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

Comparative evaluation of salivary microbial levels and periodontal status of patients wearing fixed and removable orthodontic retainers

INTRODUCTION

The purpose of this study was to compare and evaluate salivary microbial levels and periodontal status in patients using a fixed lingual retainer, a removable vacuum-formed retainer, or a Hawley retainer after orthodontic treatment with fixed appliances.

METHODS

Forty-five patients who finished their orthodontic treatment with fixed appliances and were about to start the retention phase were randomly divided into the following 3 groups of 15 individuals each: the fixed lingual retainer group, the vacuum-formed retainer group, and the Hawley retainer group. Periodontal measurements, such as the plaque index, gingival index, probing depth, and bleeding on probing, were obtained at the following 4 time points: at debonding (T0) and 1 week (T1), 5 weeks (T2), and 13 weeks (T3) after debonding. Saliva samples were collected 3 times in total: at T0, T2, and T3. A quantitative analysis for Streptococcus mutans and Lactobacillus casei was performed with the use of real-time polymerase chain reaction. The Kruskal-Wallis test and 1-way analysis of variance were used for the statistical comparisons of the groups.

RESULTS

No statistically significant difference in salivary S mutans and L casei levels was found among the 3 groups (P >0.05). They showed no statistically significant differences in plaque index, gingival index, bleeding on probing, and probing depth values (P >0.05). All periodontal parameters showed statistically significant decreases from T0 to T3 in all 3 groups (P <0.001). The S mutans and L casei levels were decreased significantly from T2 to T3 in the lingual retainer and Hawley retainer groups, whereas they decreased significantly from T0 to T3 in the vacuum-formed retainer group.

CONCLUSIONS

Fixed and removable orthodontic retainers do not differ in salivary S mutans and L casei levels and periodontal status. With all retainers, regardless of whether they are fixed or removable, oral hygiene improved after orthodontic treatment with fixed appliances.

Effects of probiotics on salivary Streptecoccus mutans and Lactobacillus levels in orthodontic patients

INTRODUCTION

In this study, we aimed to determine the effect of regular probiotic consumption on microbial colonization in saliva in orthodontic patients and to comparatively evaluate the difference between the systemic consumption of probiotic products and the local application.

METHODS

This study included 3 groups with 15 orthodontic patients in each. The control group included patients who had no probiotic treatment, the subjects in the kefir group consumed 2 × 100 ml of kefir (Atatürk Orman Ciftligi, Ankara, Turkey) per day, and the subjects in the toothpaste group brushed their teeth with toothpaste with probiotic content (GD toothpaste; Dental Asia Manufacturing, Shah Alam, Selangor, Malaysia) twice a day. Samples were collected at 3 times: beginning of the study, 3 weeks later, and 6 weeks later. The salivary flow rate, buffer capacity, and Streptococcus mutans and Lactobacillus levels in the saliva were evaluated. Chair-side kits were used to determine the S mutans and Lactobacillus levels.

RESULTS

A statistically significant decrease was observed in the salivary S mutans and Lactobacillus levels in the kefir and toothpaste groups compared with the control group (P <0.05). A statistically significant increase was observed in the toothpaste group compared with the control and kefir groups in buffer capacity. Changes in the salivary flow rate were not statistically significant.

CONCLUSIONS

The regular use of probiotics during fixed orthodontic treatment reduces the S mutans and Lactobacillus levels in the saliva.

Caries risk assessment. A systematic review

OBJECTIVE

To assess the ability of multivariate models and single factors to correctly identify future caries development in pre-school children and schoolchildren/adolescents.

STUDY DESIGN

A systematic literature search for relevant papers was conducted with pre-determined inclusion criteria. Abstracts and full-text articles were assessed independently by two reviewers. The quality of studies was graded according to the QUADAS tool. The quality of evidence of models and single predictors was assessed using the GRADE approach.

RESULTS

Ninety original articles fulfilled the inclusion criteria. Seven studies had high quality, 35 moderate and the rest poor quality. The accuracy of multivariate models was higher for pre-school children than for schoolchildren/adolescents. However, the models had seldom been validated in independent populations, making their accuracy uncertain. Of the single predictors, baseline caries experience had moderate/good accuracy in pre-school children and limited accuracy in schoolchildren/adolescents. The period of highest risk for caries incidence in permanent teeth was the first few years after tooth eruption. In general, the quality of evidence was limited.

CONCLUSIONS

Multivariate models and baseline caries prevalence performed better in pre-school children than in schoolchildren/adolescents. Baseline caries prevalence was the most accurate single predictor in all age groups. The heterogeneity of populations, models, outcome criteria, measures and reporting hampered the synthesis of results. There is a great need to standardize study design, outcome measures and reporting of data in studies on caries risk assessment. The accuracy of prediction models should be validated in at least one independent population.

