Distribution and prevalence of mutans streptococci in the human dentition

The prevalence of mutans streptococci was determined in 14,859 samples of plaque from all available tooth surfaces in 114 subjects. The clinical examination included location of incipient caries lesions, fillings, and crowns. Mutans streptococci were detected on 40% of all tooth surfaces. The frequency distribution of mutans streptococci and the level of colonization showed a decreasing gradient from molars to incisors for buccal, lingual, occlusal, and approximal surfaces. The location and number of approximal restorations were closely related to the colonization level of mutans streptococci except for second and third molars. Restored surfaces tended to be more colonized by mutans streptococci than sound surfaces, except for occlusal surfaces. A high prevalence of mutans streptococci was found in plaque samples from tooth-colored fillings, especially on buccal and lingual surfaces.     

The toothpick method in relation to other plaque sampling techniques for evaluating mutans streptococci

The aim of the present study was to compare the use of toothpicks with other sampling methods for determination of mutans streptococci on different tooth surfaces. In nine persons with > 10⁵ CPU per ml saliva of mutans streptococci, plaque samples were taken from 90 buccal and lingual surfaces. 108 occlusal surfaces and 90 approximal surfaces with toothpicks. The prevalence of mutans streptococci on these tooth surfaces was compared with samples taken at four 1-week intervals on the same tooth surfaces with a carver (buccal/lingual surfaces), a needle (occlusal surfaces) or a dental floss (approximal surfaces). Each sample was plated on MSB agar and the presence of mutans streptococci was expressed on a scale varying from 0 to 4. On two of the sampling occasions the amount of plaque, mirrored by total viable counts on blood agar, was also determined. Only for buccal/lingual plaque samples was a difference in total counts between methods noted and then with higher total recoveries obtained after sampling with toothpicks. More surfaces were found to be positive for mutans streptococci when samples were taken with a toothpick than with a carver, needle or floss. On surfaces positive for mutans streptococci the colonization score was higher in samples taken with a toothpick than with a carver or a needle while samples taken with a floss showed a tendency to higher levels of mutans streptococci than samples collected with a toothpick. The data indicate that the results obtained by using toothpicks for evaluating the prevalence of mutans streptococci an individual tooth surfaces compare favorably with the other methods tested     

Crevicular IgG antibodies and Streptococcus mutans on erupting human first permanent molars.

The specific IgG antibody activity against indigenous Streptococcus mutans in gingival crevicular fluid (GCF) was determined in 25, 6-7-yr-old children. Samples of plaque and GCF were collected from all erupting first permanent molars. Plaque samples were also collected from the adjacent second primary molars. The presence of clinical caries was scored as defs. In the same individual a highly significant correlation (p less than 0.005) was found between the level of specific antibody activity in GCF when comparing first permanent molars with each other. No correlation was found between the specific antibody activity in GCF and the number of indigenous Strep. mutans colonizing the buccal surfaces of the first permanent molars. Caries-free children had significantly less specific antibody activity in GCF than children with caries experience (p less than 0.05). In the same child a highly significant correlation (p less than 0.0001) was found between the level of colonization by mutans streptococci on the permanent molars and the adjacent second primary molars.     

Dental location of Streptococcus mutans and Streptococcus sobrinus in humans harboring both species

The distribution and prevalence of Streptococcus mutans and Streptococcus sobrinus were determined in plaque samples from the cervical areas of all buccal, lingual and approximal tooth surfaces and from the fissures of all occlusal sites in 40 subjects harboring both species. S. mutans was detected more often and in higher numbers than S. sobrinus. There were more teeth detected with S. mutans only than with S. sobrinus only. Most teeth harbored both of these mutans streptococci species, indicating a positive association. The highest numbers of CFU for both species were detected on the molars, with the lowest incidence on the anterior teeth. The presence of S. mutans was relatively similar on all teeth tested, while the presence of S. sobrinus was relatively higher on the molars compared to the anterior teeth. S. mutans and S. sobrinus were found to colonize the buccal surfaces in almost equal numbers. On all other surfaces, S. mutans was detected more frequently or in higher numbers compared to S. sobrinus. No significant differences could be found in the relative proportions of S. mutans and S. sobrinus between sound, decayed or filled tooth surfaces.     

