Regina Célia Rocha Peres

Relationship among microbiological composition and presence of dental plaque, sugar exposure, social factors and different stages of early childhood caries

OBJECTIVE This cross-sectional study aimed to investigate the relationship among microbiological composition of dental plaque, sugar exposure and social factors, as well as the presence of visible plaque in preschoolers with different stages of early childhood caries. DESIGN A total of 169 children were clinically examined according to the World Health Organisation criteria + early caries lesions and were divided into three groups: caries-free (n=53), early caries lesions-ECL (n=56), and cavitated caries lesions-CCL (n=60). The presence of clinically visible dental plaque on maxillary incisors was recorded. After that, dental plaque from all buccal and lingual smooth surfaces was collected and the number of colony-forming units of mutans streptococci and total microorganism, as well as the presence of lactobacilli was determined. Daily frequency of meals containing sugar was assessed by a diet chart whereas social factors were evaluated by a questionnaire. The data were analysed by chi-square test followed by multiple logistic regressions (alpha=0.05, confidence interval=95%). RESULTS High levels of mutans streptococci (OR=2.28), high total sugar exposure (OR=5.45) and presence of dental plaque (OR=2.60) showed significant association with ECL (p<0.05). High total microorganism count (OR=5.18), high solid sugar exposure (OR=2.50) and the presence of lactobacilli (OR=24.99) revealed significant association with CCL (p<0.05). CONCLUSIONS These results support the conclusion that dietary sugar experience influenced the microbiological composition of dental plaque. Moreover, the early stage of caries is highly affected by mutans streptococci and visible dental plaque on maxillary incisors whereas cavities are strongly related to lactobacilli and total microorganism.

Association between polymorphism in the promoter region (G/C-915) of PAX9 gene and third molar agenesis

Purpose: Hypodontia is the congenital absence of one or more (up to six) permanent and/or deciduous teeth, being one of the most common alterations of the human dentition. Genetic polymorphisms are variations of DNA sequences occurring in a population. This study investigated whether G-915C single nucleotide polymorphism (SNPs) in the PAX9 gene promoter is associated with hypodontia in humans. Material and Methods: The polymorphism in region G/C-915 of PAX9 gene (NCBI ref SNP ID: rs 2073247) of 240 patients was analyzed, being 110 controls and 130 individuals with third molar agenesis. After DNA extraction, the region of interest was amplified by PCR technique using two different primers. The significance of the differences in observed frequencies of polymorphisms in both groups was assessed by odds-ratio and chi-squared test with 95% confidence interval. Results: Genotype CC was more frequent in patients with agenesis (11.5%) compared to the control (1.8%), while GG was more prevalent in the control group (39.1%) compared to the individuals with agenesis (26.2%). Conclusion: These data showed that the allele C could be associated with the third molar agenesis.

Relationship among Salivary Carbonic Anhydrase VI Activity and Flow Rate, Biofilm pH and Caries in Primary Dentition

This study aimed to determine the activity of carbonic anhydrase isoenzyme VI (CAVI) in the saliva of preschool children with caries and to investigate the relationship between caries and salivary CAVI activity, salivary flow rate and biofilm pH before and after a 20% sucrose rinse. Thirty preschool children aged 45.3–80.3 months were divided into two groups: a caries-free group and a caries group. Clinical examinations were conducted by one examiner (ĸ = 0.95) according to WHO criteria (dmfs) and early caries lesions. From each subject, CAVI activity, salivary flow rate and plaque pH were determined before and after a sucrose rinse. The results were submitted to Wilcoxon, Mann-Whitney and Spearman correlation tests (α = 0.05). The results showed that prerinse CAVI activity and its variation were higher in the saliva from caries children than from caries-free children. No difference was found between the two groups in postrinse salivary CAVI activity. After rinsing, biofilm pH differences were lower in both groups (p = 0.0012 and p = 0.0037 for the caries and caries-free groups, respectively). Also, after the sucrose rinse, salivary flow rate significantly increased in caries and caries-free groups (p = 0.0003, p = 0.0037). The variation of salivary CAVI activity was negatively correlated with caries (r = –0.501, p = 0.005). Child’s age showed a positive correlation with caries (r = 0.456, p = 0.011). These results suggest that variation of salivary CAVI activity and child’s age are associated with dental caries in preschool children.

