Genotypic and phenotypic analysis of Streptococcus mutans from different oral cavity sites of caries‐free and caries‐active children

Introduction: Streptococcus mutans exhibits extensive genotypic diversity, but the role of this variation is poorly understood. This study aimed to determine the number and distribution of genotypes of S. mutans isolated from caries‐active and caries‐free children and to evaluate some of their phenotypic traits. Methods: Stimulated saliva, tongue surface and biofilms over sound and carious teeth surfaces were sampled from 10 caries‐free and 11 caries‐active children aged 5–8 years. A total of 339 isolates of S. mutans were genotyped by arbitrarily primed polymerase chain reaction using OPA2 primer. One isolate from each genotype was tested for its acid susceptibility and its ability to form a biofilm. Results: Fifty‐one distinct genotypes were determined, one to three genotypes in each oral sample. A single genotype was detected in seven children, whereas the remaining 14 children exhibited two to seven genotypes. There were no significant differences in the number of genotypes detected in caries‐free and caries‐active children. No correlation was observed between the number of genotypes and the mutans streptococci salivary levels. Five of the six high biofilm‐forming genotypes were obtained from caries‐active children, although the differences in biofilm formation between isolates from caries‐free and caries‐active children were not statistically significant. Genotypes with low susceptibility to acid challenge were statistically more frequent among isolates from caries‐active children than among those from caries‐free children. Conclusion: The present data suggested that there were differences in the distribution of genotypes of S. mutans according to the oral site and that S. mutans populations differ in their acid susceptibility and ability to form biofilms, factors allowing their colonization of sucrose‐rich environments.     

Determination of mutacin activity and detection of mutA genes in Streptococcus mutans genotypes from caries‐free and caries‐active children

Relationships between genetic diversity, mutacin production and sensitivity to mutacins in Streptococcus mutans were evaluated in 19 clinical isolates from caries‐free and caries‐active children. Mutacin production was tested against 30 indicator strains; results showed significant variations in the inhibitory spectra of the clinical isolates. There was no association between the inhibitory spectrum of the infecting strain and the caries experience or the level of mutans streptococci infection of the host. Homology to the mutA gene coding for mutacin II was detected in one clinical isolate; none of the clinical isolates showed homology to the mutA genes coding for mutacins I or III. Genotyping by random amplified polymorphic DNA (RAPD) reactions grouped the isolates into three clusters, but no correlation was found between any of the clusters and mutacin activity, caries experience or level of mutans streptococci in the host.     

Dental caries and caries-associated microorganisms in Uruguayan preschool children

The prevalence of dental caries was studied in 3-5-year-old Uruguayan children (n = 76) living in 2 areas with different socioeconomic and cultural conditions. More children from the low socioeconomic area of Las Acacias had caries (68%) than children from the middle- to high-class neighborhood of Pocitos (19%). They also had poorer oral hygiene and a significantly higher caries prevalence (P < 0.05) than those from Pocitos. The occurrence of mutans streptococci and lactobacilli was determined in whole unstimulated saliva and compared with that in debris collected with a loop from the dorsum of the tongue. Mutans streptococci were detected in 42% of the children with significant correlations between the salivary levels of the microorganism and caries experience. Lactobacilli were recovered less frequently (18%). The detection of mutans streptococci in the tongue-loop samples was significantly correlated with that in whole saliva.     

The relationship between sweetness preference, levels of salivary mutans streptococci and caries experience in Brazilian pre-school children

Aim . To analyse the relationship between preference for sweetness, levels of salivary mutans streptococci and levels of caries in low socio-economic 4–5-year-old Brazilian children.
Design . A cross-sectional survey.
Subjects and methods . 298 children of both sexes, who, in 1998, were regularly attending public nurseries were randomly selected. Caries experience was assessed according to WHO guidelines. Saliva samples were analysed for mutans streptococci using the spatula method. Children's preference for sugar was measured using the 'Sweet Preference Inventory'. Personal interviews with the mothers were conducted.
Results . 255 children completed all aspects of the research, a response rate of 85·6%. 34·9% of them were caries-free. The mean dmf-s was 4·25 (SD 6·16), the decayed component being 3·56 (SD 5·82) and the filled surfaces, 0·69 (SD 1·85). For these pre-school children; male sex ( P < 0·01), single parent ( P < 0·01), habit of eating or drinking items that contained non-milk extrinsic sugar between meal times ( P < 0·05) and high levels of salivary mutans streptococci ( P < 0·001) were significantly associated with higher dmfs scores. There was no statistical relationship between sweetness preference and dental caries and with mutans streptococci levels.
Conclusion . Levels of salivary mutans streptococci but not sweetness preference were potential good predictors of caries experience among 4–5 years-old-children living in urban area of Brazil.     

