Mutans streptococci, lactobacilli and caries prevalence in 11- and 12-year-old Icelandic children

Streptococcus mutans, Streptococcus sobrinus and Candida albicans in oral samples from caries-free and caries-active children

AIM

This was to examine the occurrence of S. mutans, S. sobrinus and C. albicans in dental plaque and saliva from caries-free and caries-active Greek children.

METHODS

Saliva and dental plaque samples from 46 caries-free and 51 caries-active 3-to-13-year-old children were examined using selective media for the three microbes. Identification of isolated mutans streptococci (S. mutans and S. sobrinus) was performed with biochemical test and specific DNA probes. The salivary levels of mutans streptococci were additionally determined by a chair-side test (Dentocult^® SM strips).

RESULTS

The isolation frequencies of S. mutans, S. sobrinus and C. albicans were 66, 11 and 18 %, respectively. Caries-active children harboured more frequently and at significantly higher numbers the specific microbes than caries-free children. A similar pattern was observed with the Dentocult^® SM strip scores. No correlation was found between the presence of these microbes and the age or gender of the children.

CONCLUSIONS

Caries experience was statistically significantly related to the presence of all three microbes under study, both in dental plaque and saliva.

Longitudinal study of dental caries incidence associated with Streptococcus mutans and Streptococcus sobrinus in patients with intellectual disabilities

Background

Mutans streptococci (Streptococcus mutans and S. sobrinus) are considered to be major etiologic agents of dental caries. Using a polymerase chain reaction method, we detected those bacteria from 145 outpatients (6–30 years old) with intellectual disabilities (ID) and their presence was compared with the incidence of dental caries.

Methods

Plaque samples were collected from all erupted tooth sites in subjects with a sterile toothbrush. A dental examination was performed to determine the number of decayed and filled teeth (DFT score) in permanent dentition using the WHO caries diagnostic criteria. A Mann–Whitney U-test was employed to compare the caries scores between combinations of the bacteria, and with a Wilcoxon rank test used to compare caries scores between the baseline and after 1 year.

Results

Among all subjects, S. mutans and S. sobrinus were possessed by 78.7 and 83.5 %, respectively, while 13.1 % were positive for S. mutans alone, 17.9 % for S. sobrinus alone, and 65.6 % for both organisms, with 3.4 % were negative for both. The mean DFT score of subjects positive for both S. mutans and S. sobrinus at after 1 year was significantly higher than that of those positive for S. mutans alone (P < 0.01). The increase in caries increment was also significantly greater in subjects with both bacteria detected (P < 0.001).

Conclusion

Our results indicate that patients with ID harboring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.

Effect of oil gum massage therapy on common pathogenic oral microorganisms - A randomized controlled trial

Objectives:

(i) To assess reduction in Streptococcus mutans and Lactobacillus species count in saliva sample after ten minutes of oil gum massage therapy (massage of gingival tissues) per day for three weeks with sesame oil, olive oil, and coconut oil in three different groups of subjects. (ii) To compare the efficacy between three different oils and the “gold standard” chlorhexidine gel. (iii) To assess reduction in gingival scores and plaque scores of study subjects.

Materials and Methods:

Study design – Single center, parallel design, and triple blind randomized clinical study with four treatment groups. Participants: 32 of the 40 study subjects working as housekeeping personnel at Kasturba Hospital, Manipal; aged 18-55 years completed the three-week study period. Interventions: Subjects were randomly assigned to massage their gingiva everyday for three weeks with sesame oil, olive oil, coconut oil (tests), and Chlorhexidine gel (control). Oral health status and paraffin stimulated saliva samples were obtained at baseline and after three weeks of oil gum massage therapy. Outcome measures: Microbial culture, plaque index, and gingival index. Statistical analysis: Paired t test and Kruskal Wallis test.

Results:

There was a significant reduction in mean Streptococcus mutans count, Lactobacillus count, plaque scores, and gingival scores in all four groups after the study. However, there was no significant difference found in percentage reduction of these variables between the four groups.

Conclusion:

These oils can be used as valuable preventive agents in maintaining and improving oral health in low socioeconomic status population. However, it is recommended that further research should be conducted in other populations with a larger sample and longer duration of follow-up period.

Identification of Lactobacillus from the saliva of adult patients with caries using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) has been presented as a superior method for the detection of microorganisms in body fluid samples (e.g., blood, saliva, pus, etc.) However, the performance of MALDI-TOF MS in routine identification of caries-related Lactobacillus isolates from saliva of adult patients with caries has not been determined. In the present study, we introduced a new MALDI-TOF MS system for identification of lactobacilli. Saliva samples were collected from 120 subjects with caries. Bacteria were isolated and cultured, and each isolate was identified by both 16S rRNA sequencing and MALDI-TOF MS. The identification results obtained by MALDI-TOF MS were concordant at the genus level with those of conventional 16S rRNA-based sequencing for 88.6% of lactobacilli (62/70) and 95.5% of non-lactobacilli (21/22). Up to 96 results could be obtained in parallel on a single MALDI target, suggesting that this is a reliable high-throughput approach for routine identification of lactobacilli. However, additional reference strains are necessary to increase the sensitivity and specificity of species-level identification.