Mutans streptococci and lactobacilli in saliva after the application of fissure sealants

Because dental fissures may serve as reservoirs for mutans streptococci, preventive measures should be taken to control microbial concentrations at these sites. This study estimated the influence that sealing permanent first molars would have on the levels of mutans streptococci and lactobacilli in saliva of healthy seven-year-old schoolchildren. Permanent first molars were sealed in 31 children without caries (NC group) and in 32 children with caries (C group). None of the children had caries in their permanent first molars. Conventional methods were used to count mutans streptococci and lactobacilli in saliva before applying the sealant and again at 4 and 12 weeks after application. Baseline counts of lactobacilli and mutans streptococci were significantly higher in the C group. A significant reduction in mutans streptococci was observed in the NC group at 4 and 12 weeks. It was concluded that fissure sealants in permanent first molars can help reduce salivary levels of mutans streptococci in children without caries.     

Preventing the transfer of Streptococcus mutans from primary molars to permanent first molars using chlorhexidine

PURPOSE: The purpose of this study was to determine if the application of 1% chlorhexidine-containing wax on primary molars during the period of eruption of the first permanent molars could prevent the transfer of certain oral flora, namely Streptococcus mutans, to the permanent molars. METHODS: Fourteen children with a mean age of 6.5 years (7 males and 7 females) were assigned into two groups: a chlorhexidine group (n=9) in which 1% chlorhexidine-containing wax was painted on primary molars on one side of the mouth; and a placebo wax group (n=5) in which a similar wax, but without chlorhexidine, was painted on primary molars on the other side of the mouth. Baseline saliva samples and pooled plaque samples from the primary molars on both sides of the dentition were obtained from the two treatment groups. Following treatment, plaque samples from the occlusal fissures of the first permanent molars on both sides of the dentition were obtained. The levels of S.mutans and other members of the oral flora on the treated sides (chlorhexidine or placebo) were compared with those on the untreated sides. RESULTS: The results showed that the proportions of S.mutans to S.sanguinis were significantly lower in the chlorhexidine-treated sides compared to the untreated (P=0.04) and in the chlorhexidine-treated patients compared to placebo (P=0.029). CONCLUSIONS: Since lower mutans to sanguinis ratios have been associated with lower caries experience, treating primary molars with 1% chlorhexidine wax during eruption of permanent first molars may be a simple means for shifting the fissure flora of the permanent molars towards a more favorable balance.     

The persistence of Streptococcus mutans in nasopharyngeal carcinoma patients after radiotherapy

The aim of the study was to examine the persistence of oral Streptococcus mutans in nasopharyngeal carcinoma patients after radiotherapy. Ten subjects, ranging in age from 20 to 67 years, participated. DMFT/DMFS, salivary level of mutans streptococci and oral health status were recorded. Pooled plaque samples were obtained from the cervical margins and the interproximal regions of all the teeth and the occlusal surfaces of the molars prior to, immediately after, 3 and 6 months after the completion of radiotherapy. At least 10 colonies of S. mutans were isolated from each subject and totally 645 isolates were genotyped by restriction endonuclease analysis. The results showed that the salivary level of S. mutans increased significantly with the reduction of salivary flow rate after radiotherapy. Each subject had at least 1 genotype of S. mutans isolated throughout the follow-up period. In 3 subjects who initially carried 2 or more genotypes, 1 or 2 genotypes of S. mutans could not be detected 3 months after treatment. Moreover, the genotypes that became undetectable were predominant bacteria in the first sampling. The result indicated that most S. mutans genotypes were persistent after radiotherapy but some genotypes that might not adapt to the alteration of oral environment became undetectable.     