Susceptibility to dental caries and the salivary proline-rich proteins

Early childhood caries affects 28% of children aged 2–6 in the US and is not decreasing. There is a well-recognized need to identify susceptible children at birth. Caries-free adults neutralize bacterial acids in dental biofilms better than adults with severe caries. Saliva contains acidic and basic proline-rich proteins (PRPs) which attach to oral streptococci. The PRPs are encoded within a small region of chromosome 12. An acidic PRP allele (Db) protects Caucasian children from caries but is more common in African Americans. Some basic PRP allelic phenotypes have a three-fold greater frequency in caries-free adults than in those with severe caries. Early childhood caries may associate with an absence of certain basic PRP alleles which bind oral streptococci, neutralize biofilm acids, and are in linkage disequilibrium with Db in Caucasians. The encoding of basic PRP alleles is updated and a new technology for genotyping them is described.

Acidic proline-rich protein Db and caries in young children

Polymorphic, acidic proline-rich proteins (PRPs) in saliva influence the attachment of bacteria associated with caries. Our aims were to detect one of three acidic PRP alleles of the PRH1 locus (Db) using polymerase chain-reaction (PCR) on genomic DNA, and to determine its association with caries. DNA was obtained from buccal swabs from Caucasian and African-American children, and their caries experience was recorded. PCR primers designed around exon 3 of the PRH1 locus gave a 416-base product representing Db and a 353-base product representing the other two alleles (Pa or Pif). In Caucasians, Db gene frequency was 14%, similar to Db protein from parotid saliva. In African-Americans, however, it was 37%, 18% lower than Db from parotid saliva (reported previously). Compared with African-Americans, all Caucasians had significantly greater Streptococcus mutans colonization, but only Db-negative Caucasians had significantly more caries. Alleles linked to Db may explain racial differences in caries experience.

Salivary mutans streptococci counts as indicators in caries risk assessment in 6–7-year-old Chinese children

OBJECTIVES

This study aimed to determine whether salivary mutans streptococci (MS) counts in Chinese children had any value in the prediction of new caries in the permanent dentition in the age interval of 6.5-8.5 years.

METHODS

Four hundred and thirty-three 6-7-year-old children participated in this 2-year longitudinal study. Salivary MS counts were obtained at baseline with the spatula method. Dentin and enamel caries was recorded at baseline and at the follow-up, 2 years later. Spearman's correlation coefficients were computed. Past caries experience variables at baseline were entered into a multiple regression model with caries increment of the permanent dentition as dependent variable. MS counts were subsequently entered into the model to assess the additional caries predictive value.

RESULTS

Spearman's correlation coefficient for MS counts and caries experience of the primary dentition at baseline was 0.48 and for MS counts and caries increment in the permanent dentition 0.12. In the multiple regression model caries increment of the permanent dentition had an adjusted R2 of 0.17 when the past caries experience variables were entered. Adding MS counts in the regression model did not change the R2 value.

CONCLUSIONS

Salivary MS counts did not add any caries predictive value when past caries experience variables were used as caries predictors in this Chinese child population.

HLA class II alleles and salivary numbers of mutans streptococci and lactobacilli among young adults in Japan

To investigate the genetic predisposition toward the accumulation of oral microorganisms, the association between the alleles of HLA-DQA1, -DQB1 and -DRB1 and the salivary numbers of mutans streptococci and lactobacilli were examined in 102 young adults in Japan. HLA-DQA1*0102, DQB1*0604, DRB1*0802, and DRB1*1302 were weakly associated with the numbers of lactobacilli in saliva samples (P<0.05). HLA-DQB1*0601 was associated with the salivary numbers of mutans streptococci (P<0.01). Two HLA class II haplotypes, HLA-[DRB1*0802-DQA1*0301-DQB1*0302] and HLA-[DRB1*1302-DQA1*0102-DQB1*0604], were also weakly associated with the salivary numbers of lactobacilli (P<0.05). These observations suggest that HLA class II alleles may be related to the salivary populations of oral microorganisms, such as mutans streptococci and lactobacilli.

The value of salivary bacterial counts as a supplement to past caries experience as caries predictor in children

This study aimed to determine whether salivary mutans streptococci and lactobacilli counts could add any value to a combination of caries experience variables that was recently presented for the prediction of caries. Sixty-nine children at the age of 7.5 yr participated in this longitudinal study. Microbiological data were obtained at the ages of 7.5, 9.5 and 11.5 yr and caries data at the ages of 7.5. 9.5. 11.5, 13.5 and 15.5 yr. Spearman's correlation coefficients were computed, and forward multiple regression analyses were carried out using bacterial counts and caries experience parameters as explanatory variables and caries increment as a dependent variable. The explained variance (adjusted R2 value) was the measure used to assess the additional value of bacterial counts to the caries predictive potential of the combined parameters of the past caries experience. Correlation coefficients between bacterial counts and 4-yr caries increment were from 0.22 tip to 0.54. In all cases, the simultaneous streptococcus mutans-lactobacilli counts showed a statistically non-significant additional adjusted R2 value of <0.06. The results do not lend support to the concept that these salivary bacterial counts are useful additional caries predictors for the mixed dentition, when a combination of caries experience parameters is used.

