Positioning of Brackets
Successful treatment with the preadjusted appliance requires precise bracket placement in all three planes of space.
There are numerous suggestions in the literature that can be used as a guide for vertical positioning of brackets on teeth. Most authors use the distance between the incisal edge and the bracket slot as a reference. We recommend the values indicated in Table 6.1 . There will be a difference between the incisal edge of the central and lateral incisors of approximately 0.5 mm when using these values ( Fig. 6.2 ).
In our own studies, we compared the congruence between the bracket base and individual tooth surfaces ( Fig. 6.3 ). Scanning the labial surfaces of 500 maxillary central incisors made it possible to develop an average three-dimensional labial tooth surface, which was then compared with bracket bases supplied by various manufacturers in the mesiodistal and occlusogingival directions.
A good fit of the bracket base is essential, as the bracket slot of a poorly fitting bracket will not be positioned accurately to achieve the desired tooth movement. This is often why teeth sometimes express unwanted movement, which is usually corrected toward the end of the treatment, using artistic bends.