Microbiological evaluation of salivary Streptococcus mutans from children of age 5-7 years, pre- and post-atraumatic restorative treatment

Background and Objective:

The objective of the study was to monitor Streptococcus mutans (SM) counts in saliva of children aged 5-7 years old over a period of 6 months with the subsequent use of Fuji IX, glass ionomer cement in atraumatic restorative technique (ART).

Materials and Methods:

One hundred children were selected to receive ART using Fuji IX glass ionomer cement. Caries status was recorded using DMFT index (WHO 1997) and revaluated after 6 months using DMFS index (WHO 1979). Saliva was collected for microbiological assessment of SM count on four occasions, baseline, 1 week, 1 month, and 6 months after ART approach. The results of the microbiological tests were statistically analyzed using the non-parametric Mann-Whitney rank test.

Results:

The results showed a significant reduction of SM levels in saliva immediately 1 week following the ART approach with mean SM counts of 1.5763 (10⁶ CFU/ml) and 1.1286 (10⁵ CFU/ml) pre- and 1 week post–ART, respectively. Reduction in the SM count was seen in 89.47% of children after 1 week of ART treatment. The mean SM count after 1 month and 6 months post-ART was 1.4814 (10⁶ CFU/ml) and 1.4722(10⁶ CFU/ml), respectively.

Conclusion:

It was concluded from the results that the ART technique was successful in reducing the SM counts in saliva significantly for a period of 1 week post treatment. Although the mean SM counts remained less than the baseline after 6 month evaluation, a trend toward re-establishment of SM to the baseline count was noticed.

Caries prevalence associated with Streptococcus mutans and Streptococcus sobrinus in Japanese schoolchildren

BACKGROUND

Streptococcus mutans and Streptococcus sobrinus are known to be associated with dental caries in humans.

AIM

We used a polymerase chain reaction method to detect S. mutans and S. sobrinus in 128 Japanese schoolchildren and then compared their presence with the dental caries experience.

DESIGN

Plaque samples were collected from all erupted tooth sites with a sterile toothbrush, and dental examinations were performed to determine the numbers of decayed and filled teeth in primary (dft) and permanent (DFT) dentition using the WHO caries diagnostic criteria. Fisher's PLSD test was employed to compare caries scores between combinations of the detected bacteria.

RESULTS

Streptococcus mutans and S. sobrinus were present in 38.3% and 68.0%, respectively, whereas 14.8% were positive for S. mutans alone, 44.5% for S. sobrinus alone, and 23.5% for both S. mutans and S. sobrinus, with 17.2% negative for both. The DFT, dft, and total (DFT + dft) scores for subjects positive for both S. mutans and S. sobrinus were significantly higher than those positive for S. mutans alone (P < 0.05, in triplicate).

CONCLUSION

These results suggest that schoolchildren harbouring both S. mutans and S. sobrinus have a significant higher dental caries experience in both permanent and primary teeth as compared to those with S. mutans alone.

Studies on strains of Streptococcus mutans isolated from caries-active and caries-free individuals in Iceland

Background

Dental caries has been strongly associated with mutans streptococci, particularly Streptococcus mutans and S. sobrinus. Many studies have linked these organisms to the carious process and counts of mutans streptococci have been used to monitor caries risk. The high levels of caries generally found in Iceland have enabled several studies to be performed on the variation within strains of S. mutans.

Methods

This paper reports some studies showing phenotypic differences between strains of S. mutans that were related to whether the strain was isolated from an individual with active caries or from a caries-free subject.

Results

Strains from individuals with active caries generally adhered better to apatite, were more vigorous in decalcifying apatite and had bacteriocin-like activity that was likely to help the strain compete successfully with other strains, for example in the dental plaque biofilm.

Conclusions

Phenotypic differences exist between strains of S. mutans depending on the caries activity of the individual from whom the strain was isolated.

Clinically acceptable restorations may be a hotbed for cariogenic microbes

OBJECTIVE

The aim of this study was to investigate the cross-sectional association of dental restorations with salivary cariogenic pathogens among the elderly to establish effective parameters of caries risk for this population.

MATERIALS AND METHODS

Stimulated whole saliva was collected from 289 community-dwelling older adults (66.2 ± 3.9 years old) who had 20 or more teeth. Salivary levels of three cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and lactobacilli) were estimated using quantitative polymerase chain reaction (real-time PCR) method.

RESULTS

The mean number of residual teeth was 26.4, and restored teeth with crowns, inlays and composite resin were 7.35, 3.88 and 0.68, respectively. The number of crowns correlated positively with salivary S. mutans, S. sobrinus and lactobacilli. Multiple linear regression analyses showed that the number of restored teeth with crowns was independently associated with salivary S. mutans, S. sobrinus and lactobacilli after controlling for age, gender, number of residual teeth and salivary flow rate. Salivary flow rate was independently associated with salivary S. mutans and lactobacilli.

CONCLUSION

The number of crowns had an association with salivary levels of cariogenic bacteria, suggesting that this parameter may be a caries risk indicator for the elderly population.