Salivary mutans streptococci and caries development in the primary and mixed dentitions of children

OBJECTIVES

For more than 25 years, both cross-sectional and longitudinal studies of dental caries have focused on the role of salivary mutans streptococci (SMS) as a predictor of caries risk. This study examined the relationship between SMS and longitudinal caries development in the primary and mixed dentitions.

METHODS

Eighty-five children, initial mean age 3.8 years, were examined for dental caries at baseline and once annually for 6 years. Children's SMS were sampled with a tongue blade, which was impressed onto plates containing a medium selective for SMS. After incubation, colony forming units of SMS were determined semi-quantitatively and categorized as low, moderate or high.

RESULTS

Children classified as high caries risk at baseline had significantly greater (P<0.05) dmfs scores for all teeth, and in the primary molars, than children classified as moderate or low caries risk at every age but 9 (P<0.10). Children classified as high risk at age 3 had the greatest DMFS increment through age 8. Based on annual examinations, there was a trend towards increasing mean dmfs/DMFS scores among children classified as high risk in every year.

CONCLUSIONS

The current study is among the first to report on the ability of annual measurements of SMS to identify long-term caries risk in both the primary and the mixed dentitions. Despite limitations in predicting caries risk using microbiological methods, this longitudinal study supports the overall benefits of this type of testing.

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.

Xylitol in caries prevention: what is the evidence for clinical efficacy?

Xylitol has attracted much attention as an alternative sweetener. Essentially all clinical studies concerning the effect of xylitol on caries development consent to its non-cariogenicity and to the beneficial effect of substituting sucrose with xylitol in chewing gums and sweets. However, claims of anti-caries or therapeutic effects, and superiority of xylitol over other polyols are still to be confirmed by well designed and conducted studies from independent research groups.

Concepts of dental caries and their consequences for understanding the disease

The way in which we conceptually consider dental caries determines our choice of preventive and treatment strategy. In this paper the definition of dental caries is discussed and the related problems concerning causality are addressed. Dental caries reflects symptoms of ongoing and past disease--not the disease itself. As such, it is important to record early stages of signs of the disease, i.e. non-cavitated stages of lesion development. The dynamic nature of the processes leading to net loss of mineral (hence a lesion) is emphasized, and appreciating that caries is ubiquitous in populations around the world and initiation and progression of lesions continues lifelong leads to the logical conclusion that we can control dental caries through a variety of measures--but not truly prevent the disease. We can prevent cavities by controlling the patho-physiological events which may result in a net loss of mineral. The relative role of dental plaque in caries control is discussed in relation to the role of the many determinants which influence the likelihood for lesion development. It is concluded that several paradigms about the nature of dental caries should be reconsidered to provide the most cost-effective dental services.

Number of mutans streptococci or lactobacilli in a total dental plaque sample does not explain the variation in caries better than the numbers in stimulated whole saliva

For practical reasons the numbers of mutans streptococci (MS) and lactobacilli (LB) in plaque are commonly estimated from saliva samples. The saliva counts are considered to be a reasonable indicator of the entire dentition's total microbial load. However, the value of salivary counts for explaining and predicting caries have been found to be low. There was therefore reason to compare the relationships between caries on the one hand and, on the other, the number of MS or LB in plaque and in saliva, respectively, in order to assess their relative merits for explaining the variation in caries, both in a total material and in subgroups with less favourable oral hygiene. Sixty children aged 14-15 years participated in the study. Caries and plaque were registered and the number of MS and LB was estimated in total plaque and in stimulated saliva samples. The results showed that the number of MS or LB in plaque did not explain the variation in caries to a greater degree than did the salivary counts. For both bacteria the explanatory values increased, as expected, in subgroups with less favourable oral hygiene, but not even at this higher level of explanation was there any difference between plaque and saliva. The LB count was a stronger explanatory variable than the MS count. It was concluded that the number of MS and LB, estimated in total plaque as well as in saliva samples, is not a useful tool in prediction.