Tracing genotypes of mutans streptococci on tooth sites by random amplified polymorphic DNA (RAPD) analysis

The aim of this study was to clarify the distribution and persistence of mutans streptococci on different tooth sites in the same oral cavity. Thirteen subjects, aged 20-40 years, were examined. Salivary levels of mutans streptococci, caries prevalence, oral hygiene habits and status of tooth surfaces sampled were recorded. Plaque samples were obtained from four sites, the mesial and buccal surfaces of the first permanent molar on the right side of the lower jaw (46m and 46b), the distal surface of the first permanent premolar (24d) and the mesial surface of the second permanent premolar (25m) on the left side of the upper jaw, using sterile toothpicks on two occasions at 4-7-month intervals. The samples were cultivated on site-specific Strip mutans. Up to 10 colonies/site were isolated when present and genotyped by random amplified polymorphic DNA (RAPD) analysis, after species identification with PCR. Genotyping was also performed by restriction endonuclease analysis (REA) on 148 isolates, and results were consistent with the RAPD results. Most mutans streptococcus-positive samples were obtained from 46m. Within each individual, the same genotype occurred on at least two sites on all but one sampling occasion. A maximum of seven different genotypes were found in an individual. For a particular tooth site, four genotypes occurred simultaneously and taking both sampling occasions together the maximum was six different types. The same genotypes/types were found again after 4-7 months on 25 sites in 12 subjects. Fifteen sites were mutans streptococcus-positive on only one sampling occasion. The results indicate that several different genotypes of mutans streptococci colonize a tooth site, and that the same genotype colonizes several sites in the same oral cavity. Persistence of genotypes on a site for several months and interindividual differences in the occurrence of genotypes were also found.     

Effect of 40% chlorhexidine varnish on mutans streptococci counts in pits and fissures of permanent first molars

OBJECTIVES: This study aimed to test the following hypotheses: (1) a carry-over effect of EC40 does not occur in a split-mouth model, (2) two consecutive applications of EC40 varnish with an interval of 3 months per year has a better inhibiting effect on mutans streptococci in pit and fissure plaque of permanent first molars of 6-7-year olds than a repeated application at each 6 months and (3) EC40 exerts an inhibiting effect on mutans streptococci for at least a 6-month duration. METHODS: Using a split-mouth design, test molars received EC40 on fissures and pits and control molars remained without treatment. One group of test molars received EC40 at baseline, 6, 12 and 18 months and another group at baseline, 3, 12 and 15 months. Plaque samples were taken from pits and fissures of test and control molars at baseline, 6, 9, 12 and 24 months. A mixed ANOVA model was used to analyze the data. RESULTS: The first hypothesis was accepted, the second rejected and the third accepted. CONCLUSIONS: Twice a year EC40 application on pits and fissures of permanent first molars of 6-7-year-old children can significantly reduce mutans streptococci numbers for a 6-month period, but the reductions were small.     

Relationship between mutans streptococci in saliva and their colonization of the tooth surfaces

The relationship between the salivary concentration of mutans streptococci and their prevalence on different tooth surfaces was studied in 114 subjects. Plaque samples were obtained from all tooth surfaces in the dentition and the infection magnitude of mutans streptococci was determined. The salivary concentrations of mutans streptococci correlated significantly with the number of colonized tooth surfaces and with the infection level of mutans streptococci for individual teeth or groups of tooth surfaces. The highest correlation values were found for buccal and approximal surfaces and for molars followed by premolars and anterior teeth. The 10 tooth surfaces best reflecting the salivary levels of mutans streptococci were 5 buccal and 5 approximal sites, 6 of them localized on maxillary posterior teeth. A significant positive relationship was noted between the prevalence of mutans streptococci in saliva and on the dorsum of the tongue.     

