This study was conducted to examine the effects of maxillary quad-helix expansion on frontal and lateral cephalometric measurements in growing orthodontic patients. Twenty subjects, nine girls and eleven boys (x age = 10 years, 3 months), each exhibiting at least a unilateral posterior lingual cross-bite that had been treated with a maxillary quad-helix appliance, were selected for this study. Posterior-anterior and lateral cephalometric radio graphs were taken at the beginning of treatment (T1), when the appliance was removed (Tprog' x time = nine months) and at retention (T2) and subsequently traced. The T1 and T2 dental casts were also measured as supplement to the cephalometric measurements. Significant orthodontic changes, as seen on the frontal radiographs from T1 to Tprog' included a mean increase in maxillary intermolar width of 5.88 mm, a mean increase in average frontal molar relation of 2.95 mm and a mean increase in maxillary intercanine width of 2.74 mm. The orthopedic changes, as evidenced radiographically, included a mean increase in maxillary width of .92 mm and an increase in average maxillomandihular width of .89 mm. From the above data a 6;1 ratio of orthodontic movement to orthopedic movement was deter mined. No significant change in mandibular intermolar width was observed from the cephalometric data or the cast measurements. The most stable cases after expansion presented with normal nasal widths and narrow maxillary widths. No correlation was shown between the age of the patients and the orthopedic expansion recorded, or the amount of orthodontic/orthopedic expansion and facial type. It was concluded that all expansion changes showed little relapse from Tprog to T2, and that moderate orthopedic expansion is possible with the quad-helix, but only slight orthopedic expansion was consistently demonstrated.

LLU Discipline





Graduate School

First Advisor

J. Milford Anholm

Second Advisor

Roland D. Walters

Third Advisor

Lawrence W. Will

Fourth Advisor

Willis L. Schlenker

Fifth Advisor

Robert M. Ricketts

Sixth Advisor

Lee E. Olsen

Seventh Advisor

Gary G. Morikone

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Orthodontic Appliances



Page Count

iv; 48

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives