Contamination of Low Frictional Elastomeric Ligatures by Streptococcus mutans: A Prospective RT-PCR and AFM Study

To compare Streptococcus mutans colonization between low-friction elastomeric ligatures and to correlate microbial colonization levels with the surface roughness status. The study included 160 premolars of 10 patients. During the study period, which consisted of 4 sessions each lasting 4 weeks, the ligature types Slide™ Low-Friction Ligature (Leone, Firenze, Italy), Tough-O Energy™ (Rocky Mountain Orthodontics, Denver, USA), and Sili Ties™ (Dentsply Sirona, Surrey KT13 0NY, UK), and steel ligatures (American Orthodontics, Sheboygan, USA) as a control, were fixed to the premolar teeth by clockwise rotation among the jaw quadrants. The plaque index (PI) and gingival index (GI) were obtained before bonding (T0), 6 weeks after bonding (T1), and subsequently every 4 weeks (T2, T3, T4). Presence of S. mutans was analyzed by real-time polymerase chain reaction at T1, T2, T3, T4. Surface roughness was evaluated with Atomic Force Microscopy (AFM) before ligation (Ra0) and after (Ra1) ligation. The paired t-test, ANOVA, repeated measures of ANOVA, and the Kruskal-Wallis test were used for the statistical analysis. S. mutans colonization was significantly higher on the Slide group (P < .05). The lowest Ra0 was seen in Slide and the highest was seen in the Tough-O Energy group. There was no correlation between S. mutans colonization and Ra1 parameters of elastomeric groups (P > .05). S. mutans colonization showed variations in low-friction elastomeric ligatures independent of surface roughness. Ringshaped low-friction elastomeric ligatures were not different from the steel ligature in terms of S. mutans colonization.