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References

Mirzakouchaki B Asymmetrical O-ring ligation. J Clin Orthod. 2008; 42
Tying twin brackets. 2000. https://doi.org/10.1067/mod.2000.104446

Tricks of the Trade: Derotation of severely rotated lower incisors with fixed appliances

From Volume 14, Issue 2, April 2021 | Page 109

Authors

Catherine A Brierley

BDS(Hons), MFDS RCS, MClinDent, Orthodontic, Post-CCST

Sheffield and Chesterfield, Chesterfield, Derbyshire, UK

Articles by Catherine A Brierley

Article

The difficulty, particularly with rotated lower incisors, is that there is very little span between the brackets to allow full engagement of the wire into the slot (Figure 1). Partial ligation means that the clinician has to tediously and continuously retie until the tooth derotates sufficiently to allow full ligation. Severely rotated lower incisors, especially when the patient is being treated on a non-extraction basis, can delay the progression from the initial aligning archwire. There are several techniques that have been employed including:

  • Using a light nickel–titanium (NiTi) wire such as an 0.012” NiTi. This usually requires several visits of retying, and clinicians would usually need to place a second round, wider-diameter NiTi wire before being able to progress to a rectangular NiTi.
  • Module configurations. (1) Placing an elastomeric module in a figure-of-eight configuration; (2) asymmetrical O-ring ligation;1 or (3) using a short metal ligature. These methods rely on having sufficient span between the brackets to allow full ligation of the wire into the slot.
  • Circumferential ligation.2
  • Using powerchain in a force couple. This can be an effective technique, but must be employed carefully to ensure that the incisor is not moved out of bone.
  • Coil spring ties or a rotation wedge. These are likely to be plaque retentive.
  • Space creation with push coil for the rotated tooth following by ‘piggy-back’ mechanics to align the rotated incisor.
  • Using self-ligating brackets. This method can help to establish full ligation of teeth that are moderately rotated and have sufficient space between the brackets for the archwire to be deflected into the slot.

    • Figure 1. (a, b) The mesial tie wings are too intimately associated to allow full archwire ligation, even when a short metal ligature is employed.
    Figure 2. The simple 2D lingual appliance in situ.
    Figure 3. (a, b) After 6 weeks, the teeth are derotated sufficiently to allow full labial archwire ligation.

    A useful technique to derotate lower incisors, where the mesial tie wings are too closely approximated to allow full archwire engagement, involves use of a 2D lingual appliance. These appliances are low profile. There is a simple gate that can be opened with a flat plastic to create the slot into which the archwire can be placed. There is no specific armamentarium required, apart from the brackets themselves. Molar tube holders can be used to place the brackets, and Weingart pliers to close the gates. A sectional archwire is placed (usually an 0.014” NiTi), which allows for sufficient derotation, to then place the labial archwire fully engaged in 6–8 weeks' time. The patients do not usually mind having a very short course of lingual appliance treatment, and the costs of the appliance are offset by the reduction in chairside time and time in the aligning archwire sequence.