Incremental versus maximum bite advancement during Herbst therapy.

Abstract

We read “Effectiveness of incremental versus maximum bite advancement during Herbst appliance therapy in late adolescent and young adult patients” in the January 2019 issue (Amuk NG, Baysal A, Coskun R, Kurt G. Am J Orthod Dentofacial Orthop 2019;155:48-56) and consider it to be an appropriate clinical study comparing treatment effects of maximum versus incremental advancement during Herbst appliance therapy in young adults. The study sample included homogeneous groups having almost the same treatment duration, which was not so in an earlier study. However, we wish to express some concerns pertaining to the results observed. Earlier studies have shown that the greater the bite jumping, the greater the intrusion, protrusion, and proclination of teeth.1Martin J. Pancherz H. Mandibular incisor position changes in relation to amount of bite jumping during Herbst/multibracket appliance treatment: a radiographic-cephalometric study.Am J Orthod Dentofacial Orthop. 2009; 136: 44-51Google Scholar The telescopic mechanism of the Herbst appliance exerts mesially and caudally directed force on mandibular anterior teeth, resulting in proclination. In this study, less protrusion and proclination of the mandibular incisors was observed in the maximum activation group. What was the maximum overjet in the sample? Were the results observed in that maximum overjet case, with maximum activation, the same in terms of lower protrusion and proclination? The basis on which the authors concluded that less protrusion and proclination of mandibular incisors occurred in the maximum activation group is unclear. In addition, the authors mentioned decreased nasolabial angle in the incremental activation group, despite backward movement of the upper lip. How this change was observed is unclear. We welcome the authors' reply. Authors' responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 155Issue 6PreviewThank you very much for your interest in our article, “Effectiveness of incremental versus maximum bite advancement during Herbst appliance therapy in late adolescent and young adult patients” (Am J Orthod Dentofacial Orthop 2019;155:48-56). Full-Text PDF