Inhibitory Effects of Partially Decomposed Alginate on Production of Glucan and Organic Acid by Streptococcus sobrinus 6715

Our previous study has already clarified that partially decomposed alginate (Alg53) by Vibrio alginolyticus SUN53 has a competitive inhibitory effect on sucrase. The objective of this study is to evaluate the influence of Alg53 on the production of glucan from sucrose by glucosyltransferase and acid from glucose by Streptococcus sobrinus 6715. Glucosyltransferase was prepared from cultural medium of S. sobrinus using ultrafiltration and hydroxyapatite chromatography. In order to examine the inhibitory effect of Alg53 for production of glucan by GTase, partially purified GTase, sucrose and Alg53 solution were incubated at 37°C. The influence of Alg53 on the production of acid from glucose was evaluated by a degree of pH decline during the incubation for 60 min. The original Alg53 solution markedly inhibited to 21% of the synthesis of water-insoluble glucan from sucrose and that of 10-fold diluted of Alg53 solution was 23%. However, the production of water-soluble glucan from sucrose by GTase was hardly affected by Alg53. Furthermore, Alg53 suppressed dose-dependently pH decline by organic acid converted from glucose. These results suggest that Alg53 is expected as a functional food material which prevents or reduces dental caries.

Ecology of lactobacilli in the oral cavity: a review of literature

Lactobacilli appear in the oral cavity during the first years of a child's life. Their presence depends on numerous factors such as the presence of ecological niches e.g. natural anfractuosities of the teeth.A strong correlation has been established between the saliva Lactobacillus count and dental caries, the higher the DMF index, the higher the number of children harbouring a high Lactobacillus count.Among children, the presence of lactobacilli in coronal caries is incontestable. Among adults, lactobacilli are found in root caries. Since 1999, taxonomical revisions make it difficult to interpret the results obtained in the numerous previous studies carried out on the identification of oral lactobacilli, but whatever the sampling method or the identification technique, the carious site or the age of sampled subjects, most species belong to the Lactobacillus casei group.This is important because if a specific correlation can be found between few species of lactobacilli and caries a better understanding of their properties could allow the development of new tools for prevention.

Effect of mixed mutans streptococci colonization on caries development

OBJECTIVE

To evaluate the clinical importance of mixed mutans streptococci colonization in predicting caries in preschool children.

METHODS

Caries prevalence was examined twice, with a 6-month interval, in 410 preschool children aged 3-4 years at baseline. A commercial strip method was used to evaluate the mutans streptococci score in plaque collected from eight selected interdental spaces and in saliva. Mutans streptococci typing polymerase chain reaction (PCR) assays (Streptococcus sobrinus and Streptococcus mutans, including serotypes c, e, and f) were performed using colonies on the strips as template.

RESULTS

Twenty variables were examined in a univariate analysis to predict caries development: questionnaire variables, results of clinical examination, mutans streptococci scores, and PCR detection of S. sobrinus and S. mutans (including serotypes c, e, and f). Sixteen variables showed statistically significant associations (P < 0.04) in the univariate analysis. However, when entered into a logistic regression, only five variables remained significant (P < 0.05): caries experience at baseline; mixed colonization of S. sobrinus and S. mutans including S. mutans serotypes; high plaque mutans streptococci score; habitual use of sweet drinks; and nonuse of fluoride toothpaste.

CONCLUSION

'Mixed mutans streptococci colonization' is a novel measure correlated with caries development in their primary dentition.

Influence of a Fluoride Mouthrinse on Mutans Streptococci in Schoolchildren

This study aimed to determine whether the long-term use of a fluoride mouthrinse affects the salivary levels of mutans streptococci. Two hundred and fifteen schoolchildren (aged 9-10 years) participated. One hundred and forty-nine of these children had used a fluoride mouthrinse since 5 years of age at nursery school, and the remaining 66 children had not. DFT (decayed and filled teeth) was recorded, and the salivary levels of Streptococcus mutans and Streptococcus sobrinus were measured using mitis salivarius bacitracin agar. The group that had used a fluoride mouthrinse had a significantly lower prevalence of both S. mutans and S. sobrinus (p = 0.038) and a significantly lower DFT score (p < 0.001) than the other group. Using logistic regression analysis including caries experience at baseline as a dependent variable, the odds ratio of carrying S. mutans alone was 8.0 (p = 0.066) and that of carrying both S. mutans and S. sobrinus was 16.5 (p = 0.022) in the group that had not used the fluoride mouthrinse. Children carrying both S. mutans and S. sobrinus had a higher caries incidence in 1 year than the others, with odds ratios of 5.73 (p = 0.067) in the group with a fluoride mouthrinse and 3.47 (p = 0.035) in the group without it. These results show that the long-term use of a fluoride mouthrinse is associated with reduced salivary levels of mutans streptococci and this bacterial reduction may partly contribute to the suppression of dental caries in children using a long-term fluoride mouthrinse.

