Long-term follow-up of patients treated with the edgewise crowned Herbst appliance in the mixed dentition

Abstract

Research has indicated that the bite jumping technique employed by the crowned Herbst appliance can be effective in correcting Class II skeletal abnormalities by promoting growth of the mandible and remodeling of the glenoid fossa. This research investigated the skeletal and dental alterations of Class II patients treated at an early age with the edgewise crowned Herbst appliance and evaluated the long term stability of those effects. Methods: Cephalometric analysis was performed for a treatment group consisting of 22 radiographs taken before phase I treatment (T1), immediately after Herbst removal during phase I treatment (T2), at the completion of phase I treatment (T3), prior to beginning of phase II orthodontic treatment (T4), and immediately following phase II orthodontic treatment (T5). Measurements were compared to a matched control sample of untreated Class II patients from the Bolton-Brush study. The difference in each variable between the treatment and control groups across the five time periods was analyzed for pooled subjects, and separately for male and female subjects. The differences between certain time points were analyzed to investigate treatment changes and their stability over time. For all time periods, the change in the values of the variables for pooled subjects, male subjects, and female subjects in the treatment group were compared to the change in the values of the variables for pooled subjects, male subjects, and female subjects in the control group, respectively. In total, 37 variables were evaluated for each group including sagittal variables, vertical variables, angular variables, and condyle/glenoid fossa variables. In addition, an evaluation of the overjet correction and molar relationship correction for the treatment groups and an evaluation of the net overjet correction and net molar relationship correction for the treatment vs. control groups at each time period for pooled subjects were performed. Results: Treatment of Class II patients treated with the crowned Herbst appliance in the early mixed dentition resulted in the following changes relative to normal growth: The forward movement of the maxillary base (OLp-A pt) was initially restrained after treatment (T2-T1) and gradually became more restrained in the short-term (T3-T1) and long-term (T4-T1) post-treatment periods. An even greater restraint was seen after phase II orthodontics (T5-T1). The mandibular base (OLp-Pg) was initially moved forward after treatment (T2-T1), however, a gradual relapse was seen in the short-term (T3-T1) and long-term (T4-T1) post-treatment periods. Additional Dr. Peter Ngan, for his lifelong commitment to education, encouragement, expertise in the clinic, and general wisdom offered on a daily basis. I consider you not only a mentor, but a true friend. Dr. Chris Martin, for his everyday advice in the clinic, friendship, assistance with practice issues, support provided on the thesis, and full-time commitment to education.

Evaluation of mandibular condylar position in different malocclusion with Gelb’s grid

“…8 Wigal et al did his study on subjects with Class II malocclusion treated with herbst appliance found significant positioning of condyle and glenoid fossa in compare to control group. 9 Vankadara et al did his study on CBCT and states that centric position is most common position of condyle and 4,7 position is the most common according to Gelb's 4,7 grid. 4,7 position is found only 11.45% in angle's Class I cases.…”

Does Appliance Design Affect Treatment Outcomes of Class II Division 1 Malocclusion? A Two-Center Retrospective Study

“…Mandibular growth is an especially important factor in the development of Class II malocclusion. Although this might stem from the maxillary prognathism, this is the less common one [ 21 ]. Skeletal Class II malocclusions usually occur as a result of downward rotation of the mandible due to mandibular deficiency or vertical growth of the maxilla [ 26 ].…”

“…TB appliance is a functional appliance consisting of two separate parts: upper and lower. During mandibular closing, opposing surfaces guide each other to close the lower jaw to the front [21]. In studies of this subject, TB appliance was found to displace the mandible forward with respect to the skull base, increase the mandibular sagittal development, inhibit the maxillary sagittal development, increase mandibular length, cause lower incisor protrusion, upper incisor retrusion, upper molar distalization and lower molar mesialization [17,[22][23][24][25].…”

Treatment effects of the Forsus Fatigue Resistant Device: A cephalometric investigation

“…Karacay 122 found a net decrease in ANB of 3.13° which was significantly more than reported in this study. The Herbst appliance has reported a 1.2° -2.6° decrease in ANB 79,89,125,128 .…”

“…Our study's findings are also very similar to findings on the Herbst appliance which show a decrease in SNA ranging from 0.5° -2.6°. 79,89,125,128 This would seem to indicate that the Forsus FRD does have a significant headgear effect and limits the forward growth of the maxilla.…”