Effect of the bracket types on microbial colonization and periodontal status

Objective: To evaluate the effect of different bracket types on the levels of Streptococcus mutans (SM) and Lactobacillus (LB) in saliva, in plaque, and on the periodontal condition. Materials and Methods: Forty patients aged 14 to 16 years, who had Angle Class I malocclusion with minimal crowding, were nonsmokers, were without systematic disease, and did not use antibiotics or oral mouth rinses during the 3-month period before the study were randomly selected. The patients were subdivided into two groups with random allocation of bracket type: conventional brackets (CB; Avex Mx, OPAL orth.) with steel wire ligature or self-ligating brackets (SLB; F1000, Leone S.p.A.). Microbial and periodontal records were obtained before bonding (T-1) and 1 month after bonding (T-2). Microbial samples were collected from the stimulated saliva and the plaque from the labial surfaces of the upper and lower lateral incisors. To estimate the number of colony-forming units of SM and LB, Dentocult SM and LB kits were used. The plaque index (PI), gingival index (GI), and pocket depth (PD) values were recorded to evaluate the periodontal condition. Paired t-test and Mann-Whitney U-test were used to compare the groups statistically. Results: No significant differences occurred in SM or LB colonization between the groups. In the SLB group, PI, GI, and PD values increased significantly (P<.05). A greater increase was found in PD value in the SLB group (0.98 mm) compared with the CB group (0.04 mm; P<.05). Conclusions: The F1000 SLB do not have an advantage over Avex Mx CB with respect to periodontal status and colonization of SM and LB.