Differentiation of Streptococcus mutans and Streptococcus sobrinus via genotypic and phenotypic profiles from three different populations

Routine identification of Streptococcus mutans and Streptococcus sobrinus is generally based upon growth on various selective media, colony morphology and biochemical characteristics. We examined various approaches of differentiating these two species through a combination of the conventional phenotypic methodology with chromosomal DNA fingerprint (CDF) and arbitrarily primed polymerase chain reaction (AP-PCR) methods. Initially, ten ATCC type strains and 20 randomly selected clinical isolates of mutans streptococci (MS) were characterized and grouped into two major types based on patterns generated by the CDF using HaeIII digestion. The CDF's patterns with restriction fragments equal to or greater than 6.6 kb were defined as the CDF-1 group. The CDF's patterns with restriction fragments less than 6.6 kb were defined as the CDF-2 group. Both groups were then examined for biotype, serotype, and composition of DNA via thermal denaturation. AP-PCR was applied and evaluated for the capability of delineating S. mutans from S. sobrinus strains. Results of this study showed that all CDF-1 strains fit within a G+C range of 36.2% to 42.2%, whereas the CDF-2 strains had a G+C range of 45.8% to 47.0%. The serotyping assay exhibited 100% sensitivity, 90% specificity and 86.7% agreement with the CDF. The biotyping assay presented the poorest specificity (38.5%), indicating the highest variability. The capability of AP-PCR in differentiation of S. mutans from S. sobrinus was comparable to the CDF method, suggesting that either of these two approaches can and may serve as a viable alternative method to serotyping or biotyping of MS.

Effect of 3-hydroxymethylene-2-thioxopyrrolidine on growth of two species of mutans streptococci and their in vitro plaque formation

3-Hydroxymethylene-2-thioxopyrrolidine (HMTP), the major product derived from radish mustard oil, was studied for its activity to inhibit the growth of mutans streptococci, their in vitro plaque formation and their glucan production. The minimum inhibitory concentration (MIC) (800-1600 mg/l) of HMTP at pH 7.0 was reduced to 200 mg/l by lowering the medium pH to 5.0. A dose-dependent inhibition of in vitro plaque formation was observed at 200-800 mg/l dose of HMTP. Production of water-insoluble glucan (WIG) was effectively inhibited by 45-98%, depending on HMTP dose (200-800 mg/l), while only 22% inhibition of water-soluble glucan (WSG) production was observed at an 800 mg/l dose.

Biological mechanisms of early childhood caries

The present paper reviews biological issues in early childhood caries (ECC) in light of the current understanding of the field. Despite the general global decline in dental caries in the past decades, ECC has become a significant problem in many developing countries and some minority communities in western industrialized nations. Like other types of caries, ECC is caused by mutans streptococci that ferment dietary carbohydrates to produce acid attacks on susceptible teeth over a period of time. However, while the general etiology of ECC appears similar to that of other types of caries, the predisposing factors are still unclear. The biology of ECC may be modified by several factors unique to young children, related to the implantation of cariogenic bacteria, immaturity of the host defense systems, as well as behavioral patterns associated with feeding and oral hygiene in early childhood.

Rapid isolation of chromosomal DNA from oral streptococci and polymerase chain reaction-oriented restriction fragment-length polymorphism analysis for genetic heterogeneity

We have extensively modified the published method for the lysis of gram-positive bacteria to isolate chromosomal DNA from only 1 ml of oral streptococcal overnight culture. Cells were incubated with lysozyme and R Nase A in the presence of polyethylene glycol. After centrifugation, cells were lysed with sodium dodecyl sulfate and proteinase K. Following ethanol precipitation, sodium dodecyl sulfate solution was added to the residue, and the pellet was completely dispersed by incubating at 65 degrees C. The chromosome was purified by extraction over phenol and chloroform. Two regions corresponding to the ribosomal RNA (rrn) operon and the glucosyltransferase gene were amplified using the chromosome from Streptococcus mutans and Streptococcus sobrinus by polymerase chain reaction (PCR). Genetic heterogeneity was assessed by restriction fragment-length polymorphism (PCR-RFLP). The PCR-RFLP analysis readily allowed us to subtype each strain, suggesting that the strategy presented here will provide a useful tool to verify epidemiological studies at the molecular level.

Trends in dental health among Icelandic urban children

Caries experience, oral hygiene and caries-related salivary parameters were recorded in a 20% representative sample of 12-year-old schoolchildren in Reykjavik, Iceland in 1991. The majority of the children was re-examined 3 years later in 1994. Trends in prevalence of caries and salivary bacteria were assessed by comparison with an analogous earlier longitudinal study (1984-87). Mean DFS values for 12-year-olds were 12.1 and 4.1, for 15-year-olds 23.3 and 11.3 in the earlier and later study, respectively. Reduction in DFS was 66% and 52% for the respective age groups. The decline was most pronounced in the group with low caries prevalence. Trends in caries experience were paralleled by salivary bacteria. The mean caries scores and frequency distributions of 15-year-olds in 1994 closely resembled those of 12-year-olds a decade earlier, suggesting a delay rather than a true fall in caries prevalence.

The plaque acidogenic response to carbohydrates of children from three ethnic groups in South Africa

The plaque acidogenic response of children from three ethnic groups in South Africa to four different carbohydrates was investigated using the plaque sampling method. A total of 30, 12-year-old children, ten black, ten 'coloured' and ten white, completed this study. The foods tested were 10 per cent sucrose solution, maize porridge, strawberry flavoured yoghurt and banana. The blacks produced an intermediate plaque pH response to sucrose compared with the 'coloureds' and whites but the smallest response for the other carbohydrate challenges. It was concluded that a difference exists in the plaque acidogenic response to carbohydrate between the three ethnic groups and that this may in part account for differences in caries prevalences.

