Correlation of level and duration of Streptococcus mutans infection with incidence of dental caries

A Co-Association of Streptococcus mutans and Veillonella parvula/dispar in Root Caries Patients and In Vitro Biofilms

Root caries in geriatric patients is a growing problem as more people are maintaining their natural teeth into advanced age. We determined the levels of various bacterial species previously implicated in root caries disease or health using quantitative real-time PCR in a pilot study of 7 patients with 1 to 4 root caries lesions per person. Levels of 12 different species on diseased roots compared to healthy (contralateral control) roots were measured. Four species were found at significantly higher levels on diseased roots (Streptococcus mutans, Veillonella parvula/dispar, Actinomyces naeslundii/viscosus, and Capnocytophaga granulosa) compared across all plaque samples. The level of colonization by these species varied dramatically (up to 1,000-fold) between patients, indicating different patients have different bacteria contributing to root caries disease. Neither of the two species previously reported to correlate with healthy roots (C. granulosa and Delftia acidovorans) showed statistically significant protective roles in our population, although D. acidovorans showed a trend toward higher levels on healthy teeth (P = 0.08). There was a significant positive correlation between higher levels of S. mutans and V. parvula/dispar on the same diseased teeth. In vitro mixed biofilm studies demonstrated that co-culturing S. mutans and V. parvula leads to a 50 to 150% increase in sucrose-dependent biofilm mass compared to S. mutans alone, depending on the growth conditions, while V. parvula alone did not form in vitro biofilms. The presence of V. parvula also decreased the acidification of S. mutans biofilms when grown in artificial saliva and enhanced the health of mixed biofilms.

Oral Microbiome and Dental Caries Development

Dental caries remains the most prevalent oral disease worldwide. The development of dental caries is highly associated with the microbiota in the oral cavity. Microbiological research of dental caries has been conducted for over a century, with conventional culture-based methods and targeted molecular methods being used in order to identify the microorganisms related to dental caries. These methods' major limitation is that they can identify only part of the culturable microorganisms in the oral cavity. Introducing sequencing-based technology and bioinformatics analysis has boosted oral microbiome research and greatly expanded the understanding of complex oral microbiology. With the continuing revolution of molecular technologies and the accumulated sequence data of the oral microbiome, researchers have realized that microbial composition alone may be insufficient to uncover the relationship between caries and the microbiome. Most updated evidence has coupled metagenomics with transcriptomics and metabolomics techniques in order to comprehensively understand the microbial contribution to dental caries. Therefore, the objective of this article is to give an overview of the research of the oral microbiome and the development of dental caries. This article reviews the classical concepts of the microbiological aspect of dental caries and updates the knowledge of caries microbiology with the results of current studies on the oral microbiome. This paper also provides an update on the caries etiological theory, the microorganisms related to caries development, and the shifts in the microbiome in dental caries development.

Genotypic diversity and acidogenicity of Streptococcus mutans in Down syndrome children

AIMS

To evaluate the genotypic diversity and acidogenicity of Streptococcus mutans (S. mutans) and the potential association of these factors with dental caries experience in children with DS compared to non-DS children (controls).

METHODS AND RESULTS

Seventeen children (age 6-12 years) with high salivary S. mutans counts (> 2.5 × 10⁵ CFU/mL) were selected and divided into two groups: DS and non-DS. Five children in each group were caries-free, while the remainder had elevated caries experience. S. mutans isolates were obtained from each participant. The genotypic profile of the isolates was analyzed with the AP-PCR methodology. The acidogenicity of a representative strain from each genotype of S. mutans was also evaluated. DS children had 16 different S. mutans genotypes, while the control group had 21. Twelve genotypes were present in both groups and one of them was associated with caries-free status (P < .05). Although the acidogenicity of the genotypes found in DS children was significantly lower (P < .05) compared to controls, this fact was not associated with caries experience in both groups.

CONCLUSIONS

DS children have a lower S. mutans genotypic diversity and genotypes with lower acidogenicity than those of non-DS children. However these findings were not associated with their caries experience.

Oral health in Alzheimer's disease: a multicenter case-control study

OBJECTIVES

The aim of this case-control study was to carry out an oral health assessment on a group of Alzheimer's patients and to establish a hypothesis regarding the implication of the characteristics of the disease and the treatment of oral health.

MATERIALS AND METHODS

A total of 70 Alzheimer's patients, residents at the Alzheimer Center Reina Sofia Foundation (Madrid, Spain) and at the Alzheimer State Reference Center (Salamanca, Spain), and 36 controls (companions/acquaintances), were studied by oral examination and saliva sampling. The oral health indices DMFT/DMFS, CPI, the prosthetic condition, oral hygiene, saliva volume, and pH, as well as the specific microbiological parameters governing the risk of developing caries were assessed.

RESULTS

Alzheimer's patients exhibited, as compared to the control group, (1) fewer teeth (10.9 ± 10.5 vs 23.7 ± 6.5), (2) fewer obturations (2.2 ± 3.4 vs 6.6 ± 5.6), (3) fewer periodontally healthy sextants (0.1 ± 0.4 vs 1.4 ± 2.2), (4) worse oral hygiene (43.1 vs 72.2% brushed), (5) greater use of removable prostheses (47.8 vs 8.4%), (6) higher incidence of candida infection (11.8 vs 0.0%) and cheilitis (15.9 vs 0.0%), (7) lower salivary flow (0.6 ± 0.6 vs 1.1 ± 0.6), and (8) lower buffering capacity (46 vs 80%).

CONCLUSIONS

After taking into account the influence of age, Alzheimer's patients had worse oral health (caries and periodontal disease), more mucosal lesions (cheilitis and candidiasis), and worse saliva quantity and quality.