Differential adhesion of Streptococcus mutans to metallic brackets induced by saliva from caries‐free and caries‐active individuals

Aim: The purpose of this study was to evaluate the influence of saliva obtained from caries‐free and caries‐active individuals on the adhesion rates of Streptococcus mutans to metallic brackets. Methods: The unstimulated whole saliva of four caries‐free (decayed, missing, or filled surfaces = 0) volunteers and four caries‐active (decayed, missing, or filled surfaces >12) patients were collected. The saliva samples from each group were mixed and clarified. Acquired pellicles were formed onto 30 metallic edgewise brackets for premolars for each saliva group. The brackets were put in contact with planktonic cells of Streptococcus mutans ATCC 25175. Adhesion rates were assessed by crystal violet retention technique. Results: A higher streptococcal adhesion pattern (P < 0.00001) was observed on acquired pellicles formed by saliva from caries‐active donors. Conclusions: The results showed that saliva from caries‐active patients tends to increase the mutans adhesion to surfaces, which is a point of concern for orthodontists.     

Individual risk assessment of caries

The estimation of individual caries risk factors and the related preventive treatment in the dental practice are discussed. Salivary counts of mutans streptococci and lactobacilli reflect the bacteriological attack (mutans streptococci) and sugar intake (lactobacilli). Caries resistance can be estimated by measurement of the salivary secretion rate and buffer capacity. Treatment of high caries risk patients should be directed against etiological factors. Salivary flow rates and buffer capacity can be stimulated by daily (sugar-free) gum-chewing. For the use of fluoridated toothpaste and sugar intake the dentist is dependent upon the cooperation of the patient. The bacteriological factor in the caries process can be suppressed by application of chlorhexidine varnish.     

Mutans streptococci, lactobacilli and caries experience in 12-year-old Icelandic urban children, 1984 and 1991

Abstract In order to evaluate changes in salivary counts of cariogenic bacteria and relate these to trends in caries experience, stimulated saliva was collected from a 20% random sample of 12-yr-old residents of Reykjavik. Iceland (252 children) in 1991 under conditions consistent with those of a survey conducted in 1984. The mean and median counts of salivary mutans streptococci and lactobacilli remained similar in the two studies. However, the frequency distribution at lower levels of mutans streptococci differed significantly between 1991 and 1984, e.g. in the present study 25.8% of the children had < 10⁵ compared with 13.8% in the study 1984. The mean caries prevalence in the permanent dentition (DFS_tot) was 11.0, which is significantly lower than in 1984 (mean DFS_tot 28.8). A significant difference in caries prevalence was found at various levels of salivary mutans streptococci. Strep. mutans (serotype c/e/f) was carried by all mutans streptococci-positive children, save one child, who carried only Strep. sobrinus. The proportion of 12-yr-olds who carried Strep, sobrinus had decreased significantly to 15.7% from 34.0% in 1984. Significantly more children with Strep. sobrinus showed high levels of total mutans streptococci than children with only Strep. mutans. As the case was in 1984 significantly more Strep. sobrinus carriers had a high level of salivary lactobacilli as well as higher caries prevalence than the children who did not carry this species.     

Dental caries and caries-associated microorganisms in Uruguayan preschool children

The prevalence of dental caries was studied in 3-5-year-old Uruguayan children (n = 76) living in 2 areas with different socioeconomic and cultural conditions. More children from the low socioeconomic area of Las Acacias had caries (68%) than children from the middle- to high-class neighborhood of Pocitos (19%). They also had poorer oral hygiene and a significantly higher caries prevalence (P < 0.05) than those from Pocitos. The occurrence of mutans streptococci and lactobacilli was determined in whole unstimulated saliva and compared with that in debris collected with a loop from the dorsum of the tongue. Mutans streptococci were detected in 42% of the children with significant correlations between the salivary levels of the microorganism and caries experience. Lactobacilli were recovered less frequently (18%). The detection of mutans streptococci in the tongue-loop samples was significantly correlated with that in whole saliva.     

