Effects of a ceramic active self‑ligating bracket on retraction/tipping/ rotation of canine, premolar mesialization, and transverse arch dimensions: A preliminary single‑blind split‑mouth randomized clinical trial

Abstract

Background: There is no clinical study on ceramic self‑ligating brackets (SLBs). Therefore, this
preliminary study was conducted for the first time to address its effects.
Materials and Methods: This split‑mouth randomized trial was performed on 32 quadrants in
16 orthodontic patients needing extraction of maxillary premolars and distalization of canines.
In each blinded patient, right/left sides were randomized into control (ceramic bracket) and
experimental (ceramic SLB) groups. Dental stone models were taken before canine retraction
and 3 months into retraction. Models were digitized as three‑dimensional models. Changes were
measured on superimposed models. Groups were compared using Wilcoxon signed‑rank test
(α = 0.05, β = 0.1).
Results: Both bracket types caused significant changes after 3 months in terms of all assessed
clinical outcomes (P ≤ 0.002). Compared to conventional ceramic brackets (control), ceramic SLBs
reduced retraction rate (P = 0.001), canine rotation (P = 0.001), canine tipping (P = 0.002), and
arch expansion at the canine site (P = 0.003). However, the extents of anchorage loss (P = 0.796)
and arch constriction in the premolar area (P = 0.605) were not statistically different between the
bracket types.
Conclusion: Compared to conventional metal‑lined ceramic brackets, active ceramic SLB
can increase the duration of canine distalization, while reducing canine rotation and tipping
(inducing more bodily movements). The loss of anchorage with ceramic SLB was similar to that
of conventional ceramic bracket after 3 months of treatment (considering the lower rate of SLB
canine retraction during that time). Both brackets similarly constricted the arch at the premolar
site. In the canine area, they expanded the arch, with the SLB causing smaller extents of expansion.
Key Words: Corrective orthodontics, bodily tooth movement, tooth rotation