CLINICAL RELEVANCE

Clinicians should be aware of the implications of Alzheimer's disease in oral health, in order to stablish the effective preventive measures and the optimal treatment plan.

Comparison of the Effect of Fluoride Varnish, Chlorhexidine Varnish and Casein Phosphopeptide- Amorphous Calcium Phosphate (CPP-ACP) Varnish on Salivary Streptococcus mutans Level: A Six Month Clinical Study

INTRODUCTION

Dental caries is the most widespread disease which has a multi factorial origin. Streptococcus mutans is considered to be the chief pathogen in its development. Different varnishes are available which can be used for the prevention of the carious process.

AIM

To compare the effect of fluoride varnish, chlorhexidine varnish and fluoride varnish containing Casein Phosphopeptide - Amorphous Calcium Phosphate (CPP-ACP) on salivary Streptococcusmutans count in children with mixed dentition over a period of six months.

MATERIALS AND METHODS

Seventy two children of age 6-12 years with mixed dentition were selected fulfilling inclusion and exclusion criteria and divided into three groups: Group I- Fluoride varnish group; Group II- Chlorhexidine varnish group; Group III- MI varnish (fluoride varnish containing CPP-ACP) group. After thorough oral prophylaxis and restorative treatment the varnishes were applied to the teeth once a week for four consecutive weeks in the respective groups. Salivary Streptococcus mutans count (CFU/ml of saliva) was estimated at baseline, 1 month, 3 months and 6 months after varnish application. Bonferroni post-hoc test and paired t-test for inter group and intra group comparison was used in the study.

RESULTS

A statistically significant reduction in salivary S. mutans colony count was seen with all three groups at all the different time intervals. Maximum reduction was noted in chlorhexidine varnish group at all the intervals after varnish application.

CONCLUSION

Prevention of dental caries plays a vital role in paediatric dental practice. The use of dental varnish has proved to be effective in reducing the dental caries. Chlorhexidine varnish was found to show maximum reduction in salivary S. mutans count for six month period, when compared to MI varnish and fluoride varnish. Thus, chlorhexidine varnish can be used as potent caries inhibiting agent and promote good oral health.

Clinical Assessment of a New Caries Activity Test Using Dental Plaque Acidogenicity in Children under Three Years of Age

OBJECTIVES

The aim of this study was to assess the validity of a new caries activity test that uses dental plaque acidogenicity in children with deciduous dentition.

STUDY DESIGN

Ninety-two children under the age of three years old underwent clinical examination using the dft index and examinations with two caries activity tests. Plaque samples for the new Cariview(®) test and the saliva sample for the conventional Dentocult SM(®) test were collected, incubated, and scored according to each manufacturers' instruction. The data were analysed using ANOVA and Spearman correlation analyses to evaluate the relationships between the test results and the caries experience.

RESULTS

The mean dft index of all of the subjects was 4.73, and 17.4% of the subjects were caries-free. The levels of caries risk based on the new Cariview test score significantly increased with the caries experience (p < 0.01). The test results revealed a stronger correlation with caries indices (dft and dt index) than the conventional SM colony counting method (r = 0.43, r = 0.39, p < 0.01).

CONCLUSIONS

The new caries activity test to analyse the acidogenic potential of whole microorganisms from dental plaques can be used to evaluate caries risk in children with deciduous teeth.

Dental caries and associated factors in twins with Down syndrome: a case report

Down syndrome (DS) is the most common genetic disorder in humans, but its incidence in monozygotic twins is extremely rare. The aim of this study was to determine the factors associated with dental caries in a pair of monozygotic twin girls with DS, where one had caries experience and the other did not. Clinical examination, salivary Streptococcus mutans (S. mutans) levels and their genotypic diversity, the biochemical composition of the dental biofilm, the frequency of sucrose consumption, and toothbrushing habits were assessed from the twin girls. Twin with caries experience showed higher levels of S. mutans in the saliva and lower concentrations of calcium, phosphate, and fluoride and higher concentrations of extracellular polysaccharides in the biofilm compared to her sister. Genotypic diversity of S. mutans was also higher in the twin with caries experience. Dental biofilm composition showed different patterns of cariogenicity between the two sisters, which may also by itself explain the difference in the dental caries between them.

Effect of Chewing Xylitol Containing and Herbal Chewing Gums on Salivary Mutans Streptococcus Count among School Children

Background:

The present study aims to assess and compare the reduction in salivary Mutans Streptococci counts after chewing Xylitol, herbal and placebo gums among high school children.

Methods:

The study was conducted among 72 school children (12–15 years) from 3 randomly selected schools (blocks). Xylitol, herbal and placebo gums were randomly allocated to 3 blocks. Subjects were instructed to chew one pellet four times a day for 21 days. The mean reduction in salivary Streptococcus mutans count was assessed.

Results:

The 100% Xylitol sweetened chewing gum “Xylitol”has shown statistically significant reduction in salivary Mutans Streptococci colony forming units at the end of 21 days (P < 0.01). The reduction was not statistically significant in herbal and placebo chewing gum.

Conclusions:

Hundred percentage Xylitol sweetened chewing gum was found to be more effective in reducing salivary Mutans Streptococci count when compared to herbal and placebo chewing gums.

Chlorhexidine treatment for the prevention of dental caries in children and adolescents

BACKGROUND

Dental caries (tooth decay) is a common disease that is preventable by reducing the dietary intake of free sugars and using topical sodium fluoride products. An antibacterial agent known as chlorhexidine may also help prevent caries. A number of over-the-counter and professionally administered chlorhexidine-based preparations are available in a variety of formulations and in a range of strengths. Although previous reviews have concluded that some formulations of chlorhexidine may be effective in inhibiting the progression of established caries in children, there is currently a lack of evidence to either claim or refute a benefit for its use in preventing dental caries.