A cross-sectional study into the prevalence of root caries in periodontal maintenance patients

Abstract. The aim of this cross-sectional study was to investigate cross-sectionally the prevalence and several risk indicators of root caries in 45 periodontal maintenance patients, who had been actively treated for adult periodontitis 11–22 years ago. These patients were part of a routine 3–6 monthly maintenance schedule. Active and inactive root caries and root fillings were recorded, as well as coronal caries experience. Plaque and bleeding scores, number of exposed root surfaces, rate of saliva secretion, saliva buffering capacity, mutans streptococci counts and Lactobacilli were also scored. From the total of 45 study subjects, 37 patients (82%) showed root lesions (root caries and/or root fillings), while only 8 patients were free of any root lesions. On average, there were 4.3 root lesions per patient (range 0–19) in the present study. 10 patients had active root caries lesions. Of all damaged root surfaces, 9% were active lesions, mostly located on mandibular teeth at lingual and vestibulair sites; 40% were inactive lesions often detected at vestibular sites. The remaining damaged root surfaces (51%) were restored; they were equally divided over both jaws. A higher number of root lesions was observed in those patients with >10⁶mutans streptococci/ ml saliva. Although the actual number of lesions per patient was low in relation to the large number of sites with gingival recession, the results from this cross-sectional study in periodontal maintenance patients indicate that: (1) root caries can be regarded as a complication in periodontal maintenance patients; (2) the individual number of root lesions correlate with individual dental plaque scores; (3) a high number of root lesions is associated with high counts of salivary mutans streptococci; (4) no relation between root caries and coronal caries experience, salivary secretion rate or salivary buffering capacity seems present. Therefore, repeated oral hygiene instructions and adjunctive preventive measures including diet counseling and fluoride rinses, as well as fluoride and chlorhexidine varnishes, should be advocated in high-risk patients.     

Salivary mutans streptococci and dental caries patterns in pre-school children

Abstract Recent studies have suggested that the identification of caries as discrete patterns may be valuable in describing and predicting caries experience on an individual basis. The purpose of this study was to assess the association between levels of salivary mutans streptococci and the prevalence, incidence and distribution of caries patterns in the primary dentition. A cohort of pre-school children (n=146, mean age 3.8 yr) were examined for dental caries and sampled for salivary mutans streptococci (SMS) at baseline and once annually for 2 yr. Children's tooth surfaces were categorized into four patterns: pit/fissure, maxillary anterior, posterior proximal, and buccal/lingual smooth surface. Salivary mutans streptococci were enumerated using a tongue blade technique, and were categorized as low (0 CPU), moderate (1–50 CPU) and high (>50 CPU). At year 2, children with high baseline SMS had the 1) highest prevalence of caries (87%) and the highest dmfs (9.15); 2) highest prevalence of each pattern, and 3) greatest number of patterns. Among children with the pit/fissure pattern, those with high baseline SMS had the greatest pit/fissure dmfs after 2 yr. Results show that baseline SMS levels were associated with both cross-sectional and longitudinal caries experience, numbers of caries patterns, and the prevalence and severity of those patterns.     

Streptococcus mutans infection level and caries in a group of 5-year-old children

The level of Streptococcus mutans in stimulated saliva and its association with caries experience was evaluated in 149 5-year-old children. In general, salivary S. mutans levels were low, and it was detected only in 46% of saliva samples. There was, however, a clear association between salivary levels of S. mutans and caries experience (chi 2 = 53.65, p less than 0.001). Salivary examination was supplemented with plaque samples in 47 children. The number of S. mutans positive surfaces increased with increasing salivary levels. S. mutans was most often isolated and comprised the highest proportion in the approximal samples. The number of children with high salivary S. mutans levels was very low (6%) when taken into account that 13% of the children were fairly caries active (dmfs greater than or equal to 5). This most probably means that in evaluation of caries risk, the salivary S. mutans screening level is different in preschool children and in older children. The level should be determined in longitudinal studies before applying to preschool children.     

Salivary microflora and caries experience in 5-year-old children from two ethnic groups

The purposes of the study were threefold: to compare salivary levels of mutans streptococci and Lactobacillus in 140 5-year-old children from two ethnic groups, to correlate caries experience of each group with bacterial counts, and to determine levels of infectivity which could indicate high caries activity in young children. Pakistani-Muslim and white Caucasian children were paired, matched for age, gender and caries experience. There were no significant differences in mutans streptococci or Lactobacillus levels between the two ethnic groups. However, strong correlations were found between caries experience and levels of both mutans streptococci and Lactobacillus in each ethnic group. Furthermore, mutans streptococci and Lactobacillus levels correlated strongly with one another. For detection of high caries activity, the optimum screening levels of bacteria were > 10(5) cfu/ml for mutans streptococci (sensitivity 78% and specificity 86%) and > 10(4) cfu/ml for Lactobacillus (sensitivity 82% and specificity 89%).     

