Date of Award

5-2006

Document Type

Thesis

Degree Name

Master of Dental Science (MDS)

Program

Orthodontics

Research Advisor

Edward Harris, Ph.D.

Committee

James L Vaden, D.D.S., M.S. Quinton C Robinson, D.D.S., M.S.

Abstract

Most studies of facial growth in adults have relied on cross-sectional data. Longitudinal studies in this area are scarce because it is difficult to collect data on adults across time and because the changes are less dramatic than during childhood or adolescence. An interesting sample exists in the Charles H. Tweed collection, where orthodontic patients were recalled 10 or more years after treatment with an average time out of treatment of about 15 years. The availability of frontal facial photographs from this collection provided us with an uncommon opportunity to longitudinally quantify the changes in facial dimensions from adolescence into early adulthood. Frontal photographs were obtained from 101 subjects (41 males and 60 females) at posttreatment ( x = 15.6 years) and long-term recall ( x = 31.2 years) examinations. 7 transverse and 9 craniocaudal distances were measured to quantify facial growth and to assess the extents of sexual dimorphism of the face across the age span. Transverse dimensions generally increased significantly in both sexes with Lower face width (GoL-GoR) increasing more than any other measurement for both men (18%) and women (7%), which apparently is due to weight gain expressed in the cheeks. There also were unanticipated reductions in facial widths, namely in Inner canthus width (EnL-EnR), Outer canthus width (ExL-ExR), and Alar width (AlL-AlR). The transverse changes were sexually dimorphic, with men experiencing larger average changes. Craniocaudal changes were smaller than the transverse changes and not generally sexually dimorphic, except for Lower face height (Sn-Me) and its most influential component, Chin height (Li-Me). There was a fundamental difference in the development of Lower face height between men and women mainly because Chin height was significantly different in men and women (8% and 2%, respectively), suggesting that men have a considerably larger soft tissue addition to bony chin than women during this age interval. As a result of transverse and craniocaudal changes, the face becomes broader mediolaterally and, to a lesser degree, longer craniocaudally. Lower face width increased more than twice the amount of any craniocaudal distance. Orthodontists should be aware that continued growth alters facial sizes and proportionality in early adulthood, and treatment planning should be complementary to the anticipated facial growth in adolescent patients.

DOI

10.21007/etd.cghs.2006.0142

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