What does headgear add to Herbst treatment and to retention?
Department of Orthodontics, University of Hong Kong, Hong Kong, China Seminars in Orthodontics
03/2003; 9(1):57-66. DOI: 10.1053/sodo.2003.34025
This study was designed to investigate the effect of adding headgear to the Herbst appliance and the retainer, respectively. The material comprised 2 samples of consecutively treated patients with skeletal Class II malocclusions. The first sample of 22 patients (mean age, 13.2 years) was treated with high-pull headgear Herbst appliance followed by a headgear activator as a retainer, and the second sample of 14 patients (mean age, 12.9 years) was treated with Herbst appliance and an Andresen activator for retention. In both groups, the Herbst appliance was a cast silver splint type with step-by-step advancement of the mandible. Before treatment, there were no significant differences in dentofacial morphology between the groups. Changes during treatment and retention were assessed from lateral cephalograms obtained at start of treatment, after 6 months of treatment, end of treatment (12 months of treatment), and after 6 months of retention. The results showed that the maxillary forward growth was more restrained after 6 months and increasingly more during the 12 months of treatment in the headgear Herbst group, resulting in greater improvement of the jaw-base relationship in that group. The maxilla tilted in the Herbst group but not in the headgear Herbst group. During retention, the positive skeletal changes achieved during active treatment were maintained with the headgear activator, whereas with the Andresen activator there was partial relapse. The overjet correction was similar in both groups, being 9.0 and 9.7 mm, respectively. With the combined headgear concept, 70% of the overjet correction was caused by skeletal changes, whereas in the other group the skeletal contribution was less than 30%. In conclusion, adding headgear to the Herbst resulted in increased orthopedic effect on the maxilla and larger improvement of the jaw-base relationship. The choice of the retention device was critical; the headgear activator maintained the treatment results, whereas the Andresen activator had a negative effect and should not be used as a retainer after Herbst treatment.
Available from: Urban Hägg
- "A previous study of Herbst treatment showed that acceleration of mandibular growth only occurred during the initial 6-month phase of treatment, and after 6 more months by guest on May 14, 2011 ejo.oxfordjournals.org Downloaded from of extended treatment mandibular growth did not differ from normal growth, a level which was maintained during 6 months of retention with a HGA ( Hägg et al. , 2003 ). A recent experimental study demonstrated that suffi cient time after forward positioning with a fi xed jumping device was necessary to allow the newly formed condylar bone to mature and become stable, and hence enable normal growth to be maintained post-treatment ( Chayanupatkul et al. , 2003 ). "
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ABSTRACT: The aim of this study was to evaluate the effects of the headgear activator (HGA) and Herbst appliance during active treatment and retention and at follow-up in children with a skeletal Class II malocclusion. The two groups comprised 16 consecutive male patients (mean age 11.6 +/- 1.42 years) treated with a HGA and 16 male patients (mean age 12.6 +/- 1.13 years) treated with a Herbst appliance and Andresen activator (HAA) sampled from a larger pool using similar selection criteria. Growth data were obtained for the two groups. Lateral cephalograms taken at the start, after 6 months of treatment, after 12 months of active treatment or 6 months of retention, and at the 24-month follow-up were analysed. The total changes over the whole observation period (T0-T3) did not differ significantly between the groups; there was, however, a statistically significant increase in jaw prognathism (P < 0.05) and improvement of the molar relationship (P < 0.05) in the HAA group as compared with the HGA group. During the initial treatment phase (T0-T1), the overall treatment effects were statistically more pronounced in the HAA group than in the HGA group. Despite significant differences in treatment effects and changes between the two devices, there were no significant overall changes at follow-up except for the prognathism, i.e. maxillary prognathism decreased with treatment with the HGA while mandibulars prognathism continued to increase with HAA treatment.
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ABSTRACT: Muscular activity of the superficial masseter muscle and anterior portion of the temporal muscle before, during, and after treatment, with gradual advancement of the mandible, was evaluated by assessing the average integrated electromyogram (EMG) with the mandible in retruded position (RP) and incisal edge-to-edge (EE) position on 23 consecutive subjects with skeletal Class II malocclusion. Toward the end of active treatment and follow-up, the RP position and EE position coincided. At any given registration, the EMG activity of the masseter muscle was at least twice (P < .001) that of the anterior portion of the temporal muscle. The EMG activity in RP for the anterior portion of the temporal muscle was not affected significantly, whereas the EMG activity at EE position decreased significantly (P < .05) during the initial treatment, but, thereafter, it increased continuously. The difference in EMG activity between six months of follow-up and pretreatment level reached statistical significance (P < .05). For the masseter muscle, the EMG activity at both RP and EE position was reduced about 20% during the initial treatment but returned to the pretreatment level during active treatment and exceeded pretreatment level by approximately 30% to 50% at two and six months of follow-up, respectively. In conclusion, it seemed that gradual advancement affected the anterior portion of the temporal muscle to a minor extent, whereas the effect on the masseter muscle was significant.
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ABSTRACT: Growth modification has been used in orthodontics for many years, however, there has been recent increased debate about the appropriate timing and value of early phase orthopedic treatment in patients with Class II skeletal patterns. While orthopedic appliances have proven their effectiveness in correcting Class II malocclusions, the value of such treatment has recently been challenged by randomized clinical trials (RCTs) that suggest relapse of gains made in the early phase of treatment, minimizing long-term benefits. Although RCTs are a powerful tool for clinicians and researchers, they are not without their limitations and the design of such studies should be carefully considered. Relapse of orthopedic improvement may involve skeletal components, but has been found to be largely dentoalveolar in nature. Despite recent questions of the effectiveness of early treatment, it is generally recognized that the use of growth modification still has a place in modern orthodontic practices. Thus, if early phase treatment is warranted in a growing patient, greater consideration must be given to retention of not only the skeletal change, but maintenance of the dental relationship as well.
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