Nitric oxide modulates levels of salivary Lactobacilli

Abstract

Objective. Nitric Oxide (NO) is one of the most powerful antibacterial compounds. The aim of this study was to determine the association between salivary NO, dental caries and cariogenic bacteria. Materials and methods. The salivary NO concentration of 257 Korean children was analyzed by the Griess colorimetric reaction method. Salivary mutans streptococci (MS) and Lactobacilli (LB) were counted using the Dentocult MS and Dentocult LB kit, respectively. Dental caries status was examined using the WHO criteria. Confounders were age, gender, salivary flow rate and salivary buffer capacity. Analysis of covariance (ANCOVA) was used to evaluate the association among NO, salivary MS level, salivary LB level and dental caries status after adjusting for the effects of confounders. Results. A significant decrease was found in salivary NO levels as the salivary LB count increased after controlling for confounders (p = 0.049). However, the MS level, caries experience and active caries status showed no significant association. Conclusion. This result indicates that NO production might be a host defense mechanism against the growth of cariogenic bacteria.     

学龄前儿童乳牙龋相关因素的分析

目的 评价学龄前儿童的唾液变形链球菌、唾液流速和缓冲力、口腔卫生状况、饮食和口腔卫生习惯、母亲文化程度和职业等因素在乳牙龋发生中的意义.方法 采用病例对照研究方法,对1018名4岁和5岁儿童进行龋齿检查,其中dmft≥6的204人构成高龋组,dmft=0的237人为无龋组.测定两组儿童唾液变形链球菌水平、唾液流速和缓冲力、软垢指数,并由儿童母亲回答统一问卷.结果 共有417名儿童纳入结果的统计中.Logistic回归分析结果显示,唾液变形链球菌(OR=3.019)、软垢指数(OR=2.263)、每天吃甜食次数(OR=1.729)、每天喝甜饮料次数(OR=1.496)、奶瓶内容物含糖(OR=2.255)等因素有意义.结论 唾液变形链球菌水平高、口腔卫生差、高频率摄入甜食、奶瓶喂养时内容物含糖是乳牙龋的重要危险因素.     

Dental caries increments and related factors in children with type 1 diabetes mellitus

The aim of this study was to analyse possible associations between caries increments and selected caries determinants in children with type 1 diabetes mellitus and their age- and sex-matched non-diabetic controls, over 2 years. A total of 63 (10-15 years old) diabetic and non-diabetic pairs were examined for dental caries, oral hygiene and salivary factors. Salivary flow rates, buffer effect, concentrations of mutans streptococci, lactobacilli, yeasts, total IgA and IgG, protein, albumin, amylase and glucose were analysed. Means of 2-year decayed/missing/filled surface (DMFS) increments were similar in diabetics and their controls. Over the study period, both unstimulated and stimulated salivary flow rates remained significantly lower in diabetic children compared to controls. No differences were observed in the counts of lactobacilli, mutans streptococci or yeast growth during follow-up, whereas salivary IgA, protein and glucose concentrations were higher in diabetics than in controls throughout the 2-year period. Multivariable linear regression analysis showed that children with higher 2-year DMFS increments were older at baseline and had higher salivary glucose concentrations than children with lower 2-year DMFS increments. Likewise, higher 2-year DMFS increments in diabetics versus controls were associated with greater increments in salivary glucose concentrations in diabetics. Higher increments in active caries lesions in diabetics versus controls were associated with greater increments of dental plaque and greater increments of salivary albumin. Our results suggest that, in addition to dental plaque as a common caries risk factor, diabetes-induced changes in salivary glucose and albumin concentrations are indicative of caries development among diabetics.     

Correlation among mutans streptococci counts, dental caries, and IgA to Streptococcus mutans in saliva

Two-hundred and forty individuals were studied, divided into five groups as follows: caries-free children, children with caries, children with rampant caries, young adults with and without caries. Whole stimulated saliva was collected and all individuals were investigated for DMFT/dmft according to the WHO criteria and the simplified oral hygiene index (OHI-S). Quantitative analysis of the total aerobic flora and mutans streptococci in saliva was performed. Also, the level of salivary anti-S. mutans IgA was determined by ELISA. Children with rampant caries showed the highest OHI-S value. The highest total counts of microorganisms were found in the group of children with caries. No statistically significant differences were observed for salivary flow, OHI-S and microorganism counts between the groups of young adults. No correlation between mutans streptococci counts and anti-Streptococcus mutans IgA levels was observed in the studied groups. A correlation between increased anti-Streptococcus mutans IgA levels and caries-free status was observed among young adults but not among children.     

