Propylthiouracil (PROP)--a tool to determine taster status in relation to caries experience, streptococcus mutans levels and dietary preferences in children

PURPOSE: Dental caries remains the single most common disease of childhood that is neither self-limiting nor amenable to short term pharmacological management. Hence, there is a need to identify and institute preventive measures for those children who are at a greater risk for developing dental caries to determine the prevalence of tasters and non tasters among the group of school aged children. To compare and contrast the prevalence of dental caries, S. mutans levels and dietary preferences in children with different genetic sensitivity levels to the bitter taste of PROP. METHOD: A total no of 500 children belonging to the age group of 6-12 years of both sexes were recruited from A.B. Shetty Memorial Institute of Dental Sciences in Mangalore, India. PROP sensitivity test was carried out to determine the inherent genetic ability to taste a bitter or sweet substance. Estimation of Streptococcus mutans levels were done, a questionnaire was given to evaluate their dietary habits and the caries experience was recorded Collected data were tabulated and subjected for statistical analysis using Pearson Chi - square test of significance. RESULTS: The results suggested that there was increase in the caries experience and S. mutans levels among the group of non tasters as compared to tasters. Tasters tended to be sweet dislikers and non tasters tended to be sweet likers. On the whole tasters had a healthier dentition as compared to non tasters. CONCLUSION: The PROP test proved to be a useful tool in determining the genetic sensitivity levels of bitter taste. Knowledge of an individuals taste perception can help us in identifying the children who are at higher risk for dental caries.     

Genetic sensitivity to the bitter taste of 6-n propylthiouracil: a new risk determinant for dental caries in children

The aims of the present study were to contrast the prevalence of dental caries in children with different genetic sensitivity levels to the bitter taste of 6-n-propylthiouracil (PROP) and to determine the taste quality and taste intensity preferences of food products among the taster and nontaster groups. Overall caries experience (dmfs/DMFS) was significantly higher for nontasters than tasters. Caries experience on the available surfaces (dfs/DFS) was found to be significantly higher in nontasters than in medium tasters and in medium tasters than in supertasters (r=-0.41, P < 0.001). Majority of the nontasters were sweet likers and preferred strong tasting food products, while majority of the supertasters were sweet dislikers and preferred weak tastes. There was a significant increase in the overall caries experience in the population, as the genetic ability to detect PROP taste decreased ( P < 0.001). After all associated factors (age, gender, race, number of teeth and OHI-S) were controlled; multiple linear regression analyses revealed that taste was the only variable significantly related to overall caries experience.     

Caries experience in 15‐year‐old school children in Bangalore with inherited taste sensitivity levels to 6‐n‐propylthiouracil: an observational study

Aim: The relationship between sugar consumption and caries has been researched extensively for many years. The individual drive for the consumption of sweet food is controlled by a variety of biologic, psychologic, and sociologic factors. Sweet preference has been linked to bitter taste sensitivity to 6‐n‐propylthiouracil, a heritable trait. The present study investigates the association between inherited taste sensitivity to 6‐n‐popylthiouracil and dental caries experience in 15‐year‐old school children. Methods: Two hundred 15‐year‐old school children from randomly selected schools in Bangalore, India, participated in the study. Data were collected regarding demographic factors and socioeconomic status by personal interviews with the children. Sensitivity to 6‐n‐propylthiouracil was determined using Tepper filter paper method, and the responses were recorded on the labeled magnitude scale. Each child was examined thoroughly for oral hygiene status and caries experience. Appropriate statistical tests, such as chi‐squared test, Fisher’s exact test, and Kruskal–Wallis test, were used to analyze the data. Results: Non‐tasters were significantly associated with caries experience (P < 0.001). The decayed component in non‐tasters (3.43 ± 2.18) was statistically significant when compared to tasters (2.86 ± 1.58 medium tasters, 1.50 ± 0.55 supertasters). Conclusions: After all associated factors were controlled, 6‐n‐propylthiouracil taste status was the only independent variable significantly related to overall caries experience.     

