Effects of headgear timing on dental arch changes from 7 to 18 years of age: a follow-up study.

BACKGROUND: Dental arch effects after cervical headgear (CHG) treatment have been researched from several different perspectives. However, the long-term effects of CHG timing are still unknown. OBJECTIVES: To analyse the long-term effects of CHG timing on dental arches. MATERIAL AND METHODS: A total of 67 children with Angle Class II malocclusion comprised the study group in this trial. The participants were randomized into two equal-sized groups. In the early group (EG, n = 33), treatment was started after the eruption of the first upper molars. In the later-timed group (LG, n = 34), treatment was started 18 months later compared with the early group. Long-term effects were measured from dental casts taken at five time points between 7 and 18 years of age. RESULTS: The total maxillary dental arch length was achieved earlier, the gained length persisted better in the long term, and significantly more space was achieved in EG compared with LG (P = .048). The intermolar width in the maxillary dental arch was more stable and was reached earlier in EG compared with LG (P = .002). The results showed that in terms of total mandibular arch length increases, EG males benefited the most and LG females the least from CHG treatment (P = .031). CONCLUSIONS: Both genders benefited from earlier CHG treatment. The maxillary dental arches remained longer, and the final width was gained earlier in EG compared with LG.

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

BACKGROUND: 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. OBJECTIVES: To examine dimensions of dental arches among children with Class II occlusion without posterior mandibular rotation according to timing of Kloehn-type CH treatment. TRIAL DESIGN: Prospective, randomized, parallel-group controlled trial. METHODS: 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, n = 33) was treated between T0 and T1 (26 months), right after eruption of the first maxillary molars. The late group (LG, n = 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. RESULTS: 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 (P < 0.001). At T2, the transversal dimension between the upper first molars was larger (P < 0.05), and in the lower arch the mandibular arch length (P < 0.05) and the transversal dimension between the lower first molars (P < 0.01) were increased in EG males compared to LG males. No harms were encountered. CONCLUSIONS: 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. CLINICAL REGISTRATION: NCT02010346.