Diet intake and caries prevalence in four-year-old children living in a low-prevalence country

Preventive measures have dramatically decreased the prevalence of dental caries in children. However, risk factors for the disease in children living in low-prevalence areas remain elusive. In the present study we evaluated associations between dental caries, saliva levels of mutans streptococci and lactobacilli, and diet with special emphasis on the intake of fermentable carbohydrates and dairy products in 4-year-old children living in an area where the overall caries prevalence was low. Dietary intake was recorded in 234 infants as part of the Study of Infant Nutrition in Ume?, Sweden (SINUS). Of these the parents of 124 children gave consent to participate in a follow-up at 4 years of age. Dietary intake, height and weight, dental caries, oral hygiene, including tooth brushing habits, presence of plaque and gingival inflammation, fluoride habits and numbers of mutans streptococci and lactobacilli in saliva were recorded. Using multivariate stepwise logistic regression, caries experience was negatively associated with intake frequency of cheese (OR = 0.67; 95% CI = 0.44-0.98) and positively associated with the salivary level of mutans streptococci (OR = 1.57; 95% CI = 1.21-2.03). Caries experience was not correlated with intake frequency or amounts of carbohydrate-containing foods, with any other particular food, or with daily intake of energy, carbohydrate or any other macro- or micronutrient. We conclude that cheese intake may have a caries-protective effect in childhood populations where the overall caries prevalence and caries experience are low and the children are regularly exposed to fluoride from toothpaste.     

Antimicrobial peptides in saliva of children with severe early childhood caries

ObjectiveControversies exist regarding the relationship between the concentrations of antimicrobial peptides (AMPs) and presence of dental caries in children. Thus, the aim of this study was to examine levels of AMPs in saliva of caries-free (CF), early childhood caries (ECC) and severe early childhood caries (S-ECC) children to determine if the levels of these salivary peptides individually or in combinations were related to caries severity and mutans streptococci levels.Design36 to 60 month-old children were selected to participate in this study. Children were grouped into CF group (n = 29), ECC group (n = 25) and S-ECC group (n = 29). Saliva was collected from children for microbiological analysis by culture. Salivary concentrations of cathelicidin LL-37, human β-defensin 2 (hBD-2), human β-defensin 3 (hBD-3) and histatin-5 (HTN-5) were determined by ELISA.ResultsSalivary concentrations of AMPs did not differ among CF, ECC and S-ECC groups. Data showed positive correlations between mutans streptococci levels and salivary hBD-2 or HTN-5. Positive correlations were found between hBD-2, hBD-3, LL-37 and HTN-5. Combinations among AMPs, mainly LL-37, were positively associated with caries levels.ConclusionsSalivary concentrations of AMPs individually were not associated with the severity of early childhood caries. The stimulus of caries appears to trigger a biological response, however, with a combination of these peptides.     

Caries prevalence and salivary mutans streptococci in 0–2-year-old children of Japan

The prevalence of caries and the number and species distribution of salivary mutans streptococci in 356 children (aged 0-2 yr old) in Japan were examined twice at an interval of 1 yr. No mutans streptococci were isolated from the predentate children. The detection rate of mutans streptococci and the prevalence of caries increased with age. Mutans streptococci were isolated from 39.9% of the subjects. The majority of isolates were identified as Streptococcus mutans. The concentration of mutans streptococci correlated with the number of erupted teeth (r = 0.339). In addition, the concentration of mutans streptococci was more closely correlated to the caries prevalence of the next year (r = 0.465) than that of the year when the salivary concentration of mutans streptococci was first evaluated (r = 0.368). The children who had no caries but harbored mutans streptococci in the first year showed significantly higher caries prevalence in the next year than did the children with neither caries nor mutans streptococci. These results indicate that the establishment of mutans streptococci is associated with caries initiation in early childhood.     

Two-year longitudinal observations of salivary status and dental caries in children with insulin-dependent diabetes mellitus.

Salivary status and caries incidence were studied in 28 young, Type 1 diabetics from the onset of the disease and during a two-year period. Flow rate, buffer capacity, glucose content, total protein concentration and levels of mutans streptococci and lactobacilli were determined in stimulated whole saliva every third month. Dental caries was recorded at onset and then once a year. Forty-six per cent of the children developed caries during the observation period. Caries incidence was significantly higher (P less than 0.05) during the first year of diabetes, compared with the second. Caries-active children displayed significantly higher HbA1c levels (P less than 0.001), compared with caries-inactive diabetics. The number of salivary lactobacilli dropped significantly (P less than 0.05) during the first six months of the disease, while mutans streptococci levels remained unchanged during the study period. Salivary glucose concentration showed a considerable individual variation, but tended to be lower during the second year. The results suggest a possible relationship between Type 1 diabetes treatment and caries.