396 Readers' forum

that the tongue could be a major factor in somemalocclusions.

John MewLondon, United Kingdom

Am J Orthod Dentofacial Orthop 2012;141:395-60889-5406/$36.00Copyright � 2012 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2012.02.008

Questioning treatment strategies inhyperdivergent patients

It was fascinating to read the retrospective research ar-ticle in the September issue comparing 2 contrastingconventional strategies to treat growing hyperdivergentpatients (Gkantidis N, Halazonetis DJ, AlexandropoulosE, Haralabakis NB. Treatment strategies for patientswith hyperdivergent Class II Division 1 malocclusion:is vertical dimension affected? Am J Orthod Dentofa-cial Orthop 2011;140:346-55). One method wasa nonextraction approach with extrusive mechanics,and the other was an extraction approach with intru-sive mechanics. One aim was to study the wedge-effect phenomenon, which has implications in thecontrol of vertical dimensions. Although clinically im-portant conclusions were made from the study, someadditional points could have been described or con-sidered that might have led to additional importantconclusions.

First, which type of intrusive mechanics was used forthe extraction patients? As stated in the methods sec-tion, Goshgarian arches were used. But it has beenshown that these are effective for holding molars verti-cally and not for intruding them. Second, the inclusionof the second molars should have been avoided, sinceit can lead to opening the bite.

How was 5 mm of mesialization of the mandibularmolars achieved in the extraction patients, since noadditional mechanics were used, such as Class IIelastics?

The wedge-effect concept can also be applied whendistalization of molars is attempted; this should havebeen considered for the nonextraction patients. Insuch patients, the use of low-pull headgear for distaliza-tion can increase the vertical dimension.

One important variable in hyperdivergent patientsis vertical movement of the molars. This is a majorproblem; in this study, this factor needed more dis-cussion.

April 2012 � Vol 141 � Issue 4 American

I do agree with the conclusions drawn from the study,but indirectly it also highlights the importance of newervertical holding mechanics such as temporary anchoragedevices as well as functional treatments. It would be fas-cinating to view the comparison between conventionalmechanics with additional vertical holding mechanicsand modified functional strategies.

This is one of the few articles on vertical dimensionsthat highlights the role of skeletal as well as neuromus-cular functions in hyperdivergent patients by usingcontrasting treatment strategies. I commend the au-thors for their interesting and thought-provokingarticle.

Umal H. DoshiAurangabad, Maharashtra, India

Am J Orthod Dentofacial Orthop 2012;141:3960889-5406/$36.00Copyright � 2012 by the American Association of Orthodontists.doi:10.1016/j.ajodo.2012.02.016

Author’s response

We would like to thank Dr Doshi for his useful com-ments and the opportunity to discuss our article.

We contrasted 2 treatment strategies and named them“intrusive” and “extrusive” based on their intent andhow they are customarily perceived by clinicians. Theaims were to test the combined effect of all appliancesand interventions of each strategy and to evaluate theireffectiveness on vertical control. Thus, we did not askwhether intrusion is, in principle, feasible, but, rather,whether vertical control is different between these spe-cific, commonly applied treatments.

Concerning molar position, the origin of our refer-ence system was sella, so part of the molar displacementwas attributed to facial growth. In the mandibular arch,both groups showed anterior molar displacement,which was larger in the extraction group by 3 mm,due to anchorage loss during retraction. Almost 1 mmof distalization of the maxillary molars was achievedin the nonextraction group through regular use oflow-pull headgear and Class II elastics, but this didnot affect the vertical dimension differently from theother group, where mesial molar movement was evi-dent. In the extraction group, spaces were closedthrough intra-arch mechanics (power chains). The influ-ence of low-pull headgear on the vertical dimension hasbeen examined in previous studies, and similar resultswere obtained (see the “Discussion” section in ourarticle).

Journal of Orthodontics and Dentofacial Orthopedics