OBJECTIVES

To assess the effects of chlorhexidine-containing oral products (toothpastes, mouthrinses, varnishes, gels, gums and sprays) on the prevention of dental caries in children and adolescents.

SEARCH METHODS

We searched the Cochrane Oral Health Group Trials Register (25 February 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 12), MEDLINE via OVID (1946 to 25 February 2015), EMBASE via OVID (1980 to 25 February 2015) and CINAHL via EBSCO (1937 to 25 February 2015). We handsearched several journals placed no language restrictions on our search. After duplicate citations were removed, the electronic searches retrieved 1075 references to studies.

SELECTION CRITERIA

We included parallel-group, randomised controlled trials (RCTs) that compared the caries preventive effects of chlorhexidine gels, toothpastes, varnishes, mouthrinses, chewing gums or sprays with each other, placebo or no intervention in children and adolescents. We excluded trials with combined interventions of chlorhexidine and fluoride or comparisons between chlorhexidine and fluoride interventions.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted trial data and assessed risk of bias. We resolved disagreements by consensus. We contacted trial authors for clarification or additional study details when necessary. The number of included studies that were suitable for meta-analysis was limited due to the clinical diversity of the included studies with respect to age, composition of intervention, and variation in outcome measures and follow-up. Where we were unable to conduct meta-analysis, we elected to present a narrative synthesis of the results.

MAIN RESULTS

We included eight RCTs that evaluated the effects of chlorhexidine varnishes (1%, 10% or 40% concentration) and chlorhexidine gel (0.12%) on the primary or permanent teeth, or both, of children from birth to 15 years of age at the start of the study. The studies randomised a total of 2876 participants, of whom 2276 (79%) were evaluated. We assessed six studies as being at high risk of bias overall and two studies as being at unclear risk of bias overall. Follow-up assessment ranged from 6 to 36 months.Six trials compared chlorhexidine varnish with placebo or no treatment. It was possible to pool the data from two trials in the permanent dentition (one study using 10% chlorhexidine and the other, 40%). This led to an increase in the DMFS increment in the varnish group of 0.53 (95% confidence interval (CI) -0.47 to 1.53; two trials, 690 participants; very low quality evidence). Only one trial (10% concentration chlorhexidine varnish) provided usable data for elevated mutans streptococci levels > 4 with RR 0.93 (95% CI 0.80 to 1.07, 496 participants; very low quality evidence). One trial measured adverse effects (for example, ulcers or tooth staining) and reported that there were none; another trial reported that no side effects of the treatment were noted. No trials reported on pain, quality of life, patient satisfaction or costs.Two trials compared chlorhexidine gel (0.12% concentration) with no treatment in the primary dentition. The presence of new caries gave rise to a 95% confidence interval that was compatible with either an increase or a decrease in caries incidence (RR 1.00, 95% CI 0.36 to 2.77; 487 participants; very low quality evidence). Similarly, data for the effects of chlorhexidine gel on the prevalence of mutans streptococci were inconclusive (RR 1.26, 95% CI 0.95 to 1.66; two trials, 490 participants; very low quality evidence). Both trials measured adverse effects and did not observe any. Neither of these trials reported on the other secondary outcomes such as measures of pain, quality of life, patient satisfaction or direct and indirect costs of interventions.

AUTHORS' CONCLUSIONS

We found little evidence from the eight trials on varnishes and gels included in this review to either support or refute the assertion that chlorhexidine is more effective than placebo or no treatment in the prevention of caries or the reduction of mutans streptococci levels in children and adolescents. There were no trials on other products containing chlorhexidine such as sprays, toothpastes, chewing gums or mouthrinses. Further high quality research is required, in particular evaluating the effects on both the primary and permanent dentition and using other chlorhexidine-containing oral products.

Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months: a controlled observational study

Objective

The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment.

Material and Methods

Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account.

Results

Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively), independently of other variables.

Conclusion

The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment.

Comparative evaluation of chlorhexidine varnish and fluoride varnish on plaque Streptococcus mutans count--an in vivo study

AIM

The aim of the study was to assess and compare the effect of chlorhexidine varnish and fluoride varnish application on Streptococcus mutans counts in plaque of occlusal pits and fissures of permanent mandibular first molars.

MATERIALS AND METHODS

The study was an in vivo comparative study, conducted among 50 schoolchildren aged 7-8 years under a field setting. The 50 subjects were randomly allocated into two groups. Baseline plaque samples were collected from all the subjects followed by the application of two varnishes, Cervitec and Duraphat. The varnish was applied to pit and fissures of occlusal surface of mandibular first molar. The varnish application was carried out on the first day, fifth day and tenth day after baseline plaque sampling. Subsequent plaque samples were collected at the end of 1 month and at the end of 3 months after the varnish application.

RESULTS

The Cervitec varnish has shown a statistically significant reduction at the end of 1 month and at the end of 3 months (P < 0.05). Duraphat varnish did not show a statistically significant difference in reducing the plaque S. mutans count at the end of 1 month and third month (P > 0.05).

CONCLUSION

Cervitec varnish was found to be effective in reducing S. mutans count for a 3-month period, when compared to Duraphat varnish.