Caries experience in children with various genetic sensitivity levels to the bitter taste of 6-n-propylthiouracil (PROP): a pilot study

PURPOSE: The objective of this pilot study was to determine the prevalence of coronal dental caries among children with different genetic sensitivity levels of taste, as determined by 6-n-propylthiouracil (PROP). METHODS: Coronal caries and restorations in permanent and primary dentition were evaluated in 150 healthy school-aged children aged 6 to 12 years. A filter paper containing 6-n-propylthiouracil was used to determine each subject's genetic ability to taste bitter and sweet substances. Supertasters perceived stronger tastes from a variety of bitter and sweet substances than both medium tasters and nontasters. The data were analyzed by ANOVA with Duncan's multiple range test, Mantel-Haenszel chi-square, multiple linear regression analyses, and Pearson's coefficient of correlation. RESULTS: The nontasters had more mean decayed, missing, and filled surfaces (dfs/DMFS) than tasters. The values of mean decayed and filled surfaces of primary dentition and mean decayed, missing, and filled surfaces of permanent dentition (dfs/DMFS) and mean decayed surfaces of primary dentition and permanent dentition (ds/DS) were significantly higher in nontasters than in medium tasters, and in medium tasters compared with supertasters. After adjusting for missing teeth, the data were expressed as a percentage of the available surfaces, and the significant differences in dfs/DMFS and ds/DS persisted (r = -0.49, P < .001 and r = -0.51, P < .0001 respectively). CONCLUSIONS: After all associated factors were controlled, taste was the only independent variable significantly related to overall caries experience. The results of this study suggested an increased prevalence of overall caries experience in nontaster children.     

The relation between 6-n-propylthiouracil sensitivity and caries activity in schoolchildren

Caries activity tests are being used to assess caries risk in children. In recent years the purpose of most studies has been to develop practical, quick, reliable and economic tests. Clinical studies showed that the difference in sensitivity to the bitter taste of 6-n-propylthiouracil (PROP) is a heritable trait and may influence children's nutritional habits and caries development. The aim of this study was to investigate the relation between PROP sensitivity and caries activity in schoolchildren, in comparison with different caries activity tests. One hundred and twenty children aged between 7 and 12 years (mean age 9.97 ± 1.59) were investigated to determine socioeconomic status and oral hygiene habits, fluoride consumption, DMFT, DMFS, df, dfs, plaque indexes, and nutritional habits. Children were divided into three groups according to their caries risk status based on the Cariogram. The solution test and the PROP-impregnated filter paper test were used together to determine PROP sensitivity. After all associated factors had been controlled, stepwise regression analyses revealed that DMFT and dfs scores were important determinants of PROP. According to dfs, the sensitivity of the Cariogram and of PROP tests was 0.85 and 0.70, respectively, and specificity was 0.32 and 0.33, respectively. There was an inverse significant relationship between PROP sensitivity and DMFT, DMFS, and dfs results (p < 0.01). In conclusion, PROP nontasters were significantly more likely to have high caries risk than PROP tasters (p < 0.01).     

Role of taste perception in white spot lesion formation during orthodontic treatment

Objectives:To investigate the role of individual''s taste sensitivity using 6-n-propylthiouracil (PROP) in the development of white spot lesions (WSLs) in adolescent orthodontic patients.Materials and Methods:44 healthy adolescents, aged 12 to 16 years old, who were in fixed-appliance orthodontic treatment for at least 6 months, consented to participate in this cross-sectional study. Data regarding participants'' demographic information, oral hygiene practices, and dietary habits were obtained by a questionnaire. An oral clinical examination was performed to determine the oral hygiene status, the presence of WSLs and dental caries experience. The taste phenotype of the participants was evaluated through PROP test and they were accordingly divided into PROP nontasters and PROP tasters.Results:The sample consisted of 24 subjects in the WSL group and 20 subjects in the WSL-free group. The WSL group demonstrated higher mean plaque score (48.2), mean decayed, missing, and filled surfaces (2.38), and mean decayed, missing, and filled teeth (1.96) scores compared to the WSL-free group (38.7, 0.85, and 0.55, respectively), but no significant differences were found. Most subjects in the WSL group were PROP nontasters (66.6%) whereas most subjects in the WSL-free group were PROP tasters (75%); a significant difference was observed between the groups (P = .006).Conclusions:The prevalence of white spot lesions was significantly higher in adolescent orthodontic patients who were PROP nontasters compared to PROP tasters. A PROP taste perception could be a potential risk factor for the formation of WSLs during fixed orthodontic treatment that warrants further attention.     

