Three-dimensional evaluation of mandibular changes associated with Herbst treatment in growing Class II patients: pilot study Public Deposited

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  • March 19, 2019
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  • Covington, Thomas
    • Affiliation: School of Dentistry, Department of Orthodontics
Abstract
  • Introduction: Herbst appliance treatment of Class II malocclusion is common in orthodontic offices. Recent advances in 3D superimpositions have allowed semi-quantitative assessment of skeletal and dental changes accompanied with Herbst treatment. The aim of this study was to evaluate 3D skeletal and dental changes following Herbst removal. Methods: 7 consecutive Herbst patients had CBCTs taken pre-treatment (T1¬), post Herbst removal (T2), and one year following Herbst treatment (T3). 3-D models were generated from CBCTs; anterior cranial base registrations were performed to evaluate morphological changes of the maxillary and mandibular skeleton. Mandibular registrations on the inner cortical symphysis were performed to evaluate mandibular growth and displacement as well as mandibular dental changes. Registered models were analyzed using color maps and vector based anatomical point-to-point measurements. Results: During initial Herbst treatment, patients demonstrated anterior translation of glenoid fossa and condyles and anterior projection of B point, however; variable skeletal changes were observed one-year post Herbst removal. 4-patients demonstrated a posterior displacement and 3-patients had continued anterior displacement of B-point (0.88mm+/-2.54mm). The later three demonstrated inferior displacement of the glenoid fossa/condyle complex leading to a counter clockwise rotation of the mandible one year post Herbst removal. All patients showed posterior displacement of the glenoid fossa and condyles one year post Herbst. While there was a significant maxillary restraining effect during Herbst application, insignificant anterior/posterior changes were seen following Herbst removal. Conclusions: Maxillary skeletal changes during Herbst treatment were maintained; however anterior/posterior changes in mandibular position one year post Herbst removal were variable. Condyle fossa complex moved anterior during Herbst treatment but was displaced posterior one year following treatment. Inferior positioning of the glenoid fossa/condyle complex may have a larger change in the AP position of the mandible.
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  • In Copyright
Advisor
  • Nguyen, Tung
  • Paniagua, Beatriz
  • Ko, Ching-Chang
Degree
  • Master of Science
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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