Restoring oral health. On the rise and fall of dental caries in Iceland

During the last decade, a continuous decrease in dental caries has been observed among schoolchildren in Iceland. In this paper, various epidemiological studies have been reviewed and summarized to illustrate caries prevalence, and how it has changed during the last decades. Furthermore, an attempt has been made to describe some of the factors involved and their possible effects on caries disease. During this period, sugar consumption increased, especially in the form of sweets and soft drinks. At the same time, the import of toothpaste increased, and preventive measures such as fissure sealants and fluoride rinsing programs were intensified. Other factors likely to have had an impact were changes in treatment philosophy and increased personnel resources. There does not seem to be any single factor responsible for the onset of the caries decline. It rather looks as if this was a multifactorial effect due to a number of different preventive measures. During recent years, a change in treatment philosophy, the evident increase in fluoride toothpaste consumption, and possible changes in the oral microbial flora, together with the use of fluoride varnishes, sealants, and increased manpower, may explain the decline.

Associations between dietary intake, dental caries experience and salivary bacterial levels in 12-year-old English schoolchildren

A population of 328 12-yr-old English schoolchildren, consuming their normal diets, was investigated in a cross-sectional study to determine the interactions between caries experience, oral hygiene status as gingival index (GI), dietary intake (as number of eating events per day and the number of eating events per day at which sugar-containing foodstuffs, confectionery or starch-containing foods were consumed) and salivary levels of caries-associated micro-organisms (mutants streptococci, lactobacilli and yeasts). The mean (+/- SD) decayed, missing and filled surfaces (DMFS) (excluding precavitation lesions) score was 3.05 +/- 3.85 and 5.72 +/- 5.00 (including precavitation lesions). The DMFS scores were significantly related to the salivary levels of caries-associated micro-organisms and to the number of eating events per day for total number of eating events and the number of eating events at which sugar-containing foods or confectionery were consumed. These associations were apparent in both bivariate and partial correlation coefficients with the caries-associated micro-organisms and GI controlled. The total daily intakes of food types, except for starch, were not associated with caries experience. No significant correlations were found between intake of food types and salivary levels of caries-associated micro-organisms except that the mean number of confectionery-eating events was correlated with lactobacillus levels (r = 0.136, p < 0.01). The salivary levels of mutans streptococci, lactobacilli and yeasts were significantly correlated with GI scores. These data do not indicate simple associations between dietary intake, caries and levels of caries-associated micro-organisms. Poor oral hygiene, in children consuming unrestricted diets, may influence the salivary levels of mutans streptococci, lactobacilli and yeasts irrespective of the frequency or amount of sugar consumed. Multiple regression analyses revealed that three variables--GI (probably an indicator of toothbrushing behaviour with a fluoride-containing toothpaste), salivary concentration of lactobacilli and frequency of ingestion of confectionery/sugary foods--were independently and positively related to caries experience.

Use of a novel mobilizable vector to inactivate the scrA gene of Streptococcus sobrinus by allelic replacement

The virulence factors of the cariogenic bacterium Streptococcus sobrinus have been difficult to assess because of a lack of tools for the genetic manipulation of this organism. The construction of an Escherichia coli-Streptococcus shuttle vector, pDL289, that can be mobilized into S. sobrinus by the conjugative plasmid pAM beta 1 was described in a previous report. The vector contains pVA380-1 for replication and mobilization in streptococci, the pSC101 replicon for maintenance in E. coli, a kanamycin resistance marker that functions in both hosts, and the multiple cloning site and lacZ from pGEM7Zf(-). pDL289 is stable with or without selection in several species of Streptococcus. In this study, a derivative with a deletion in the minus origin of the pVA380-1 component of pDL289 was constructed. This derivative, pDL289 delta 202, was less stable than pDL289 in Streptococcus gordonii Challis, Streptococcus mutans, and S. sobrinus. Both pDL289 and pDL289 delta 202 were mobilizable by pAM beta 1 into S. sobrinus, with frequencies of 3 x 10(-6) and 1 x 10(-7) transconjugants per recipient CFU, respectively. The cloned scrA gene of S. sobrinus 6715-10 coding for the EIISuc of the sucrose-specific phosphoenolpyruvate phosphotransferase system was interrupted by the insertion of a streptococcal spectinomycin resistance gene active in E. coli and streptococci. The interrupted scrA gene was subcloned into both pDL289 and pDL289 delta 202. Each recombinant plasmid was introduced into the DL1 strain of S. gordonii Challis, which was then used as a recipient for the conjugative transfer of pAM beta 1. The latter plasmid was used to mobilize each recombinant plasmid from S. gordonii Challis DL1 to S. sobrinus 6715-10RF. Subsequently, recombinants derived from a double-crossover event were isolated on the basis of resistance to spectinomycin and susceptibility to kanamycin. Recombinational events were confirmed by Southern hybridization, and the inactivation of the EII Suc in double crossovers was confirmed by phosphotransferase system assays. This is the first report of allelic replacement in S. sobrinus.

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

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 < 10(5) compared with 13.8% in the study 1984. The mean caries prevalence in the permanent dentition (DFStot) was 11.0, which is significantly lower than in 1984 (mean DFStot 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.

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%).