Inconsistent levels of mutans streptococci and lactobacilli measured in stimulated whole saliva

The counts of mutans streptococci (MS) and lactobacilli (LB) in saliva have been used for prediction of dental caries. The results have not justified putting the methods into clinical practice as the explanatory values of the bacteria for caries are low. There is therefore reason to question how representative the methods for sampling and estimation of those bacteria are. The aims of this study were to investigate if the variation in caries is better explained by the bacteria, estimated as means of numbers in double saliva samples, than by numbers in single samples, and to determine whether chewing on either the preferred or the non-preferred side influences the bacterial counts. Twenty-five healthy subjects were included in the study. Two saliva samples were collected with a 1-wk interval by chewing on a piece of sterile paraffin wax on the preferred side only. One month later this was repeated on the opposite side. In order to test if there were variations in the numbers of bacteria due to the laboratory methods, a paired cultivation of 20 samples was carried out. The results showed that the coefficients of variation (c.v.) for the differences between the individual double samples varied between 110 and 276% of the total mean of the double samples. The paired cultivation gave r values for MS of 0.93 and for LB of 0.99. Using double samples did not increase the explanatory values for caries. There were higher explanatory values for caries on the preferred side than on the non-preferred side, this being much more pronounced for lactobacilli than for mutans streptococci.

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)

Variation of posterior approximal caries incidence with consumption of sweets with regard to other caries-related factors in 15-18-year-olds

The aim of this study was to analyze the relationships between caries incidence and a number of caries-related factors in 15-18-yr-olds, in order to estimate the explanatory value of consumption of sweets under different conditions. Sixty-nine 18-yr-olds were interviewed about consumption of sweets and other sugar-containing products during the past 3 yr. Data on oral hygiene, salivary counts of mutans streptococci and lactobacilli, salivary flow rate and oral sugar clearance time were collected when the individuals were 15 and 18 yr old. Caries incidence for the 3-yr period was expressed as a percentage of the number of caries-free approximal surfaces of premolars and molars at the age of 15. Simple linear correlations between caries incidence and the different variables showed that lactobacilli count ranked first (r = 0.26), sweets second (r = 0.25), and mutans streptococci count third (r = 0.24). The r value for caries incidence and consumption of sweets increased in subgroups with combinations of poor oral hygiene, a high intake of other sugary products and a low salivary flow rate (r = 0.67-0.70). In conclusion, consumption of sweets should still be considered an important caries-related factor and particularly harmful when oral hygiene is poor and consumption of other sugary products is high.

Correlations between caries prevalence and potential etiologic factors in large samples of 4-5-yr-old children

A data base containing information on dental caries, oral hygiene, gingival state, Streptococcus mutans and lactobacillus counts, and salivary flow rate and buffer capacity in some 2800 4-5-yr-old South African children was created in 1984. The children were equally distributed in four groups; rural black, urban black, urban Indian, and urban white. In this study, the data were used for simple linear correlations between all the factors including caries as well as stepwise multiple regression analyses between caries prevalence and the independent factors in each of the four groups. The highest r value obtained in the single correlations was 0.56 for dmfs/lactobacillus count in the white group. The overall pattern of the groups did not vary much. In the stepwise multiple regression analyses, lactobacilli entered first in all groups. S. mutans and oral hygiene interchanged as Nos. 2 and 3, and gingival state or buffer capacity came out as No. 4. The highest percentage of caries variability explained by these regressions was 25%, in the urban black group, while the lowest was 12%, in the indian group. It was concluded that our generally accepted etiologic factors are unsatisfactory to explain variation in caries in observational studies, which among other things might be ascribed to the inadequate way these factors generally are measured or estimated.

Caries experience, periodontal treatment needs, salivary pH, and Streptococcus mutans counts in a preadolescent Down syndrome population

The prevalence of dental caries and periodontal treatment needs in an institutionalized population with Down syndrome was examined and the relationship between caries prevalence, salivary pH, and salivary levels of Streptococcus mutans was studied. Thirty-two children with Down syndrome, aged 8 to 13, were compared with two control groups of similar age ranges: healthy children and non-Down mentally retarded (MR) children living in the same institution as the Down syndrome population. The gender ratio mixtures in each group also matched the study sample. Caries experience as indicated by decayed, missing, and filled surfaces (DMF-S) showed significantly lower mean scores for the Down syndrome group compared with both control groups. A similar pattern was found when evaluating the mean numbers of decayed surfaces. Streptococcus mutans counts, expressed as number of colony-forming units on mitis salivarius agar plates among the Down syndrome group, were the lowest, although not statistically significant compared with the counts of the healthy children. Both groups had bacterial counts which were significantly lower than those of the MR group. Significant differences between the two institutionalized groups and the healthy group were recorded for the salivary pH levels. The periodontal treatment needs as evaluated by the Community Periodontal Index of Treatment Needs showed significant difference between the MR group versus both the healthy population and the Down syndrome group. On the whole, 84% of the Down syndrome children were cariesfree.

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.