The Relationship Between Carious Risk And The Qualitative Detection Of Streptococcus Mutans And Lactobacilli Of Dental Caries In Children

In most parts of the world, dental caries is still a major public health problem. However, dental caries not only cause personal illness, but also produce amazing waste. The traditional treatment to dental caries is to detect the disease, and then remove the cares to make restoration. In recent years, with a better understanding of dental caries process, the treatment methods have changed:fluoride and remineralization of prevention strategies are popular, unless caries has decayed the dental hard tissue; otherwise, the traditional treatment method is not desirable. Treatment of clinical decision-making is based on caries risk assessment. Caries risk assessment is an important component of caries management, which is divided into two aspects of the risk factors and its future development. A comprehensive caries assessment should include:past history and present history of dental caries, dietary factors, fluoride exposure, cariogenic microorganisms, saliva testing, general history, host factors, behavioral and physical factors, the possible impact of drugs and social factors. Science-based caries risk assessment and prevention of caries occurrence of dental caries high-risk population is an effective means to reduce the incidence of caries. Although dental caries is widely distributed in the general population, not in the average trend,80%of which occur in45%of children in epidemiological surveys of caries high-risk population."High risk" populations should more frequently go to the dentist, increasing screening frequency. Only through effective screening and prevention, the incidence of dental caries can be successfully prevented. Among many caries risk factors, Detection and identification of cariogenic bacteria in the mouth is of great significance for the assessment of caries activity, as well as large-scale epidemiological survey.Objective:①Based on epidemiological investigation, the children are grouped according to WHO standard and ICDAS standards to study the effect of these two standards and their clinical significance.②To detect Streptococcus mutans and Lactobacillus acidophilus by polymerase chain reaction (PCR) method and analysis the relationship between these two kinds of cariogenic bacteria and caries risk by statistical method. Methods:Oral epidemiological survey of dental caries in Tianjin primary school.25children of8to10-year-old were extracted in every group according to the results of caries-free (DMFS=0), medium caries (DMFS4to6) and high caries (DMFS>8) by WHO standard. No caries group collect plaque on smooth surface of permanent teeth, caries group collect plaque in pit and fissure, frozen in the laboratory refrigerator. The total DNA of mixed plaque was extracted, to do16S-rDNA sequence specific PCR amplification for detection and identification of Streptococcus mutans and Lactobacillus acidophilus in the sample. SPSS software for data processing, multiple independent samples rank sum test and chi-square test was applied for statistical analysis.Results:Based on WHO standard, in the caries-free (DMFS=0) group, Streptococcus mutans and Lactobacillus acidophilus jointly negative rate is52%(13), P<0.05; in medium caries (DMFS4-6) groups, Streptococcus mutans and Lactobacillus acidophilus jointly positive rate was48%(12), P<0.05; in high caries (DMFS>8) group, Streptococcus mutans and Lactobacillus acidophilus jointly positive rate was60%(15), P<0.05; Moreover, jointly positive rate of Streptococcus mutans and Lactobacillus acidophilus in medium caries group and high caries group was54%(27), P<0.05.Based on CDAS-II standards, Streptococcus mutans and Lactobacillus acidophilus in caries group jointly positive detection rate is44.6%(29), P＜0.05.Using Fisher exact chi-square test, epidemiological data of75samples is statistically significant according to WHO standard and ICDAS standards. Streptococcus mutans and Lactobacillus acidophilus jointly positive rate of caries group was significantly higher than that of caries-free group (P<0.05) and Streptococcus mutans and Lactobacillus acidophilus jointly negative rate of caries-free group was significantly higher than that of caries group (P<0.05) based on WHO standard; Streptococcus mutans and Lactobacillus acidophilus jointly positive rate of caries group was signiticantly higher than that of caries-free group (P<0.05) and Streptococcus mutans and Lactobacillus acidophilus jointly negative rate of caries-free group was signiticantly higher than that of caries group (P<0.05) based on ICDAS standards. The caries-free group divided by WHO standard regrouped by ICDAS standards, there is no statistical significance of Streptococcus mutans and Lactobacillus acidophilus positive rate (P>0.05).Conclusion:1Based on WHO standards and ICDAS standards, Streptococcus mutans and Lactobacillus acidophilus of children’s dental plaque can be used as indicators for caries risk assessment.2. Compared with the WHO standard, ICDAS standard for the classification of dental caries process may be more refined, showing higher sensitivity in the caries prevention, however, WHO criteria may be more instructive in clinical treatment.3. Streptococcus mutans and Lactobacillus acidophilus may be more meaningful for the prevention of dental caries and caries risk assessment than other cariogenic bacteria.4. Compared with one single cariogenic bacteria, a multiply of cariogenic bacteria can be more accurate for assessment of caries disease.