque pH level and ureolytic activity among children and adults of Karen Hill tribes. Methods. Thirty-four children aged 6–10 years and 46 adults aged 20–38 years were interviewed regarding oral hygiene practices, sucrose intake and betel chewing. Caries experience (DMFT and DT), calculus, bleeding on probing (BoP) and Plaque index (PlI) were registered. Ureolytic activity in supragingival plaque was tested at two interproximal sites (11/12 and 41/42) with the rapid urease test (RUT). Registration of plaque pH was performed at two interproximal sites (15/16 and 31/41) before, during and 30 min after rinsing with an urea solution (0.25%). Four interproximal plaque samples (one from each quadrant) per individual were collected to test the bacterial composition using the checkerboard technique. Results. Children and adults had similarly low DMFT and DT values. Children had a higher baseline pH and a higher ureolytic activity in the maxilla (p < 0.05) compared with adults. A significant correlation (r2 = 0.63) was found between baseline pH and urease activity in the mandibular anterior teeth. Caries-free individuals had a higher baseline pH compared with caries active individuals in the anterior mandibular region (p < 0.01). The microbiological composition was characterized by an anaerobic low acidiogenic microbiota. Conclusions. Dental plaque pH is related to the ureolytic activity, which explains the low acidogenic plaque microflora and the low caries levels in the Karen population.