Approximal Caries Increment in Two Cohorts of Schoolchildren after Discontinuation of a Professional Flossing Program with Chlorhexidine Gel

We have in two earlier studies evaluated the effect of professional flossing with chlorhexidine (CHX) gel treatment, in 4- to 7-year-old preschool children and in 12- to 15-year-old teenagers. The mean caries reduction after 3 years was around 40% compared to placebo gel or no gel treatment. The aim of the present investigation was to follow up these two clinical studies. The preschool children were followed up to the age of 16 years and the teenager group to the age of 19. Of the total number of original children, 71 and 80% were available at the age of 16 and 19 years, respectively. At the 9-year follow-up, when the children were 16 years old, the former CHX group had still significantly lower mean DFS than the control group (p < 0.05). The differences in caries increment occurred between 7 and 12 years of age, whereas the number of new caries lesions during the next 4 years were almost the same in the three groups. At the 4-year follow-up, when the teenagers were 19 years old, DFS was 6.9 in the former CHX group compared to 10.4 in the control group (p < 0.05). The main conclusion of these two follow-up studies after 9 and 4 years, respectively, is that caries reductions obtained at the end of professional flossing with a 1% CHX gel were maintained.

Medically administered antibiotics, dietary habits, fluoride intake and dental caries experience in the primary dentition

OBJECTIVES

Dental caries continues to be a major public health problem in the US and other nations, particularly among younger children. Unfortunately, understanding of factors contributing to caries in this age group is incomplete and further studies are necessary. The purpose of this study was to assess factors related to extensive caries experience among children aged 4-7 years, including antibiotic use, dietary patterns, fluoride intakes, and tooth brushing habits.

METHODS

The case-control study was nested within a longitudinal cohort study of children's oral health. The larger cohort study collected data on fluoride intakes and behavioral factors, including antibiotic use and dietary patterns of children periodically from birth. A single dental examination was completed for each child at a time between the ages of 4-7 years. A case-control design was used to compare children with severe caries experience (6 or greater dmfs) to those with no caries experience. Cases (n = 39) included all who met the criteria and had sufficient longitudinal data (n = 39) while a control group was selected to have comparable mean age, exam dates, and an equal number of boys and girls.

RESULTS

Backward elimination logistic regression controlling for demographic variables showed severe caries experience to be related to greater regular pop/other sugared beverage intake, greater frequency of starch foods, and greater frequency of eating occasions. Mother's education and fluoride intake from water were inversely related to severe caries experience. Antibiotic use was generally higher in the control group, but was not significantly different than in the severe caries group.

CONCLUSIONS

Although we cannot rule out the possibility that antibiotics may be associated with increased or decreased caries risk, our data suggest that they play only a minor role in caries prevention compared to fluoride. Dietary sugar continues to be a significant risk factor for caries in the primary dentition.

Dental caries is a preventable infectious disease

Dental caries is the most common infectious disease affecting humans. The principal causative agents are a group of streptococcal species collectively referred to as the mutans streptococci of which Streptococcus mutans and Streptococcus sobrinus are the most important agents of human caries. This review outlines what is currently known about these ubiquitous pathogens and discusses novel methods for elimination of these bacteria from dental plaque.

Maintaining mutans streptococci suppression with xylitol chewing gum

BACKGROUND

One strategy for treating dental caries is to suppress oral mutans streptococci, or MS, with chlorhexidine, or CHX, mouthrinse. Oral MS levels, however, tend to quickly return to baseline values without further intervention. In this clinical study, the authors evaluated the effect of xylitol chewing gum on MS regrowth.

METHODS

The authors selected 151 subjects with elevated oral MS levels (> or = 105 colony-forming units per milliliter, or CFU/mL, of paraffin-stimulated saliva). Subjects rinsed with 0.12 percent CHX gluconate mouthrinse twice daily for 14 days. The authors then randomly assigned the subjects to one of three groups. Those in the test group (n = 51) chewed a commercial xylitol gum three times daily for a minimum of five minutes each time for three months. The placebo group subjects (n = 50) used a commercial sorbitol gum, and the control group subjects (n = 50) did not chew gum. The authors estimated MS load on the dentition using paraffin-stimulated saliva samples. The authors serially diluted the samples, plated them on selective media and incubated them anaerobically; they then enumerated the colonies under a stereomicroscope.

RESULTS

MS levels were not significantly different between the three groups at baseline (mean log CFU/mL +/- standard deviation: 5.4 +/- 0.7, 5.4 +/- 0.8, 5.2 +/- 0.7, respectively) nor after CHX therapy (2.7 +/- 0.8, 3.1 +/- 1.1, 3.0 +/- 1.1, respectively). After three months of gum chewing, the test group subjects had significantly lower salivary MS levels (3.6 +/- 1.2) than did the placebo (4.7 +/- 1.2) or control (4.4 +/- 1.3) group subjects.

CONCLUSIONS

Xylitol chewing gum appears to have the ability to prolong the effect of CHX therapy on oral MS.

CLINICAL IMPLICATIONS

Maintaining long-term caries-pathogen suppression is feasible with currently available commercial products and can be expected to result in significant caries inhibition.

Caries-risk assessment

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host (saliva and teeth), the microflora (plaque), and the substrate (diet), and a fourth factor: time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. These include caries experience (initial caries lesions and established caries defects, secondary caries and present caries activity), fluoride use, extent of plaque present, diet, bacterial and salivary activity and social and behavioural factors.

Human oral microbial ecology and dental caries and periodontal diseases

In the human oral cavity, which is an open growth system, bacteria must first adhere to a surface in order to be able to colonize. Ability to colonize a non-shedding tooth surface is necessary prior to any odontopathic or periodontopathic process. Complex microbe-host relationships occur and must be studied before the commensal-to-pathogenic nature of the human indigenous oral flora can be understood. Medical pathogens, if present in the appropriate host, always produce specific disease. Caries and periodontal diseases are conditional diseases, requiring numbers of certain indigenous species at various sites, particularly the tooth surface. In the case of caries, the condition is related to sugar consumption. Periodontal disease/s may require certain host and environmental conditions, such as local environment or nutritional factors in gingival crevicular fluids. Nonetheless, critical numbers of certain indigenous species must be present in order for these diseases to occur. The aim of this review is to understand the acquisition of the indigenous oral flora and the development of human dental plaque. The role of the salivary pellicle and adherence of indigenous bacteria to it are critical first steps in plaque development. Bacterial interactions with saliva, nutritional factors, growth factors, and microbial physiologic processes are all involved in the overall process of microbial colonization.

