Precision of indirect bonding of lingual brackets using the Quick Modul System (QMS)®

Almost all common laboratory procedures for lingual orthodontic appliances use indirect bonding of brackets via transfer trays. Ensuring precise transfer of these bracket positions to the oral cavity is especially important, as subsequent manual adjustments are challenging in lingual orthodontics and even minor errors of bracket placement may result in considerably deviating tooth positions. The purpose of this study was to evaluate in vivo the precision of indirect bonding of lingual brackets using the "Quick Modul System" (QMS®; Halbich Lingualtechnik, Berlin, Germany).

The study included eight consecutive patients treated with lingual brackets. After placing the brackets on a setup cast, the resultant positions were digitized with an optical scanner (OraScanner®; OraMetrix, Richardson, TX, USA). Individual transfer copings (QMS®) were used to transfer the brackets to the mouth, followed by intraoral scanning and virtual superimposition to analyze how much the intraoral bracket positions deviated from the positions on the cast.

Translational deviations added up to a mean transfer error of 0.12 mm in the mesiodistal, 0.13 mm in the orovestibular, and 0.10 mm in the vertical planes. Mean deviations in rotational directions amounted to 2.20° of inclination, 3.21° of angulation, and 2.29° of rotation.

The transfer system investigated in this study is capable of transferring bracket positions with good clinical precision. No differences between the bracket types and both modifications of the transfer copings were noted.