The key to success is not the TSAD alone

I read with great interest the systematic review of Fudalej and Antoszewska, who evaluated the effectiveness of orthodontic distalizers reinforced with temporary skeletal anchorage devices (TSADs). Unfortunately, the authors did not consider the biomechanical heterogeneity of different distalizers with TSADs. The key to success is not the use of TSADs, but the force direction from them. Only if the force vector lies in the level of the center of resistance of the tooth, bodily molar distalization (no tipping of the molar) can be achieved. Bony anchorage of distalizers with miniscrews alone will then prevent unwanted effects in terms of mesial movement and tipping of the canines and the first and second premolars, and proclination of the incisors.

The implication that anchorage loss would reduce the force on the molars is puzzling, since the appliance is presumably continuously reactivated. Furthermore, the implication that end-of-treatment outcomes or stability has anything to do with the use of TSADs is irritating. TSADs are simply a means of reliable anchorage during treatment.

Placement of TSADs in the proximity of roots carries the risk of damaging the roots or periodontal structures. The use of acrylic buttons is associated with hygiene problems and increases the risk of inflammation of the underlying soft tissues.

Assigning TSAD appliances to Class II treatment in general, for example, has no merit, since these appliances are designed for pure tooth movement (use of functional appliances might be indicated in some patients). The correct diagnosis remains paramount and is more important than the anchorage of treatment devices, which are just a means to an end.

A distinction should be made between noncompliance distalization appliances anchored with TSADs in the bony palate alone and appliances anchored with more than 1 anchorage method on neighboring structures (palatal endosseous, dental, periodontal). The latter are associated with more or less anchorage loss. However, unwanted effects on the molars during distalization are not avoided by the TSAD per se, but by biomechanically optimized distalizing appliances connected to it. The modern approach to appliance design should thus focus on simplification of the construction and the connection of the appliance to the TSAD.

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Apr 11, 2017 | Posted by in Orthodontics | Comments Off on The key to success is not the TSAD alone
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