Etiology of nursing caries: a microbiologic perspective

A compelling body of scientific evidence supports the concept that nursing caries is an infectious and transmissible disease. This evidence makes a strong case to support the tenet that infants who are colonized by mutans streptococci, and who have feeding habits characterized by frequent and prolonged oral exposure to cariogenic substrates, are likely to have a drastic increase in their oral mutans streptococci populations. Such an increase is associated with a high risk for rampant dental caries. This evidence strongly suggests that the first step in the etiology of nursing caries is primary infection by mutans streptococci; the second step is accumulation of these organisms to pathogenic levels as a consequence of frequent and prolonged oral exposure to cariogenic substrates; and the third step is rapid demineralization and cavitation of enamel resulting in rampant dental caries. This three-step model might provide an important framework for the design of clinical trials targeted at prevention of nursing caries.

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.

How severe is the threat of caries to old teeth?

Caries is a bacterial infection caused by a complex interaction of biologic and behavioral factors. It is believed that caries is a major threat to teeth in old age, yet little information is available on the incidence and progress of carious lesions in elderly teeth. All too often caries is diagnosed after a visual and tactile examination of tooth structure without thought for the other factors essential to the initiation and support of an active lesion. Prospective studies have been conducted recently in Vancouver to quantify associations between the incidence of caries and many of the behavioral, bacteriologic, and physiologic factors potentially influencing oral health in old age. The results indicate that improvements in hygiene may hold the most promise for controlling this infection in an elderly population.

Mutans streptococci and lactobacilli in the elderly

The prevalence of salivary mutans streptococci and lactobacilli, salivary flow rate, and the type of dentition were studied in connection with a medical survey of 76-, 81-, and 86-yr-old inhabitants of Helsinki living at home. High bacterial counts were associated with low salivary flow rates. High counts of mutans streptococci (> 10(6) CFU/ml) were found in 68% of wearers of full dentures, as compared with 53% of subjects having natural teeth. High counts of lactobacilli (< 10(6) CFU/ml) were found in 44% of subjects having removable partial dentures and in 39% of subjects having natural teeth. The bacterial counts correlated neither with medicines taken daily nor with diseases among this population.

Potential efficacy of chlorhexidine against mutans streptococci and human dental caries

Chemotherapeutic agents have been considered as having potential for the prevention of dental caries. Several substances have been evaluated as possible candidates, but no antimicrobial agent, with the exception of fluoride, has received as much experimental attention as the bisbiguanide chlorhexidine. This substance represents, so far, the most effective and best-documented agent. To be effective against caries, therapeutic dosages of the antimicrobial agent have to be given for a sufficient but finite time period to sites with established cariogenic plaque. In studies where this principle has been used, the aim has been to eliminate or strongly suppress the population of mutans streptococci. Of various antimicrobial agents and methods tested, the most persistent reduction of mutants streptococci has been achieved by chlorhexidine varnishes, followed by gels and mouthwashes. The best clinical effect resulting in a considerable caries reduction has been obtained when persons highly colonized with mutans streptococci have been treated with gels and when the results of the antimicrobial measures have been verified by microbiological examination.

Caries risk assessment by a cross-sectional discrimination model

Although the prevalence of dental caries is continuing to decline, it still affects a majority of the US population and can be a serious problem for those afflicted. The objective of this project was to develop and perfect a model for assessment of risk of dental caries onset in children. In the first study, reported herein, a set of clinical, microbiological, biochemical, and socio-demographic variables was identified that distinguished, with an acceptable level of sensitivity and specificity, between children who had no previous caries experience and children who had high caries levels. A total of 313 children--age 12-15 years, 140 from a fluoridated community and 173 from a fluoride-deficient community--was selected on the basis of previous caries experience, either zero DMFS or high DMFS (> or = 6 in the fluoridated or > or = 8 in the fluoride-deficient community). Clinical exams for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride concentration. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of discriminant analyses, with use of seven key clinical and laboratory variables, it was possible for zero-DMFS subjects to e classified correctly (specificity) in 77.6% of cases in the fluoridated community and in 86.1% of cases in the fluoride-deficient community. High-caries subjects were classified as such (sensitivity) in 79.3% and 88.1% of cases, respectively.

Prevalence of dental caries in 4- to 5-year-old children partly explained by presence of salivary mutans streptococci

The correlation between dental caries and the number of oral mutans group streptococci (ms) present has been shown to be weak. The aim of this investigation was to study associations between caries experience (decayed, missing, and filled surfaces [dmfs]) and the number of ms in stimulated saliva, with emphasis on the level of disease and the confounding effect of regular intake of sweets, the presence of salivary lactobacilli, and oral hygiene. In some 2,700 4- to 5-year-old South African children of different ethnic origins, caries was diagnosed on the basis of World Health Organization criteria and saliva samples were analyzed for ms after cultivation on mitis salivarius-bacitracin agar and for lactobacilli by using the Dentocult kit. Oral hygiene was scored on the basis of the Greene and Vermillion simplified debris index, while data on intake of sweets were derived from extensive interviews. Pearson's coefficient of correlation was computed, and multiple regression analysis was performed to correct for confounding factors. The distribution of the children in the eight caries classes was strongly associated with the ms class (P < 0.001), with those in the lower ms classes generally having low dmfs scores and those in the higher ms classes having dmfs scores distributed over the whole range. The r value for the two variables was 0.25 for the total material; this was reduced to 0.18 by correction for confounding factors. The corresponding values for children with caries were 0.21 and 0.17, for those in the 1 to 6 dmfs interval they were 0.07 and 0.03, and for those in the 7 to 81 dmfs interval they were 0.16 and 0.14. The data imply that the explanatory values for ms, those for the lower caries interval not counted, ranged from 6 to 2%. The unexpected results for children with caries might be due to their distribution pattern. It is concluded that there is a need for reevaluation of ms as a risk factor in dental caries.

