Dental arch effects after early and later timed cervical headgear treatment—a randomized controlled trial

Abstract

<div lang="en" class="abs"><p class="abs_header">Summary</p><p><em>Background:</em>Cervical headgear (CH) is a commonly used orthodontic appliance and its dentoalveolar changes are known. However, the effects related to gender and timing have gained less attention.</p><p><em>Objectives:</em>To examine dimensions of dental arches among children with Class II occlusion without posterior mandibular rotation according to timing of Kloehn-type CH treatment.</p><p><em>Trial design:</em>Prospective, randomized, parallel-group controlled trial.</p><p><em>Methods:</em>Sixty-seven seven-year-old children with a Class II occlusion were included in the study. The children were randomized into two equal-size groups in 1:1 ratio by sealed-envelope randomization. The early group (EG, <em>n</em> = 33) was treated between T₀ and T₁ (26 months), right after eruption of the first maxillary molars. The late group (LG, <em>n</em> = 34) was treated between T₁ and T₂ (24 months). The children were treated with CH until normal Class I occlusion on first molars was achieved. Impressions for dental casts were taken from all participants at T₀, T₁, and T₂. Blinding was applicable for outcome assessors. Changes in dental cast measurements were compared between the groups and genders using t-test, Mann-Whitney U-test, and repeated measures analysis of variance.</p><p><em>Results:</em>Of the children, 56 completed the study. The maxillary arch length and the transversal changes between the upper canines and upper first molars were significantly increased in EG at T₀−T₁ (<em>P</em> < 0.001). At T₂, the transversal dimension between the upper first molars was larger (<em>P</em> < 0.05), and in the lower arch the mandibular arch length (<em>P</em> < 0.05) and the transversal dimension between the lower first molars (<em>P</em> < 0.01) were increased in EG males compared to LG males. No harms were encountered.</p><p><em>Conclusions:</em>The male gender benefits most from early timing of the CH treatment, showing larger dimensions at the end of the follow-up. The results clearly indicated a wider and longer upper dental arch and spontaneous expansion of the lower dental arch after treatment.</p><p><em>Clinical registration:</em>NCT02010346.</p></div>