Streptococcus mutans and total bacteria levels quantification in saliva and occlusal plaque. Universal bacterial specific (Eub1, Eub2) and the S. mutans specific (gtfB, glucosyltransferase B) primers were used to evaluate the level of total bacteria and S. mutans in using qPCR. Percentage of total bacteria (A) and S. mutans(B), within the total bacteria, in the saliva and occlusal plaque collected from subjects with (FOA,) and without fixed orthodontic appliances (Control,). The groups differences significance was analyzed with one-way ANOVA followed by Kruskal–Wallis multiple comparisons test; ∗P < 0.01, ∗∗P < 0.001, ∗∗∗P < 0.0001.