Comparison between different methods for sampling cariogenic microorganisms in persons with exposed root surfaces

The levels of lactobacilli, mutans streptococci and the group of Actinomyces viscosus and Actinomyces naeslundii in a 15-s rinse were compared with the levels of these bacteria in paraffin-stimulated saliva and in pooled plaque from exposed root surfaces. Samples were obtained on 2 occasions from 30 subjects. The levels of lactobacilli, mutans streptococci and Actinomyces spp. in the rinse correlated strongly with the levels in the saliva (r=0.95, r=0.87, r=0.66 respectively). The mean levels of lactobacilli, mutans streptococci and Actinomyces spp. per ml were about 5, 10 and 4 limes higher respectively in the saliva than in the rinse medium. The correlations between the rinse levels and the levels in plaque were O.68, 0.65 and 0.42 but the correlations between saliva and plaque levels were even weaker (0.53, 0.56 and 0.38). The results indicate that a 15-s oral rinse can be as useful as saliva sampling when discriminating between high and low levels of caries-associated microorganisms in root surface plaque. The rinse method has definite advantages compared to saliva sampling in persons with low salivary secretion rate or difficulties to chew.     

Microbial flora associated with presence of root surface caries in periodontally treated patients

Abstract — Examination of saliva and dental plaque was carried out in 35 adults who had been treated for periodontal disease 3 yr earlier. Plaque samples were collected from approximal and buccal sound and carious root surfaces. The samples were analyzed for the presence and proportions of members of Streptococcus, Lactobacillus and Actinomyces. The results showed a low prevalence of root surface caries and a low level of salivary mutans streptococci and lactobacilli. From subjects with root caries there was a not statistically significant tendency to higher proportional levels of mutans streptococci in plaque from carious root surfaces than from caries-free surfaces. An inverse significant relationship between noncarious and carious root surfaces was noted for S. sanguis. The population of A. viscosus and A. naeslundii was similar in plaque samples from sound and carious sites but showed elevated levels in the subjects with five or more new root surface lesions.     

Microbial flora associated with presence of root surface caries in periodontally treated patients

Examination of saliva and dental plaque was carried out in 35 adults who had been treated for periodontal disease 3 yr earlier. Plaque samples were collected from approximal and buccal sound and carious root surfaces. The samples were analyzed for the presence and proportions of members of Streptococcus, Lactobacillus and Actinomyces. The results showed a low prevalence of root surface caries and a low level of salivary mutans streptococci and lactobacilli. From subjects with root caries there was a not statistically significant tendency to higher proportional levels of mutans streptococci in plaque from carious root surfaces than from caries-free surfaces. An inverse significant relationship between noncarious and carious root surfaces was noted for S. sanguis. The population of A. viscosus and A. naeslundii was similar in plaque samples from sound and carious sites but showed elevated levels in the subjects with five or more new root surface lesions.     

Genotypes of mutans streptococci tend to persist in their host for several years

The aim of this study was to evaluate the consistency of the prevalence of mutans streptococci in a group of Swedish families. Eleven families, which had previously been examined for genotypes of mutans streptococci, were re-examined after 2-5 years. The families consisted of mother, father and a child (mean age 7.2 years at the follow-up examination). One father did not participate. Pooled plaque samples were obtained from buccal and occlusal surfaces. Isolates of mutans streptococci were genotyped using chromosomal DNA digested with restriction endonuclease HaeIII, separated by gel electrophoresis and visualised through UV illumination after ethidium bromide staining. Comparing the DNA fingerprints of mutans streptococci found at baseline and follow-up, 9 children harboured one or two genotypes which were similar on the two sampling occasions. Two of these children had also gained a genotype. The remaining 2 children had lost a genotype each and 1 of them had gained two new genotypes. All 21 adults showed one or two genotypes identical to those found at baseline. Nine of these 21 adults had also lost one genotype. Four of these 9 and additionally 4 of the remaining adults showed one or two new genotypes. Six mother-child pairs shared a genotype at baseline and this pattern remained for five pairs at the end of the study. The results suggest that genotypes of mutans streptococci have a fairly high degree of consistency in children between 3 and 8 years of age as well as in adults, indicating persistence of the strains. However, the results also indicate that some subjects may gain and/or lose genotypes.     

