Date of Award

5-2009

Document Type

Thesis

Degree Name

Master of Dental Science (MDS)

Program

Orthodontics

Research Advisor

Edward F. Harris, Ph.D.

Committee

Frank Marlin Grimes, D.D.S., M.S. Joseph L. Wasson, D.D.S., M.S.

Keywords

Orthodontics, Craniofacial growth, Class II malocclusion, Functional appliance, Stages of cervical vertebral maturation

Abstract

Harnessing a patient’s growth to correct parasagittal discrepancies is an important part of Class II correction in orthodontic treatment; however, orthodontists rarely have the opportunity to choose when a patient is referred to them. Diagnostic records can assist the orthodontist in determining how much growth a patient has remaining. The purpose of this retrospective cephalometric study was to determine whether the amounts of in-treatment facial growth differ significantly by sex and by cervical vertebral maturation (CVM) stage. The sample consisted of 133 Class II division 1 patients from a single private practice office treated with a combination of a functional appliance (Bionator, Frankel or MARA) and full Edgewise appliances. This sample was compared to a conventionally treated edgewise sample of 183 Class II division 1 patients from the University of Tennessee Department of Orthodontics. The cervical vertebral maturation (CVM) stage was determined for the lateral cephalometric radiographs available for each patient using Lamparski’s original 6 stages. Amounts of facial bony growth were evaluated for 5 linear dimensions (Se-Na, Se-A, Se-B, Se-Gn, Se-Go) that occurred over the course of treatment (i.e., pre- to posttreatment changes). There was no association between CVM stage and duration of treatment. CVM stages were analyzed statistically to determine if craniofacial growth was linked to CVM grade assessed. The results showed that as individuals develop, less growth occurs with treatment. Maximum growth occurred for cases starting at CVM 1, and the average amounts of growth diminish monotonically across the 6 stages. Using a two-way ANOVA, growth for CVM stages 1-4 was highly significant for each stage as well as between sexes (P < 0.0001). Girls achieved CVM stages more than one year ahead of boys on the average, while boys have larger amounts of growth than girls at each CVM grade. Interestingly, little facial growth occurred after the age of 15 in either sex in the sample, and orthodontists need to keep this in mind if their goals are to modulate jaw growth and not rely solely on orthodontic tooth movement for correcting skeletal discrepancies.

DOI

10.21007/etd.cghs.2009.0273

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