The dimensional accuracy of orthodontic brackets slots is extremely important, since inaccuracy can affect orthodontic mechanics. The aim of this study was to investigate the slot heights of Roth prescription brackets from several commercial manufacturers. A total of 360 maxillary and mandibular incisor brackets from 6 different commercial models (Kirium Line, Ovation, Roth Light, Synthesis, Integra, and Miniature Twin) were selected and divided into 18 experimental groups containing maxillary central incisor, maxillary lateral incisor, or mandibular central incisor brackets (n = 20). Brackets were viewed under a scanning electron microscope to acquire a clear image of all slot edges, and slot heights were measured at 2 locations on each bracket to acquire mean values. Group means and standard deviations were calculated and compared with the manufacturer reference value of 0.5588 mm (0.0220 inch) plus or minus a tolerance level of 0.0100 mm (∼0.0004 inch). With the exception of Synthesis maxillary lateral incisor brackets (P = 0.230), all brackets had slot heights that were significantly smaller than 0.5588 mm (P < 0.05). The measured slot heights were 1.84% to 14.91% smaller than the reference value. Virtually all measured bracket slot heights were smaller than claimed by the manufacturers, with great variability within the same brand and indication, revealing a lack of precision in the fabrication process.
Keywords: dimensional accuracy; orthodontic appliances; orthodontic brackets; orthodontic wires; orthodontics.