Shelton Hsu


Distraction osteogenesis (DO) is the gradual lengthening of a healing bone. This surgical technique can be applied to the jawbone to correct an asymmetry or deficiency of the mandible. DO has been added to the list of treatment options for patients with craniofacial anomalies or excessive dental crowding.

Although mandibular distraction osteogenesis has been successfully performed in many patients, the comprehensive effects on the TMJ are not fully understood. The purpose of this study is to compare the amount of rotational and positional change that occurs at the condyles when the rabbit mandible is widened at the midline and paramedian locations.

Rabbits have been used as an appropriate model for studying mandibular DO and TMJ disorders. The study included 16 rabbits: 9 midline DO, 6 paramedian DO, and 1 control. Corticotomies were performed at the designated sites and jackscrew expanders were fixated to the bony segments. After a brief latency, the expansion devices were activated Imm/day. Expansion continued for 10 days to a maximum of 10 mm. The rabbits had submentovertex radiographs taken at each activation interval. The films were traced, measured and compared for changes in mandibular rotation. The rabbits also underwent a NewTom CT scan that rendered 2-D and 3-D images of the rabbit skull and condyles. CT reconstructions were analyzed for changes in joint space and intercondylar distance.

Results showed that there was a predictable and consistent amount of condylar rotation associated with each millimeter of mandibular midline distraction. With paramedian distraction, the unexpanded side of the mandible also showed a regular increase in condylar rotation. However, the condyle on the expanded side of paramedian distraction underwent irregular rotations. The paramedian DO of the mandible produced unpredictable rotational change and condylar displacement on the side of distraction.

LLU Discipline

Orthodontics and Dentofacial Orthopedics


Orthodontics and Dentofacial Orthopedics


Graduate School

First Advisor

Joseph M. Caruso

Second Advisor

Alan Herford

Third Advisor

Jay Kim

Fourth Advisor

Leroy Leggitt

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Maxillofacial Abnormalities -- Surgery; Osteogenesis; Facial Bones -- Surgery; Bone lengthening -- surgery.



Page Count

xii; 53

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