Effects of types of toothpastes (whitening versus regular) and brands of silicone aesthetic ligatures on discoloration of elastomeric ligatures applied to mandibular central and lateral incisors: a hierarchical, single-blind, 6-arm, split-mouth randomized clinical trial.

OBJECTIVE: Both orthodontists and patients frequently express concerns about the discolorations of elastomeric ligatures. It is important to know which toothpastes or brands or other factors can severely discolor elastic ligatures. Despite the clinical importance of this matter, the literature in this regard is very scarce (only 3 studies) with contradicting results. Therefore, the aim of this study was to evaluate the impact of whitening and regular toothpastes on the color stability of clear elastomeric ligatures from different brands, applied to different incisors. METHODS: In this hierarchical 6-arm split-mouth double-blind randomized clinical trial, 264 ligatures were applied to orthodontic brackets bonded to bilateral mandibular central and lateral incisors in 66 patients: The sample was randomized twice: Once it was randomly divided into three groups of toothpastes (n = 66 patients): Regular Crest, Advance White Arm & Hammer Whitening, and Extra Whitening Crest. The next phase was split-mouth: In each patient, one side of the mouth was randomly assigned to Ortho Organizer brand while the other side was assigned to Ortho Technology ligatures. In the baseline, the ligatures were evaluated using the CIE L*a*b color system. After four weeks, the ligatures were re-evaluated using the CIE L*a*b* color system. The extents of changes in color parameters L, A, B, and E were analyzed using 3-way repeated-measures ANOVA. Other statistical analyses were also conducted using repeated-measures ANOVA, Pearson correlation coefficient, and independent-samples t-test (alpha = 0.05). RESULTS: The overall color stability of elastic ligatures was not influenced by the toothpastes in use (P = 0.649 for ∆E, P values ranging between 0.669 and 0.989 for other parameters) or the type of incisor on which the ligature was mounted (P = 0.656 for ∆E, P values ranging between 0.006 and 0.647 for other parameters). The discolorations of elastic ligatures were significantly different between the two ligature brands (P = 0.000 for ∆E, P values = 0.000 for other parameters). Ortho Organizer showed a higher color stability than Ortho Technology. Both ligature brands showed a level of discoloration deemed clinically unacceptable (E > 3.3), regardless of the toothpaste used. Discolorations were mostly due to severe changes in ∆B parameter (yellowness) compared to ∆L or ∆A (P = 0.000). CONCLUSION: Although the type of toothpaste has no significant impact on the color stability of elastomeric ligatures, the brand of ligatures individually plays a significant role in this regard. TRIAL REGISTRATION: The study was prospectively registered with the Iranian Registry of Clinical Trials on March 28, 2022 (IRCT Code: IRCT20220315054292N1) before beginning the study.