Effects of Cervical Headgear on Overbite against the Background of Existing Growth Patterns

Abstract

Objective: To test the questions ''Does cervical headgear treatment necessarily lead to a reduction of overbite?'' and ''Are there differences in treatment results due to different growth patterns or the initial overbite?'' Materials and Methods: Initial and intermediary casts of 247 patients who had been treated exclusively with headgear were analyzed for changes in the occlusal relationship of the first molars and overbite. Orthodontic treatment consisted of the application of cervical headgear with nonangulated external arms applied at a force of 3.5-4.0 N. Only patients showing dental changes of occlusal relationship Ն4 mm during at least a 6-month treatment duration were selected. Growth patterns were identified by the y-axis values measured on lateral cephalograms obtained at study entry. Six groups were formed on the basis of these growth patterns. Results: Headgear treatment induced bite deepening in patients with vertical growth patterns and bite opening in patients with horizontal growth patterns. Further subdivision based on initial overbite revealed bite deepening in patients with small initial overbite and bite opening in patients with large initial overbite. These differences were statistically significant (P Ͻ .05). Only minor changes were observed in patients with an initial overbite of 3-4 mm. Conclusions: Overbite reductions were not dependent on the growth pattern. Orthodontists should expect bite opening in deep-bite situations and bite deepening in open-bite situations. However, initial overbite situations of 3-4 mm should not be expected to change in a significant way.

Cephalometric Analysis of Molar and Anterior Tooth Movement during Cervical Headgear Treatment in Relation to Growth Patterns

“…We did not observe this reaction consistently in our previous studies [15,16] but we did find that the headgear treatment effect varied with the types of initial growth pattern. For example, the previously described effect of clockwise rotation or bite opening was only seen in patients initially characterized by deep bite situations or a horizontal growth pattern.…”

“…Since these conclusions contradict our own observations [15,16], we decided to conduct a more detailed analysis focusing on dental changes.…”

“…Armstrong [2] stated that this molar's extrusion is the easiest to achieve but least desirable movement. Others [3,4,17,37,40,43,55] have maintained that extrusion results in clockwise rotation with corresponding bite opening.We did not observe this reaction consistently in our previous studies [15,16] but we did find that the headgear treatment effect varied with the types of initial growth pattern. For example, the previously described effect of clockwise rotation or bite opening was only seen in patients initially characterized by deep bite situations or a horizontal growth pattern.…”

“…In unseren vorigen Studien [15,16] jedoch konnten wir diese Reaktion nicht in jedem Fall sehen, sondern fanden eine Abhängigkeit der Wirkung des Headgears vom initialen Wachstumsmuster. So zeigte sich nur bei primär tiefem Biss bzw.…”

“…Angesichts der Unterschiede zwischen dieser Schlussfolgerung und den gegenteiligen Ergebnissen vorheriger Studien [15,16] erscheint eine genauere Analyse insbesondere der dentalen Veränderungen nötig. dass zwar die oberen Molaren extrudieren, der Unterkiefer jedoch in den Gruppen mit vertikalem Wachstumsmuster um die Molaren im Sinne eines Hypomochlions rotiert, was in der Folge zu einer Vertiefung des Bisses führt.…”