Caries incidence, effect of preventive measures, and caries prediction in Uruguayan children

In 1988, 100 12- to 13-year-old children from two neighborhoods in Montevideo with different standards of living were examined. Twenty-three children with large numbers of mutans streptococci, lactobacilli, or decayed surfaces or a combination of these factors were considered to be at high risk of developing caries. Twelve of these 23 children were selected for special preventive measures. A second examination was made 18 months later, at which 81 of the originally 100 children were studied. The clinical and microbiologic variables were tested for their ability to predict caries by calculating their sensitivity, specificity, the positive and negative predictive values. The incidence of new DMFS was significantly higher in the children from the low than in those from the high socioeconomic area. It was also significantly higher in the children considered being at high risk than in those at low risk at the start of the study. Preventive measures reduced the caries risk. The highest sensitivity was obtained with the clinical test, whereas the highest specificity was obtained with the combined clinical and microbiologic tests. The findings indicate that methods for identifying children at risk which started to be used in Scandinavia 20 years ago could be applied in the Uruguayan population of today. It is valuable to know this, as the resources for both treatment and prevention are very limited.

Longitudinal study of caries, cariogenic bacteria and diet in children just before and after starting school

Fifty 5-yr-old preschool children living in Akranes, a small community in West Iceland known to have a high caries prevalence, were investigated with respect to caries, salivary counts of mutans streptococci and lactobacilli, and consumption of cariogenic foods. Fifteen months later, after being in school for half a year, 43 of the 50 children were reexamined and investigated as before. Mean dmfs scores rose from 7.1 to 9.0, but the scores including initial caries rose from 9.7 to 15.3. Mutans streptococci were carried by 84% of children on both occasions with a mean count 2.1 and 3.6 x 10(5) cfu/ml. Lactobacillus carriage increased from 29 to 38% and the mean count from 5.1 to 13 x 10(3) cfu/ml at 6 yr. The frequency of consumption of sugar-containing foods increased from 4.2 to 5.2 intakes per day and between-meal snacks rose from 3.0 to 3.7 per day. Children classified as "misusing" sugar were 59% at 5 yr and 83% at 6 yr. The mean caries score at 6 yr for children "misusing" sugar was 10.7 but only 2.0 for those not misusing sugar. Thus the deterioration in dental health appears, in these children, to be associated with the increased consumption of sweets and other cariogenic between-meal snacks after starting school.

Salivary lactobacilli explain dental caries better than salivary mutants streptococci in 4-5-year-old children

The present comparative study was undertaken to determine which of the bacteria, lactobacilli (lbc) and mutans streptococci (ms), in saliva better explains the variation of caries in 2728 South African 4-5-yr-old children. Caries was diagnosed according to WHO criteria. For lbc, the Dentocult system was used. The number of ms in stimulated saliva was counted on MSB agar plates. For correction of confounding factors, data on the frequency of intake of sweets were derived from extensive interviews. Oral hygiene was determined according to the simplified debris index of Greene & Vermillion. Simple correlation analyses between dmfs and bacterial counts were done for the total material and for three caries intervals by calculating Spearman's and Pearson's coefficients of correlation. Multivariate regression analyses were done on all intervals to correct for the confounding effects of regular intake of sweets, presence of salivary ms or lbc, and oral hygiene. Of the children, 68% had detectable lbc in the saliva, and 74% had ms. Except for children with more than 6 dmfs, the explanatory values, i.e., percentage of variation in dmfs explained, were higher for the lbc than for ms. Before correction, the values for the total material were 15 vs 6%; for children with caries, 7 vs 5%; for those with 1-6 dmfs, 5 vs 0.4%; and for those with more than 6 dmfs, 0.3 vs 2%. All r-values were reduced after correction, indicating that the confounders explain some of the correlation between dmfs and bacterial count.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental caries and microbial and salivary conditions in Uruguayan children from two different socioeconomic areas

Dental caries, microbial and salivary conditions, dietary habits, and socioeconomic conditions were studied in 100 12- to 13-year-old children from 2 different socioeconomic areas in Montevideo: Pocitos and Piedras Blancas. The residents of Pocitos had a higher educational level, better housing conditions, and occupations involving higher earnings than those of Piedras Blancas. The caries prevalence in the two areas was about the same, but the children in Piedras Blancas had more decayed surfaces and fewer filled surfaces than the children in Pocitos. The mean values for caries in Piedras Blancas and Pocitos were, DMFT, 4.2 and 4.2; DMFS, 8.1 and 7.8; DS, 4.7 and 2.5; and FS, 1.7 and 4.7, respectively. The differences in DS and FS were statistically significant. The frequency of sugar intake and the salivary secretion rate were similar, but the buffer capacity was significantly higher in Pocitos than in Piedras Blancas. The plaque index was the same, but the distribution of cariogenic microorganisms differed significantly. Fifty-eight per cent of the children in Piedras Blancas had more than 10(6) CFU of mutans streptococci per milliliter saliva, compared with 17% of the children in Pocitos. Similar differences were found with regard to the lactobacilli. The percentage of children with high numbers of mutans streptococci was higher in Piedras Blancas and lower in Pocitos than in previous epidemiologic studies in Scandinavia. It was, however, higher than that recently noted in Finland.

