Seo KW, Kwon SY, Kim KA, Park KH, Kim SH, Ahn HW, Nelson G

Displacement pattern of anterior segment using combined antero-posterior lingual retractor combined with a palatal plate.

- Korean J Orthod 2015 Nov;45:289-98.

I thank the authors for this interesting article and hope to ask their further clarifications in following areas.

Q1. Compared with the C-lingual retractor group, the antero-posterior lingual retractor groups showed more intrusive effects on the anterior teeth during the retraction period. Certainly, it is desirable if a gummy smile is on the problem list. However, in more common situations of absence of the anterior vertical excess, how can one control the vertical level of the anterior teeth with the antero-posterior lingual retractor appliance?

Q2. What could be the merits of using the anteroposterior lingual retractor over the conventional lingual brackets?

Q3. To distalize or intrude the posterior teeth, what kinds of modifications do you recommend on the antero-posterior lingual retractor appliance?

Q4. Considering the action and reaction force in the law of physics, the intrusive force in the anterior region should be associated with the extrusive force in the posterior. Yet, the results showed that the vertical positions of the posterior teeth were well-maintained. How can you explain this result?