Dimensional accuracy of ceramic self-ligating brackets and estimates of theoretical torsional play

Objective: To ascertain the dimensional accuracies of some commonly used ceramic self-ligation brackets and the amount of torsional play in various bracket-archwire combinations. Materials and Methods: Four types of 0.022-inch slot ceramic self-ligating brackets (upper right central incisor), three types of 0.018-inch ceramic self-ligating brackets (upper right central incisor), and three types of rectangular archwires (0.016 × 0.022-inch beta-Titanium [TMA] (Ormco, Orange, Calif), 0.016 × 0.022-inch stainless steel [SS] (Ortho Technology, Tampa, Fla), and 0.019 × 0.025-inch SS (Ortho Technology)) were measured using a stereomicroscope to determine slot widths and wire cross-sectional dimensions. The mean acquired dimensions of the brackets and wires were applied to an equation devised by Meling to estimate torsional play angle (γ). Results: In all bracket systems, the slot tops were significantly wider than the slot bases (P <.001), yielding a divergent slot profile. Clarity-SLs (3M Unitek, Monrovia, Calif) showed the greatest divergence among the 0.022-inch brackets, and Clippy-Cs (Tomy, Futaba, Fukushima, Japan) among the 0.018-inch brackets. The Damon Clear (Ormco) bracket had the smallest dimensional error (0.542%), whereas the 0.022-inch Empower Clear (American Orthodontics, Sheboygan, Wis) bracket had the largest (3.585%). Conclusions: The largest amount of theoretical play is observed using the Empower Clear (American Orthodontics) 0.022-inch bracket combined with the 0.016 3 0.022-inch TMA wire (Ormco), whereas the least amount occurs using the 0.018 Clippy-C (Tomy) combined with 0.016 3 0.022-inch SS wire (Ortho Technology).