The University of North Carolina Caries Risk Assessment study: further developments in caries risk prediction

Over 4000 first and fifth grade children from the areas surrounding Aiken, South Carolina, and Portland, Maine, participated in a 4-yr study to develop caries risk assessment models. The predictors used at baseline included detailed clinical examinations, salivary microbiological tests, and sociodemographic and dental behavior data. Mean 3-yr caries increments in South Carolina were twice those in Maine. For the four risk assessment models (two grade cohorts at two sites) specificity values averaged 0.83 and sensitivity values averaged 0.60. Clinical predictors such as prior DMFS, pit and fissure morphology, and predicted caries risk status were the major contributors to the models.

Therapeutic effects of daily or weekly chlorhexidine rinsing on oral health of a geriatric population

The effects of a chlorhexidine rinse on salivary Streptococcus mutans, Lactobacillus, and Candida albicans counts and on periodontal conditions (gingival index, plaque index, pocket depths) were studied in 42 elderly subjects. Under supervision, they rinsed either daily or weekly for 6 weeks with a 0.12% chlorhexidine solution (Peridex). Saliva samples were taken for chemical and microbiologic examinations, and periodontal conditions were assessed at baseline, week 6, and 6 weeks after final rinse. Significantly lower S. mutans counts were found at week 6 for both rinsing groups (p less than 0.001). Lactobacillus and Candida counts were also generally lower at week 6, with the clearest improvement among persons with the highest counts of bacteria and yeast. Periodontal conditions were improved at week 6 (p less than 0.001) in both groups. Such improvements were not maintained 6 weeks after the rinsing regimen was completed. At baseline poor oral conditions were noticed, which placed most of the subjects at risk for tooth decay and periodontal disease. Without any other dental procedures but daily or weekly supervised rinsing, oral conditions were improved and this risk was reduced. Daily rinsing was not superior to weekly rinsing with 0.12% chlorhexidine.

Associations of microbiological factors and plaque index with caries prevalence and water fluoridation status

Plaque indices, numbers of mutans streptococci, lactobacilli and total viable flora in plaque and saliva were assessed as part of a large-scale cross-sectional study designed to determine the factors that are associated with high caries activity in children. Subjects, 12 to 15 years old, residing in areas where the water supplies were either fluoridated (n = 140) or fluoride-deficient (n = 173) were studied. Mutans streptococci and lactobacilli numbers in saliva were positively correlated with plaque index. Plaque indices were significantly higher in the high-caries group than in the zero-caries group of the fluoride-deficient community. In the fluoridated community, there was no difference in the plaque index between the zero- or high-caries groups. In each community, pooled dental plaque and saliva harbored fewer mutans streptococci and lactobacilli in the zero-caries than the high-caries group. Greater numbers of mutans streptococci were found in the dental plaque and saliva of the zero-caries subjects in the fluoridated community than in the fluoride-deficient community, suggesting that a greater caries challenge can coexist with zero-caries status in the fluoridated community.

Mutans streptococci in saliva and dental caries in children living in a high and a low fluoride area

The aim of this study was to obtain information about the quantitative distribution of salivary mutans streptococci and the relation to dental caries in children with contrasting levels of natural water fluoride. A total of 698 schoolchildren aged 12 yr were selected from areas with high (1.2 ppm) or low (0.1 ppm) fluoride concentration in the drinking water. They were all examined for the presence and number of mutans streptococci in saliva by a specially prepared plastic strip, the "Strip mutans" method, cultivated in a selective broth. Data on the caries experience were obtained from the dental records and from bite-wing radiographs. Mutans streptococci were identified in 82% of all children with no difference between the two areas. The number of mutans streptococci was however significantly (p less than 0.05) lower among the children from the high fluoride area than those from the low fluoride area. Children with no detectable or low levels (0-10 CFU) of mutans streptococci had less caries experience than children with moderate or high levels (11- greater than 500 CFU) in both areas investigated.

Longitudinal study of caries and cariogenic bacteria in an elderly disabled population

A 2-yr longitudinal study was conducted among elderly disabled residents of a longterm care facility. Each of the 50 subjects examined at the beginning of the study had a mean of 14 teeth, with a mean of 6 carious and 6 restored teeth, per person. Most of the subjects had very poor oral hygiene, and 26 of them had dental plaque that produced cultures of mutans streptococci and lactobacilli in excess of 10(5) CFU/ml. At the end of the first year, 40 subjects were examined again and, apart from a decrease in the mean number of carious root lesions per person, there was very little change in their dental or microbial status. Although only 18 subjects were available at the end of the second year, they presented with fewer carious lesions after 2 yr. The reduction in caries appeared to result from the remineralization of tooth structure, but new lesions did appear in 33% of the 1-yr group, and in 78% of the 2-yr group. This dynamic environment around the teeth produced a mean net incidence of one lesion in the first year, and three lesions over 2 yr. There was a significant (P less than 0.05) association between large (greater than 10(5) CFU/ml) numbers of mutans streptococci and the development of new lesions, but there was no association between the dental status of the subjects and the dental treatment they received. Overall, the results indicate that caries is not rampant in this population.

