Forces produced by different nonconventional bracket or ligature systems during alignment of apically displaced teeth

Objective: To analyze the forces released by four types of passive stainless steel self-ligating brackets (SLBs), and by two nonconventional elastomeric ligature-bracket systems when compared with conventional elastomeric ligatures on conventional stainless steel brackets during the alignment of apically displaced teeth at the maxillary arch. Materials and Methods: An experimental model consisting of five brackets was used to assess the forces released by the seven different ligature-bracket systems with 0.012" or 0.014" super- elastic nickel titanium wire in the presence of different amounts of apical displacement of the canine (ranging from 1.5 mm to 6 mm). Comparisons between the different types of bracket/wire/ ligature systems were carried out by means of ANOVA on ranks with Dunnett's post hoc test (P < .05). Results: When correction of a misalignment greater than 3 mm is attempted, a noticeable amount of force for alignment is generated by passive SLBs and nonconventional elastomeric ligature- bracket systems, and a null amount of force is released in the presence of conventional elasto- meric ligatures on conventional brackets. Conclusions: When minimal apical displacement is needed (1.5 mm), the differences in performance between low-friction and conventional systems are minimal. These differences become significant when correction of a misalignment of greater than 3.0 mm is attempted. © 2009 by The EH Angle Education and Research Foundation, Inc.