Analysis of MMP-9 and TIMP-2 gene promoter polymorphisms in individuals with hypodontia

Hypodontia, the congenital absence of one or a few teeth, is one of the most common developmental alterations of human dentition. It may cause masticatory and speech dysfunctions and create esthetic problems with orthodontic and prosthetic implications. MMP-9 is an important member of the matrix metalloproteinase (MMP) family that participates in remodeling of extracellular matrix during tooth development. A C-to-T base exchange at position -1562 creates two different alleles, and the CT and TT genotypes promote high activity of the MMP-9 gene promoter. Tissue inhibitor of metalloproteinase-2 (TIMP-2) regulates the activity of MMPs in the extracellular matrix and is co-expressed with gelatinases A (MMP-2) and B (MMP-9) during mouse tooth morphogenesis. A polymorphism in the TIMP-2 gene promoter at position -418 has been found in a Sp-1 binding site. In this study, the association between these DNA polymorphisms and hypodontia has been investigated. The significance of differences in frequencies of polymorphisms in control and test groups was assessed by Chi-square test (p<0.05). Data suggested that MMP-9 gene promoter polymorphism was not associated with hypodontia. The high frequency of GG genotype in the TIMP-2 gene promoter showed that this site was unsuitable for studies of DNA polymorphism-disease associations in the studied population.

Assessment of cavitated and active non-cavitated caries lesions in 3- to 4-year-old preschool children: a field study.

BACKGROUND The prevalence of early childhood caries (ECC) is high in developing countries; thus, sensitive methods for the early diagnosis of ECC are of prime importance to implement the appropriate preventive measures. AIM To investigate the effects of the addition of early caries lesions (ECL) into WHO threshold caries detection methods on the prevalence of caries in primary teeth and the epidemiological profile of the studied population. DESIGN In total, 351 3- to 4-year-old preschoolers participated in this cross-sectional study. Clinical exams were conducted by one calibrated examiner using WHO and WHO + ECL criteria. During the exams, a mirror, a ball-ended probe, gauze, and an artificial light were used. The data were analysed by Wilcoxon and Mc-Nemars tests (α=0.05). RESULTS Good intra-examiner Kappa values at tooth/surface levels were obtained for WHO and WHO+ECL criteria (0.93/0.87 and 0.75/0.78, respectively). The dmfs scores were significantly higher (P<0.05) when WHO+ECL criteria were used. ECLs were the predominant caries lesions in the majority of teeth. CONCLUSIONS The results strongly suggest that the WHO+ECL diagnosis method could be used to identify ECL in young children under field conditions, increasing the prevalence and classification of caries activity and providing valuable information for the early establishment of preventive measures.

Relationships between occlusal or free-smooth and approximal caries in mixed dentition

This cross-sectional study aimed to examine the relationships between free-smooth or occlusal surfaces and approximal caries in 104 schoolchildren between 6 and 8 years of age. Caries diagnosis was clinically and radiographically assessed, and white spot lesions, evident caries lesions or restorations, as well as radiolucence in enamel were considered to be caries. In the studied subjects, the correlations were analyzed in the 1st primary molars (Ds), the 2nd primary molars (Es), the 1st permanent molars (6s), and all molars. The data were statistically analyzed by chi-square test. Significant correlations between occlusal surface caries and approximal surface lesions were observed in Ds and Es teeth and in all molars, but not for 1st permanent molars. For free-smooth surface, these correlations were significant only for Es and all molars. Sensitivity and specificity for occlusal surface as an indicator of approximal caries in the same tooth type ranged from 73% to 83% and 51% to 58%, respectively. Similarly, for free-smooth surface the values varied from 22% to 60% and 57% to 90%, respectively. Sensitivity and specificity for occlusal surface caries in identifying subjects with approximal caries were 78% and 70%, respectively; for free-smooth surface, the corresponding values were 59% and 65%, respectively. The results suggest that visually detected caries lesions are indicative of approximal caries. Thus, if a certain risk limit is defined and the corresponding number of caries lesions in different surfaces is reached, the risk is above the threshold and could be a practical guideline on the need for radiography in this age group of patients with “moderate caries experience”.

Absence of association between transforming growth factor-beta1 promoter polymorphisms and hypodontia.

Hypodontia, the congenital absence of one or a few teeth, is one of the most common alterations of the human dentition. The most common permanent missing teeth are the third molars, second premolars, and maxillary lateral incisors. Although hypodontia does not represent a serious public health problem, it may cause masticatory and speech dysfunctions and esthetic problems. Transforming growth factor-beta1 (TGF-beta1) is believed to play an important role in tooth development. Its gene is expressed at bud, cap, and bell stages of odontogenesis. Genetic polymorphisms in the TGF-beta1 gene promoter were shown to interfere with the transcriptional activity of this gene. To further investigate the role of the TGF-beta1 gene in human hypodontia, we analyzed the frequencies of the -509 polymorphism (C-T) alleles and -800 polymorphism (G-A) alleles and genotypes in the TGF-beta1 gene promoter in 51 Caucasian subjects with hypodontia and 48 control individuals. Our data suggest that these TGF-beta1 promoter polymorphisms are not associated with hypodontia.