Treatment NOTE
NOTE
Self-ligating brackets do not confer any advantage during the bonding procedure. Time savings could potentially be made using indirect bonding techniques and/or with self-etching primers.
Even an experienced operator may find it challenging to complete an archwire change in both upper and lower arches in less than 9 minutes, the basic value established by health insurance companies in Germany for reimbursement to dentists (BEMA).
Ligation of Archwires A number of manufacturers claim that less chairside time is required for removing and ligating archwires. We are not aware of any study that confirms this. A direct comparison between self-ligation and standard brackets showed similar times for both methods.5 However, it is important to remember that changing the elastomeric modules has to be undertaken by an experienced operator. There may be one other potential advantage with selfligating systems: the operator can open and close the selfligating brackets easily without any assistance. For efficient and speedy archwire changes using conventional elastomeric modules, it is best to have an assistant handing the modules to the operator. Another advantage may be that self-ligating brackets usually ensure full engagement of the wire, as the locking mechanisms would otherwise not shut properly. This can be important if wire changes are done by less experienced operators who have yet to learn how to spot partially disengaged wires. It is also worthwhile mentioning that not all bracketarchwire combinations are advisable or indeed possible.6 The Damon system, for example, works with a rigid locking mechanism. This can make it difficult to ligate thicker rectangular wires, and occasionally it is difficult to open or close the clip. The manufacturer recommends specific archwire sequences to avoid these potential issues (Fig. 3.40). The same also applies for 3 M’s SLBs. For example, it is not possible to engage a 0.017 × 0.025 Turbo-NiTi (Ormco) in a SmartClip or Clarity SL bracket (Fig. 3.41). In general, it is uncomfortable for patients who are being treated with these brackets to use wires that are larger than 0.021 × 0.021 (NiTi or stainless steel). A shorter procedure time with SLBs is only evident in comparison with ligating an entire arch using steel ligatures.7
Another important aspect of the treatment is often not mentioned by the manufacturers—i.e., the possibility of using elastomeric chains. There are significant differences between self-ligating bracket systems in this respect. Some systems do not even allow silicone or elastomeric chains to be used under or over the archwire. Bracket systems with a very rounded design may make it very challenging for elastic chains to be used at all (Fig. 3.42). Elastomeric chains interfere with the locking mechanism of some self-ligating systems. This applies in particular to the Discovery SL bracket (Dentaurum), the Time 2 and Time 3 brackets (American Orthodontics), and the Flare bracket (Adenta). Other self-ligating brackets make it difficult, if not impossible, to ligate silicone elastomeric chains on top of the archwire. The Speed bracket, for example, has no retention for attaching a chain on top of the archwire. Some composite-based materials with poor abrasion characteristics (e.g., Damon 3) may lose their capacity to engage an elastomeric chain (Fig. 3.43). Removing the archwires can also be difficult in patients with significant calculus accumulation, which is often more pronounced in adult patients. Passive brackets (such as Damon) can be particularly difficult to open and close (Fig. 3.44) in such cases. Some manufacturers recommend using vinegar or 37% phosphoric acid to overcome the blockage of the system. “Airflow” and “sandblasting” have also been recommended. Any of the above methods would certainly eliminate any potential advantages of self-ligation over conventional ligation.
Fig. 3.40 Failure to engage a braided 0.017 × 0.025 Turbo-NiTi into a Clarity SL bracket.
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