Isolation frequency and serotype distribution of mutans streptococci and Actinobacillus actinomycetemcomitans, and clinical periodontal status in Finnish and Vietnamese children

The isolation frequency and serotype distribution of mutans streptococci and A. actinomycetemcomitans (A.a.) were investigated in a group of Finnish (n = 16) and Vietnamese (n = 16) children, matched by sex, age, and caries status. In the Vietnamese children, the isolation frequencies were higher than in the Finnish children: 100%/62% for mutans streptococci and 78%/13% for A.a. Isolates (n = 3-8) from plaque and saliva were serotyped by immunodiffusion technique using serotype-specific antisera against serotypes c, e, f, d, and g for mutans streptococci and a, b, c, d, and e for A.a. The distribution of mutans streptococci serotypes in Finnish/Vietnamese children was: c 100%/50%; e 10%/31%; d 0%/56%; g 20%/38%. The frequency of plural serotypes was 30%/75%, respectively. In the Vietnamese group the serotype distribution of A.a. was: a 36%, b 27%, and c 63%; 45% of children carried two serotypes. One Finnish child harbored serotype a and one serotype b. The mean percentage of bleeding gingival sites was 7.4 in the Finnish and 15.1 in the Vietnamese group. Calculus and clinically deepened gingival pockets were more frequent findings in the Vietnamese children. The results indicate considerable differences in bacteriologic status and in clinical periodontal status between these Finnish and Vietnamese children.

Intra- and inter-individual variation in salivary flow rate, buffer effect, lactobacilli, and mutans streptococci among 11- to 12-year-old schoolchildren

Both intra- and inter-individual variation in salivary flow rate, buffer effect, and the levels of salivary mutans streptococci and lactobacilli were analyzed in 128 11-year-old children. The follow-up period was 9 months, with six saliva samplings done at regular intervals. Inter-individual variation was relatively large in paraffin-stimulated salivary flow rate: low (< 1.0 ml/min) and high (> or = 2.0 ml/min) flow rates were measured in 18% and 13% of the children, respectively. Intraindividual variation during the follow-up period was found in 63% of the boys and in 73% of the girls. The buffer effect stayed stable in all samplings in 59% of the boys and in 42% of the girls. Buffer effect was significantly (p < 0.001) lower in girls than in boys. Mutans streptococci were analyzed by a chair-side method (Strip mutans test) and by cultivation on mitis-salivarius-bacitracin (MSB) agar plates. The results of the two methods correlated highly significantly (r = 0.79, p < 0.001). With the Strip mutans test no variation in test scores occurred in 49% of all subjects in all six samplings, whereas the respective percentage for MSB scores was only 19%. No variation in salivary lactobacilli occurred in only 18% of the subjects, and in 13% the intraindividual variation was as high as > or = 3 logs. These results show that in young teenagers with a developing dentition, simultaneous changes in behavioral, hormonal, and dietary factors make single-point measurements of salivary factors too unreliable for caries-diagnostic or predictive purposes.

Dental caries and Streptococcus mutans in a rural child population in Iceland

In spite of having a high socioeconomic standing, in Iceland caries prevalence has remained stubbornly high. This study reports findings from a mixed fishing and farming community in East Iceland that has traditionally been associated with the highest prevalence of caries. A total of 188 children aged 3-16 yr (96.4% of residents of that age group) were examined. At 6 yr the mean dmfs score was 4.1, DMFS 0 and 48% were caries-free. The mean DMFS score at 12 yr was 4.7 and 22.6% remained caries-free but at 16 yr the DMFS score was 11.6 and no children were caries-free. Caries was unevenly distributed within each age group and was more prevalent among residents of the fishing town than the surrounding farming district. In a pilot study conducted in 1989 mean counts of Streptococcus mutans for children aged 4-7 yr were 2.6 x 10(5) cfu/ml and declined to 4.6 x 10(4) cfu/ml in 1990 after a program of chlorhexidine brushing had been added to the routine caries preventive measures adopted in this community. It may therefore be possible to screen Icelandic children for caries risk and apply preventive measures to those demonstrated to be most in need.

Effects of Weight Watchers' diet on salivary secretion rate, buffer effect and numbers of mutans streptococci and lactobacilli

The aim of this investigation was to study how a change to the dietary regimen of the Weight Watchers' (WW) affected salivary secretion rate, buffer effect and number of cariogenic bacteria. Thirty-three women joining the WW were saliva sampled at the evening prior the day of the start of the dietary regimen and after 4 and 8 wk on the dietary regimen. No significant changes were found regarding saliva secretion rate and buffer effect. A significant decrease of salivary numbers of mutans streptococci and lactobacilli occurred. Between the 4th and 8th wk of dietary regimen an increase of cariogenic bacteria occurred but not back to the baseline values. At baseline 15 of the WW carried Streptococcus sobrinus in addition to Streptococcus mutans. The total number of salivary mutans streptococci and lactobacilli was significantly higher in those subjects. In conclusion the dietary regimen of the WW, based on food choice and distributions of meals in agreement with a non-cariogenic diet, reduced the number of cariogenic bacteria in most subjects, but not in all, while the secretion rate and buffer effect remained the same.