Effect of Cervitec on mutans streptococci in plaque and on caries formation on occlusal fissures of erupting permanent molars

The aim of this study was to evaluate the effect of Cervitec on the abundance of mutans streptococci (MS) in occlusal dental plaque and on 2-year caries increment of partly erupting first permanent molars. Sixteen healthy schoolchildren aged 6-8 years, with at least 2 sound contralateral partly erupted permanent molars, received diet counselling and daily parental supervised toothbrushing with a fluoride dentifrice. Stimulated saliva samples were collected at baseline and after 1 year to evaluate MS levels. In a split-mouth design, Cervitec varnish was applied to one of the teeth at baseline and after 3 and 6 months, while the other tooth in the same jaw was a control. At the 9-month follow-up the teeth were in occlusal contact. At this time, varnish was not applied. At 3 and 6 months after the first application of varnish a significant suppression of MS was observed in plaque. Caries investigations, performed at baseline and every 3 months during the 2 years after the start of the study, showed that all the teeth treated with the varnish were free of caries after 2 years, whereas 8/16 control teeth developed incipient caries. In conclusion, our results suggest that treatment with Cervitec reduces MS in plaque on erupting permanent molars and can lead to a significant decrease in caries incidence.     

Continuous effect of pit and fissure sealing on S. mutans presence in situ.

PURPOSE: The effect of sealants on S. mutans presence in situ was investigated. METHODS: Four intact, fully erupted first permanent molars in each of 74 children, aged 6-8 years were required for inclusion in the study. Baseline examination included deft and plaque index. S. mutans presence on occlusal surfaces of the molars was evaluated, using a microbial replica method. Immediately after sealing the first permanent molars on one side, S. mutans presence in situ was re-evaluated, as well as three and six months thereafter. Three months after the initiation of the study, S. mutans presence was evaluated on the molars of the unsealed side, which were consequently sealed and re-evaluated immediately, and three months later. RESULTS: Positive correlation was found between deft scores, plaque indices and microbial replica values, at baseline. Sealing caused a significant reduction in S. mutans levels on the treated occlusal surfaces, in vivo (P < 0.001), which lasted, in most cases, up to six months. CONCLUSIONS: The data suggest that sealants enable a prolonged reduction of S. mutans presence in situ, indicating an additional prevention effect, by reducing one source of dissemination.     

Genotyping shows different strains of mutans streptococci between father and child and within parental pairs in Swedish families

The purpose of this study was to investigate whether there was an intrafamilial similarity of mutans streptococcal strains in some Swedish families using chromosomal DNA fingerprinting. Plaque samples were obtained from buccal and occlusal surfaces of 25 three-year-old children, their mothers and 18 fathers. The colonization levels of mutans streptococci were estimated with the "Strip mutans" test, and caries experience was scored by decayed, missing and filled teeth or decayed, extracted and filled teeth. Interviews about medical history, diet regimes, breastfeeding and care of the child were performed. In 11 families isolates of mutans streptococci were detected in all three individuals. These isolates were serotyped by immunofluorescent technique and genotyped using the restriction endonuclease Hae III. The results showed that 5 children harbored mutans streptococci genotypes different from their parents. Six children showed genotypes identical to their mothers. None of the children harbored genotypes similar to their fathers, even though two thirds of the fathers had high or very high mutans streptococci levels. No matching of genotypes was observed within the 11 parental pairs. Mothers as primary caregivers with high "Strip mutans" scores were more often observed in the group with identical genotypes within the mother-child pairs, the "matching group", than in the "no-matching group". These data indicate that the fathers and the children had not acquired each others' strains of mutans streptococci nor had the spouses. The results suggest that the children acquired mutans streptococci both from outside and inside the family.     

Prevention of pit and fissure caries using an antimicrobial varnish: 9 month clinical evaluation