The relationship between phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) taster status and taste thresholds for sucrose and quinine

OBJECTIVE: The aim of this study was to investigate the relationship of taster status with taste detection and recognition thresholds for sucrose and quinine. DESIGN: Sixty-nine subjects (35 men and 34 women; mean age, 23.9+/-1.2 years) were included. Stimulus fluids were prepared, one each for phenylthiocarbamide (PTC), 6-n-propylthiouracil (PROP), sucrose and quinine HCl. In each series, successive solutions, which comprised a total of 15 grades, differed by 0.25log units of the molar concentration. Two concentrations of NaCl (0.32 and 1.0 M) were prepared. The subjects were classified as nontasters and tasters using their PTC and PROP perceptions. Tasters were classified as medium-tasters and supertasters by the ratio of perceived bitterness of above-threshold PROP relative to the perceived saltiness of NaCl (PROP ratio). Taste detection and recognition thresholds for sucrose and quinine were determined by standard two-alternative forced choice trials. A Student's t-test, a Pearson's correlation analysis and linear contrasts in a one-way analysis of variance (ANOVA) were used. RESULTS: The percentages of nontaster, medium-taster and supertaster were 13, 70 and 17%, respectively. There were no significant gender differences in the taste detection and recognition thresholds for sucrose and quinine. The threshold for PTC and PROP showed significant correlations with taste threshold for quinine. Linear contrast in one-way ANOVA showed that the greater the value of PROP ratio, the more sensitive to sweet and bitter tastes (p<0.001). CONCLUSION: The PTC and PROP taster status is closely related with taste detection and recognition thresholds for sucrose and quinine.     

Caries prevalence and some caries related factors for 12 year-old children from Vientiane and Luang Prabang provinces in Lao People's Democratic Republic.

Caries prevalence and some caries related factors for 100 twelve-year-old children from Vientiane and Luang Prabang provinces in Lao People's Democratic Republic were studied. The caries prevalence was high showing a DMFT of 4.6 with 9% of the children being caries free, the D comportment contributed mostly to the DMFT and the Significant Caries Index (Sic Index) was DMFT 8.0. As to the caries related factors, 25% of the children were in the high mutans class, 31% of the group had high or very high Lactobacilli scores and 84-88% studied took local sweet snacks, chips and sweet drinks every day. Taking into consideration the high caries prevalence, the mutans streptococci distribution, the frequent intake of sweets and also the relatively low fluoride concentration in the drinking waters, oral health preventive programmes are indicated to prevent a possible caries epidemic in Laos in the future.     

Clinical, salivary, and bacterial markers for caries risk assessment in schoolchildren: a 4-year follow-up

Background.  In Mexico, there is a high prevalence of dental caries and large groups of children still show extensive untreated dental damage.
Aim.  This study aims to evaluate, in a cohort of 6-year-old Mexican children, the relationship between caries increment at 4 years and the following caries risk markers: fissure morphology, caries experience, salivary flow rate, Snyder test results, and mutans and lactobacilli counts.
Design.  To predict new caries lesions in 110 schoolchildren, clinical, salivary, and bacteriological caries risk markers were used, including fissure morphology, caries experience, salivary flow rate, Snyder test, and Streptococcus mutans and lactobacilli counts. To determine the validity of these markers, the baseline data were compared with the caries increment after 4 years.
Results.  The risk model's capacity to predict caries was moderate (specificity 79.6% and sensitivity 78.6%). Caries experience ( P  = 0.0001), Snyder test ( P  = 0.002), and fissure morphology ( P  = 0.024) had the strongest association with caries increment. Salivary flow rate, lactobacilli, and S. mutans counts did not contribute significantly to the prediction of caries lesions in these children.
Conclusion.  In addition to the initial caries experience, tooth morphology and Snyder test proved to be useful predictors for caries. These three risk markers may be particularly useful in targeting caries prevention efforts in developing countries.     

Effect of mixed mutans streptococci colonization on caries development

OBJECTIVE: To evaluate the clinical importance of mixed mutans streptococci colonization in predicting caries in preschool children. METHODS: Caries prevalence was examined twice, with a 6-month interval, in 410 preschool children aged 3-4 years at baseline. A commercial strip method was used to evaluate the mutans streptococci score in plaque collected from eight selected interdental spaces and in saliva. Mutans streptococci typing polymerase chain reaction (PCR) assays (Streptococcus sobrinus and Streptococcus mutans, including serotypes c, e, and f) were performed using colonies on the strips as template. RESULTS: Twenty variables were examined in a univariate analysis to predict caries development: questionnaire variables, results of clinical examination, mutans streptococci scores, and PCR detection of S. sobrinus and S. mutans (including serotypes c, e, and f). Sixteen variables showed statistically significant associations (P < 0.04) in the univariate analysis. However, when entered into a logistic regression, only five variables remained significant (P < 0.05): caries experience at baseline; mixed colonization of S. sobrinus and S. mutans including S. mutans serotypes; high plaque mutans streptococci score; habitual use of sweet drinks; and nonuse of fluoride toothpaste. CONCLUSION: 'Mixed mutans streptococci colonization' is a novel measure correlated with caries development in their primary dentition.     