Salivary caries-related tests as predictors of future caries increment in teenagers. A three-year longitudinal study

The aim of the study was to evaluate the capability of caries-related salivary tests and a test based on past caries experience (baseline DFS) to select persons at high risk for caries. The subjects (n = 122) were 12-17 years old at the beginning of the study. Caries was registered and salivary samples were taken annually during the 3-study period. The 3-year caries increment was positively correlated to the baseline DFS (r = 0.46, p less than 0.001), salivary level of mutans streptococci (r = 0.30, p less than 0.001) and lactobacilli (r = 0.30, p less than 0.001), and combined level of mutans streptococci and lactobacilli (r = 0.39, p less than 0.001) and negatively correlated to the buffering capacity of saliva (r = -0.22, p less than 0.05). Tests based on either past caries experience or mutans streptococci or lactobacilli levels alone were not efficient in selecting persons at high risk for caries. Among the tests, DFS was the most sensitive and specific. A combination of either microbial test and DFS was more efficient to select persons at risk than various alternatives alone. The sensitivity was 84% and the specificity 62% for the combination of lactobacilli test and DFS and 71% and 79% respectively for the combination of mutans streptococci and DFS. In the former combination the positive prediction value was 43% and in the latter 56%.

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.

Salivary Streptococcus mutans and caries prevalence in Brazilian schoolchildren

The aim of the present study was to determine the levels of salivary Streptococcus mutans in Brazilian schoolchildren, and its possible correlation with caries prevalence. A positive correlation between different levels of S. mutans and caries prevalence was observed, individuals with high levels of S. mutans (greater than 100 colonies) had a DMFS significantly higher than those with low or no detectable S. mutans (0, 1-20, 21-40 colonies).

The University of North Carolina Caries Risk Assessment Study. I: Rationale and content

This article presents the rationale and content of a current study that seeks to improve methods to identify children at high risk to dental caries. It summarizes the results of the development of a 12-factor, preliminary caries prediction model based on data derived from the National Preventive Demonstration Program. Despite data limitations, the model produced a sensitivity of .5 and specificity of .8 for four-year caries increment prediction in first- and fifth-grade children. Data on a number of additional potential predictors are being collected in two sites to expand and improve the existing model. These factors are identified.

Caries prevalence and severity in the primary dentition and Streptococcus mutans levels in the saliva of preschoolchildren in South Africa

The caries prevalence (dmft) and severity (css) in 3-, 4-, and 5-yr-old children in South Africa were examined. Four levels of S. mutans in the saliva of 228 of these children was estimated by the spatula method. In all three age groups a statistically higher dmft and css was found with a S. mutans level of greater than 10(6) CFU/ml in saliva than at lower concentrations. At age 5 ANOVA showed significant differences between dmft and css at all S. mutans levels. A high concentration of S. mutans in the saliva may be an indicator of the high risk child at an early age.

Salivary levels of Streptococcus mutans and lactobacilli and dental caries experiences in a US adolescent population

Dental caries exams and saliva samples were obtained from 541 adolescents, aged 10-15, initially and after 17 months as part of a 3-yr longitudinal study investigating the relationships of dietary intakes, specific microorganisms in saliva, and the prevalence and incidence of dental caries. The mean DMFS score detected in these subjects initially was 4.61, and they developed an average of 1.38 new DMFS during the first 17-month period. Initially, S. mutans and lactobacilli were detected in 64% and 56% of these subjects, respectively. Subjects with low levels of S. mutans and lactobacilli had significantly lower initial DMFS scores and developed significantly fewer new DMFS than subjects with high counts. The predictive values of a positive result for S. mutans or lactobacilli assays were low (31% and 39%), but those for a negative result were high (81% and 84%).

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

Since the caries prevalence has not declined in Iceland as it has in other European countries, it was of interest to study the presence of cariogenic bacteria in Icelandic children. The prevalence of salivary mutans streptococci and lactobacilli was examined in 217 11- and 12-yr-old Icelandic children and was related to their caries prevalence. In 2% of the children mutans streptococci were not found whereas 31% and 35% of the 11-yr-olds and 12-yr-olds respectively carried more than 10(6) CFU per ml saliva. Lactobacilli were not detected in 8% of the children whereas 28% of the 11-yr-olds and 23% of the 12-yr-olds had more than 10(5) CFU per ml saliva. The mean caries prevalence (DFS), initial caries included, for 11-yr-olds was 21.6 and for 12-yr-olds 28.8. Both mutans streptococci and lactobacilli were significantly correlated to each other as well as to caries prevalence. An increased number of these microorganisms, especially the mutans streptococci, were associated with an increased DFS. Children with high salivary counts of mutans streptococci and lactobacilli showed four times higher DFS than children with low numbers. The magnitude of salivary cariogenic bacteria as well as caries prevalence was found to resemble the situation in Sweden 10 yr ago. S. mutans (serotype c/e/f) was carried by all mutans streptococci positive children. S. sobrinus (serotype d/g) was found in 60 children (30.2%). Children with both S. mutans and S. sobrinus had significantly higher salivary counts of mutans streptococci and lactobacilli as well as caries prevalence than children with only S. mutans.

Microbial conditions and caries increment 2 years after discontinuation of controlled antimicrobial measures in Swedish teenagers

The purpose of the present study was to examine the long-term effect of a special caries preventive program in teenagers. Over a 3-yr period directed and controlled antimicrobial treatment using Streptococcus mutans as an indicator organism resulted in a remarkable caries reduction especially in children with greater than 10(6) S. mutans per ml of saliva at the start of the study. Two years after discontinuation of the special preventive program 83 out of 101 subjects, 18-19 yr old, were reexamined. All the children had followed the same basic preventive program in the Dental Health Service. The number of S. mutans and lactobacilli per ml of saliva within and between control and test groups was with few exceptions practically the same as 5 yr earlier. During the posttreatment period the caries activity was similar in the control and test groups and lower than during the experimental years especially in the control group. Subjects with initial S. mutans level of greater than 10(6) CFU per ml of saliva continued to show incremental caries scores higher than those subjects with lower S. mutans levels.