Salivary levels of mutans streptococci and lactobacilli in dentate 80- and 85-year-old Swedish men and women

The number of Streptococcus mutans, Streptococcus sobrinus, and lactobacilli in whole stimulated saliva was examined in 130 dentate 80- and 85-yr-old persons. 88.5% were positive for mutans streptococci and 29% carried greater than 10(6) cfu per ml saliva. S. mutans was most frequently isolated and was found in 114 persons (88%) alone or in combination with S. sobrinus. S. sobrinus was detected in 33 persons (25%), who also showed significantly higher salivary numbers of both mutans streptococci and lactobacilli than persons from whom S. sobrinus was not isolated. The S. sobrinus carriers also had significantly lower stimulated saliva secretion rates than the non-carriers. 95% of the subjects had detectable levels of lactobacilli in saliva with 35% having greater than 10(5) cfu per ml saliva. When the subjects were divided into classes according to the number of intermaxillary contacts, i.e. the Eichner classification, the distribution of subjects with high and low salivary counts of cariogenic bacteria varied. Thus fewer subjects belonging to Eichner class A showed higher salivary numbers of mutans streptococci (14% had greater than 10(6) cfu/ml) as well as lactobacilli (21% had greater than 10(5) cfu/ml) than, for example, subjects belonging to Eichner class B (26% had greater than 10(6) cfu/ml of mutans streptococci, 35% had greater than 10(5) cfu/ml of lactobacilli). Subjects who carried a removable denture(s) had significantly higher salivary numbers of both mutans streptococci and lactobacilli than subjects without removable dentures.

University of North Carolina caries risk assessment study. III. Multiple factors in caries prevalence

The baseline caries experienced of approximately 5,000 children in South Carolina and Maine was used as the dependent variable in caries risk assessment analyses. Clinical, microbiologic, and demographic factors served as independent variables in a multivariate relationship to caries through regression and discriminant function analyses. Four factors--number of dental visits by the child in the past year, presence of white spot lesions, and both the urgency of need for restorative care and the future caries increment predicted by the examiner--associated significantly and consistently with caries prevalence in primary and permanent teeth of first and fifth graders at both study sites. Several factors associated significantly with caries prevalence at only one site or grade within a site, suggesting that wide applicability of a specific caries risk assessment model may be limited. In these analyses, sensitivity ranged from .60 to .72 and specificity varied from .86 to .91 in the four grade-site groups. The ultimate goal of this longitudinal study is to identify highly caries-prone children in time to prevent the occurrence of a future caries increment. Although the lack of consistent association of many variables, including microbiologic factors, with baseline caries prevalence was unexpected, it is expected that some of these variables will contribute predictive power in the prospective study.

Dental caries and salivary and microbial conditions in 50-60-year-old persons

In a group of 124 persons, 50-60 yr old, the prevalence at baseline of mutans streptococci (MS) and lactobacilli and the salivary secretion rate and buffer capacity were examined. The mean secretion rate was 1.58 mL/min with a flow rate below 1 mL/min found in 20% of the persons. A buffer capacity below end pH 5.5 was observed in 64% of the subjects. MS was not detected in 5% of the persons whereas 17% had 10(6) or more MS per ml saliva. Lactobacilli were not found in 10% of the persons while 21% had counts in excess of 10(5) CFU mL. A new examination 5 yr later in 1986 revealed no significant changes in secretion rate and buffer capacity or in the population of lactobacilli, whereas markedly elevated levels of salivary MS were found. S. sobrinus was detected in 35-37% of the persons at the two examinations. Persons with both S. mutans and S. sobrinus had more MS than persons with only S. mutans.

Correlation between child caries incidence and S. mutans/lactobacilli in saliva after correction for confounding factors

The correlation between caries incidence and Streptococcus mutans/lactobacilli in saliva was studied in two different age groups, followed from ages 5 to 7 and from 12 to 14. The coefficients of correlation were computed before and after correction for the confounding effect of oral hygiene and the alternative bacteria. The best value for S. mutans was found for the total material in the younger age group (r = 0.24). For lactobacilli the best value was found for the total materials and in the subgroup with less favorable oral hygiene and S. mutans count in the older age group (r = 0.18). The connection between caries incidence and these bacteria was shown to be weak at the individual level, particularly after correction for confounding. The caries differences at group level between subgroups with less favorable and favorable counts of the bacteria were also checked after correction for confounders. The "reduction" figures for S. mutans varied between 23 and 63% and for lactobacilli between 8 and 37% in the two sets of material.

Associations between salivary levels of Streptococcus mutans, Streptococcus sobrinus, lactobacilli, and caries experience in Kenyan adolescents

Salivary levels of mutans streptococci (S. mutans and S. sobrinus) and lactobacilli were determined in a random sample of rural Kenyans between 15 and 19 years of age (n = 149). It is possible for the natural history of dental caries in this population to be studied since it is characterized by a limited access to conventional dental treatment. Using a short set of biochemical tests, we identified from seven to ten presumptive mutans streptococcus colonies--cultured from the saliva of each individual--to differentiate between S. mutans and S. sobrinus. No colonies resembling S. rattus (S. mutans serotype b) were isolated. Lactobacilli were identified as Gram-positive, catalase-negative rods. The mean D1-4MFS and D3-4MFS were 7.03 +/- 6.43 and 1.46 +/- 3.44, respectively. The mean mutans streptococcus and lactobacillus levels were 8.7 x 10(4) and 6.7 x 10(4), respectively. The salivary mutans streptococcus and lactobacillus levels were significantly correlated (p less than 0.01). Of the subjects, 64% harbored only S. mutans, 4% only S. sobrinus, 30% both species, and 2% neither. Lactobacilli were ubiquitous. The caries experience of the group was significantly (p less than 0.001) correlated with both the total salivary level of mutans streptococci and the salivary S. mutans levels, but not with the salivary S. sobrinus level.