Detection of S. mutans and spapAgtf in Dental Plaque

Objective: To analyse the relationship between caries and S. mutans along with its poisonous factors by detecting their percentage. Method: Probes were designed and tested. Dental plaques were diluted and spreaded onto BHI and TYCSB cultures. Numbers of S. mutans and all bacteria were automatic counted by gel imaging system. Percentage of S. mutans and gtfAspap in all bacteria were examined with flow cytometer. According to standard line for gtf amplification, the copy numbers of gtf in dental plaques were counted. Results: Spap and gtf probes were binded specifically to S. mutans. There was 59% and 51% respectively for caries and caries-free dental plaques, without statistically significant (P=0.19). There were 49% and 32% respectively for caries and caries-free. The average order of spap in caries and careis-free is 15.14 and 5.13. The average order of gtf in caries and careis-free is 14.93 and 5.50. The percentage of poisonous factors was significantly higher than that of caries-free (P<0.05). The detection rate of S. mutans was 76%in caries and 47% in caries-free. The proportion of S. mutans was statistically higher in caries than in caries-free (P=0.04). The average order of the copy numbers of gtf was 29.70 in caries, while in caries-free, the average order was 17.35, which was significantly lower than that former one (P=0.04). Conclusion: The probes designed according to spap and gtf genes were feasible for detection of S. mutans with satisfying sensitivity and specificity. The percentage of the poisonous positive bacteria were significantly higher in caries than in caries-free volunteers. We could provide the experiment guidance for the caries risk prediction by analyzing of the percentage of S. mutans and its poisonous factors (spap and gtf) in dental plaque. Therefore, in large-scale epidemic investigatation, they could save time and increase sensitivity.