Caries status and microbial conditions in children in 1973 and 1984

In 1973 all 9-12-yr-old children in a county in Sweden were examined with regard to caries prevalence, salivary Streptococcus mutans and lactobacilli. Eleven years later the same parameters were analyzed in 250 randomly selected children of the same age and from the same county. Both the number of cariogenic microorganisms and the caries prevalence were significantly lower in 1984 than in 1973 (P less than 0.001). The lower number of S. mutans and lactobacilli could be due to several factors and is probably one of the reasons for the low caries prevalence in the children in the present study.

Chlorhexidine compared with other locally delivered antimicrobials. A short review

Based on the association of bacterial plaque with the initiation of chronic gingivitis and progression of chronic periodontitis, chemical antiplaque agents have been employed both in prevention of periodontal disease and its treatment. In supragingival plaque control regimens, chlorhexidine has not been superceded as a chemical anti-plaque agent, although other compounds have been shown to be useful. The local side-effects of chlorhexidine and other cationic antiseptics, however, limit their long-term use for prevention. Extrinsic tooth staining in particular remains the greatest problem. Short-term anti-plaque uses for chlorhexidine include as an adjunct to mechanical cleaning in the initial oral hygiene phase of treatment, in situations where mechanical oral hygiene is difficult, including postsurgery, intermaxillary fixation, fixed orthodontic therapy, physically and mentally handicapped individuals, systemic diseases with oral manifestations such as leukaemia. More recent interest in chlorhexidine has resulted from the delivery of compounds subgingivally in the treatment of chronic periodontitis. Such methods have extended the use of chlorhexidine into areas inaccessible to the action of antimicrobial drugs delivered locally by conventional means, such as tooth brushing or mouth rinsing. Available evidence suggests that chlorhexidine may not be as effective as some antimicrobial drugs whose activity is more specific for those organisms considered particularly pathogenic to the periodontal tissues.

Impact of oral hygiene and use of fluorides on caries increment in children during one year

The aim of this study was to assess the modifying effect of oral hygiene, and the use of fluorides on caries increment in children when frequency of meals, intake of sugars and prevalence of lactobacilli and S. mutans in the saliva were known. In 8- and 13-yr-olds it was possible to show that children with a low caries increment (0-2 surfaces) had lower mean values for frequency of meals, daily sucrose consumption and prevalence of lactobacilli and S. mutans in the saliva than children with a high caries increment (greater than or equal to 3 surfaces). There were higher mean values in the low caries-increment groups for toothbrushing frequency, use of fluoridated toothpaste and NaF-mouthrinse. Gingival bleeding index (GBI %) was used as an objective measure of oral hygiene and revealed statistically significant differences between the two groups in both age groups (P less than 0.05, P less than 0.01) with the highest scores recorded in the high caries-increment groups. Using as discriminating variables number of meals/day, daily consumption of sucrose and other sugars and number of lactobacilli and S. mutans in the saliva, 77% of the 8-yr-olds and 70% of the 13-yr-olds were correctly classified with regard to net caries increment. If GBJ %, tooth-brushing frequency, use of fluoridated toothpaste and NaF-mouthrinse were included in the analysis another 4% of the 8-yr-olds and 11% of the 13-yr-olds could be correctly classified.

Salivary counts of lactobacilli and Streptococcus mutans in caries prediction

The aim of the study was to evaluate whether a combination of tests of salivary counts of lactobacilli and S. mutans would be of more value in caries prediction than each test used by itself. The study was done on 179 children 8 and 13 yr old. The mean caries increments in these children were 1.5 and 3.7 new caries lesions per year, respectively. The results showed that these tests or a combination of them are not specific in selecting caries risk patients. A combination of the two tests, however, was more efficient in selecting these patients than each test used by itself.

Support for and implications of the specific plaque hypothesis

The role of specific microorganisms in dental caries is reviewed. A considerable amount of evidence supports the association between organisms of the Streptococcus mutans group and caries incidence and prevalence. The cariogenic potential of S. mutans is probably due to the unique combination of properties with which this microorganism is endowed. The pathogenic potential can be modified by changes in the environment. Lactobacilli play a major role in the development of a lesion. The specific plaque hypothesis has important implications because the association between S. mutans, lactobacilli and dental caries can be used in diagnosis, treatment and prevention of the disease in groups of subjects as well as in the individual case.

Lysozyme-mediated de-chaining of Streptococcus mutans and its antibacterial significance in an acidic environment

The ability of physiological amounts of lysozyme to de-chain two serotype c strains of Streptococcus mutans was determined. Both human and hen lysozymes were equally effective in chain breakage of S. mutans DPR and S. mutans DJR. De-chaining did not affect growth of cultures, but resulted in finely dispersed suspensions, at stationary phase, which were visibly different from untreated cultures. Less than 50 micrograms lysozyme per ml culture medium reduced chain length to virtually all diplococci and single cells, and this chain disruption increased total viable cell count. De-chaining required an active enzyme indicating that a degree of hydrolysis of the peptidoglycan occurred at the septae of the streptococci. De-chained S. mutans did not survive as well as streptococci of normal chain length when incubated under acidic conditions (pH 5.5), but gross cellular lysis was not apparent. The reduced aciduric property of the disrupted chains may have been due to a participation of autolysins or to a lethal triggered by the lysozyme-damaged peptidoglycan. De-chaining may be a mechanism by which lysozyme could regulate the levels of S. mutans in acidogenic plaque samples.