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

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

年轻恒牙患龋预测快速法试验研究

目的了解用快速检测菌斑的方法预测3～5年后儿童龋病的发生情况的准确性。方法采用菌斑显示剂（2％品红）测定73位4—5岁儿童的牙面菌斑，根据菌斑多少及当前患龋情况（dmfs）两项指标来预测其3～5年后龋病发生情况，并与用当前患龋情况（dmfs）、唾液变链计数及唾液缓冲能力3项指标联合预测3-5年后龋病发生情况进行比较。结果用这两种方式进行预测的敏感性、特异性及预测可信度均差异无统计学意义（P〉0．05）。结论提示在大规模普查筛选龋高危儿童时可选用检测菌斑和乳牙患龋情况两项指标这一快速预测龋病的方法。     

Antimicrobial effect of fluoride mouthrinse on mutans streptococci and lactobacilli in saliva

PURPOSE: This study was designed to determine whether the long-term use of fluoride mouthrinse affects the salivary levels of mutans streptococci and lactobacilli. METHODS: The subjects consisted of 414 school children aged 7, 10, and 12 yrs. Among these subjects, 243 children had received fluoride mouthrinse since 5 years of age at nursery schools, and comprised the "mouthrinse group." The remaining 171 children, the "no mouthrinse group," had not received fluoride mouthrinse. All of the children received routine dental health education. The levels of mutans streptococci and lactobacilli for the subjects in both groups were measured using Dentocult SM Strip mutans and Dentocult LB Dip Slide, respectively. Dental examinations were conducted to obtain data on caries prevalence (dfs and DMFS). Logistic regression analysis was used to control confounding factors: age, dfs, DMFS, frequency of toothbrushing, sum of permanent tooth surfaces sealed, frequency of sweet snacks, frequency of sweet drinks, and the use of fluoridated toothpaste. RESULTS: There was a significant difference in mean DMFS between the mouthrinse group and no mouthrinse group at all ages. Children with fluoride mouthrinse had lower levels of mutans streptococci, and there was a significant association between the experience of fluoride mouthrinse and the score of Dentocult SM strip Odds ratio: 0.64, P < 0.05. However, there was no significant relation between the experience of fluoride mouthrinse and the score of Dentocult LB Dip Slide. The results of this study demonstrated that the long-term use of fluoride mouthrinse affected the detectable levels of mutans streptococci, but did not affect the levels of lactobacilli. CONCLUSIONS: These results suggest that fluoride mouthrinse might contribute to reducing the number of mutans streptococci.     

Trends in paediatric dental caries by poverty status in the United States, 1988–1994 and 1999–2004

International Journal of Paediatric Dentistry 2010; 20: 132–143 Background. Recent reports have suggested that dental caries among some young children is increasing in the United States. Aim. To describe changes in paediatric caries prevalence by poverty status in the United States. Design. National Health and Nutrition Examination Survey (NHANES) data for children aged 2–11 years for 1988–1994 and 1999–2004 were used. Results. Caries in the primary dentition increased among poor and non‐poor boys aged 2–8 years (45–53% and 23–31%, respectively) and among non‐poor boys aged 2–5 years (13–21%) from 1988–1994 to 1999–2004. Caries experience also increased on buccal‐lingual, mesio‐distal, and occlusal primary dental surfaces among poor children aged 2–8 years and this increase may be attributed to an increase in the number of dental surfaces restored. In the mixed dentition, caries remains relatively unchanged. Caries continues to decline in the permanent dentition for many children, but is increasing among poor non‐Hispanic whites aged 6–8 years (8–22%) and poor Mexican‐Americans aged 9–11 years (38–55%). Conclusions. For many older children, caries continues to decline or remain unchanged. Nevertheless, for a subgroup of younger children, caries is increasing and this increase is impacting some traditionally low‐risk groups of children.     

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%.     