OBJECTIVE: The purpose of this study was to determine whether Cervitec--a chlorhexidine--containing varnish could reduce the development of pit and fissure caries in children. METHODS: One hundred children each in age groups 7-8 and 12-14 years were selected from schools in Riyadh, Saudi Arabia. To be included in the study, each child had to have at least two sound contra-lateral first or second permanent molars with deep fissures. A split mouth method was used with one test tooth and one control within the same jaw. The left or the right side was selected randomly for test or control. The plaque samples from the occlusal surfaces of the test and control and the saliva samples were collected at baseline examination and after 9 months to estimate the number of Streptococcus mutans by the strip mutans method of Jensen and Bratthall (Jensen B, Bratthall D. A new method for the estimation of mutans streptococci in human saliva. Journal of Dental Research 1989;68:468-471). Cervitec varnish containing 1% chlorhexidine (CHx) and thymol was applied at baseline, at 3-4 months and at 6 months to the test tooth after isolation while the control had prophylaxis using cotton pellet in water each time the varnish was applied to the test tooth. Caries examination of the test and control followed after 9 months, according to the criteria and methods of WHO (World Health Organization. Oral Health Surveys. Basic Methods 4th ed., Geneva, WHO 1997).The blind technique was used in the diagnosis of caries and in the examination of the S. mutans count at the end of the study. RESULTS: Ninety four of the 7-8 year old and 86 of the 12-14 year old children completed the study. The results showed that the caries increment in both control groups of teeth after 9 months is significantly higher than in the test teeth (McNemar test: chi2 = 11.60, P < 0.001). The rate of caries development in a fissure was significantly correlated to the plaque mutans score of that fissure and there was considerable reduction in the S. mutans count of the plaque in the test teeth compared with the control (Spearman Rank Correlation: P < 0.001). CONCLUSION: It is concluded that the CHx varnish reduced the development of fissure caries significantly.     

Occlusal caries detection in permanent molars according to WHO basic methods, ICDAS II and laser fluorescence measurements

This epidemiological study aimed to compare the diagnostic outcome of the WHO criteria, ICDAS II criteria, laser fluorescence measurements, presence of plaque and roughness as activity scores on occlusal fissures and buccal/palatal pits of the first permanent molars. The study involved 311 children between 8 and 12 years of age from the Ennepe-Ruhr District in North Rhine-Westphalia, Germany. The surface-related caries status was registered according to the WHO basic method criteria (1997). Additionally, pit and fissure sealants, the ICDAS II visual criteria, the DIAGNOdent reading, plaque retention and surface roughness were documented. Caries experience was 1.0 (+/-2.5) DMFS. About 70% of the examined students had no obvious dentin caries in the permanent dentition (DMFS = 0). Sealants were registered on 1.4 (+/-1.7) occlusal fissures and 0.4 (+/-0.9) palatal/buccal pits. Noncavitated caries lesions were recorded as ICDAS II score 1-4 on 1.8 (+/-1.6) fissures and 1.5 (+/-1.4) pits. The comparison of the diagnostic methods suggests a relationship between higher ICDAS II scores/DIAGNOdent values and a proportional increase in the occurrence of plaque as well as in the number of rough surfaces. In conclusion, this study showed the diagnostic potential of the ICDAS II criteria in comparison to the traditional WHO criteria by means of the noncavitated caries lesions additionally detected. The DIAGNOdent use in field studies that already apply detailed visual criteria seems to bring limited additional information. While the presence of plaque provides information for the caries activity assessment more work is required to provide information about the contribution of surface roughness.     

Transmission of mutans streptococci in adults within a Chinese population

The purpose of this study was to investigate whether there was transmission between adults in Chinese families using chromosomal DNA fingerprinting. Plaque samples were obtained from buccal and occlusal surfaces of 11 married couples. The colonization levels of mutans streptococci were estimated as colony-forming units per milliliter, and caries experience was scored by decayed, missing and filled teeth. Information about medical history, diet regimes and age at marriage was obtained. The isolates were serotyped by biochemical test and genotyped using the restriction endonuclease HaeIII. The procedure was repeated after 3 months. The results showed that 1 couple had the same genotype of mutans streptococcus at the first examination, but this could not be repeated for the husband who had lost his mutans streptococci at the second examination. On the contrary, another couple that did not have the same mutans streptococcal genotype at the beginning had the same genotype after 3 months. No matching of genotypes was observed within 8 couples. In 1 male, no mutans streptococci were detected, therefore that couple was not considered. These data indicate that spouses had a chance to be infected by strains of mutans streptococci from another person. The results suggest that there may be transmission between adults in Chinese families, but it may be difficult for mutans streptococci to colonize another mouth permanently.