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

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

Social and behavioural indicators of caries experience in 5-year-old children

Abstract The aim of this study was to investigate the relative influence of socio-economic status and behaviour on dental health of 5-yr-old children. Dental data from a representative sample of 5-yr-old children from Lothian, Scotland, were analysed in combination with reported behavioural data collected by standardised telephone interviews of the mothers. Dental data was established for 520 children. A total of 324 mothers of these children were interviewed giving a response rate in relation to the original sample frame of 62.3%. Caries experience increased with both decreasing toothbrushing behaviour and a more manual occupational status. The relationship between the parent's occupation and the child's dental health was almost two times as large as the relationship between reported toothbrushing behaviour and the child's dental health. Caries experience increased with both increasing sweet consumption and a more manual occupational status. The relationship between the parent's occupation and the child's dental health was almost four times as large as the relationship between reported sweet consumption and the child's dental health. In conclusion, dental health in 5-yr-old children is related to parent's occupation and toothbrushing and sweet consumption. Occupational status is a much stronger factor than behaviours as reported by mothers.     

Relationship of microbial and salivary parameters with dental caries in Brazilian pre-school children

Caries examination and collection of paraffin wax-stimulated saliva samples were performed in 37 children, 3-6 years old, in a child-care facility at the Vidigal slum, Rio de Janeiro, Brazil. The levels of mutans streptococci and lactobacilli in saliva were estimated by the Cariescreen and by the Dentocult tests and the saliva secretion rate was determined. Statistical analysis was performed on surface-based and patient-based caries prevalence rates (SBCPR and PBCPR), and related to bacterial and salivary parameters. The results show that 31 of the 37 children were caries active. The SBCPR for the primary dentition was 6.7% +/- 1.0%. Occlusal surfaces were the most affected by decay. Regression analysis revealed that mutans streptococci salivary levels were significantly associated with the SBCPR (P = 0.0001). Similarly, lactobacilli salivary levels were significantly associated with the SBCPR (P = 0.0001). No significant association could be found between the saliva secretion rate and the SBCPR. When regression analysis was used to model dependence of the SBCPR on both organisms, the mutans streptococci and lactobacilli salivary levels were significantly associated with the SBCPRs (P = 0.0021 and 0.0118, respectively), and salivary levels of these organisms accounted for 57% of the SBCPR variability. These findings indicate that the levels of mutans streptococci and lactobacilli in saliva are significantly related to the SBCPRs on the primary dentition of these children.     

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

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

Relationships between socioeconomic backgrounds, caries associated microflora and caries experience in 12-year-olds in Bosnia and Herzegovina in 2004

AIM: To present the prevalence of dental caries in Bosnia and Herzegovina (BH), to estimate the levels of salivary mutans streptococci and lactobacilli and compare them with caries prevalence in 12-years-old children from different socioeconomic backgrounds. STUDY DESIGN AND METHODS: A survey was carried out in 8 cantons of the Federation of BH (FBH) and in Republic Srpska (RS) in 2004. The final sample included 560 12-year-olds. The clinical examinations focused on dental status, expressed as DMFT index, and they were carried out by one examiner, following WHO standard methodologies. Additionally, the study involved 109 12-years old children from Sarajevo, divided in three groups, based on their socioeconomic background. For measuring lactobacillus and mutans streptococci (MS) count in saliva Dentocult LB and Dentocult SM-Strip Mutans were used. Levels of MS and lactobacilli were expressed as a score between 0 and 3, indicating very low to very high levels of SM and lactobacilli. RESULTS: The average DMFT of the 12-year-olds was 4.16+/-2.92. On average, 91% of the 12-year-olds were affected with dental caries. The SiC Index was 7.41+/-3.31. Investigating the relationship between caries associated microflora and caries experience in children of different socioeconomic status showed the following: significant difference in caries prevalence was found in children with different living conditions, where children with high socioeconomic status had better oral health compared to the other two groups. For mutans streptococci, 25.7% of the children had mutans class 0, 24.8% class 1, 34.9% class 2 and 14.6% class 3. The mean DMFT for mutans class 0 was 3.50, for class 1 was 4.30, for class 2 was 5.62 and for class 3 was 6.0. For lactobacilli, 38.5% of the children had lactobacilli class 0, 25.7% class 1, 23.9% class 2 and 11.9% class 3. The mean DMFT for lactobacilli class 0 was 4.3, for class 1 was 4.9, for class 2 was 4.8 and for class 3 was 6.0. No significant differences in the level of mutans streptococci and lactobacilli were found between the groups. CONCLUSION: There is moderate caries prevalence among BH 12-year-olds (DMFT 4.16+/-2.92). Caries experience varies between children with different living condition but no relation between levels of salivary mutans streptococci and lactobacilli and socioeconomic status of children could be found.