3. Lauderdale DS, Rathouse PJ. Does bone mineralization reflecteconomic conditions? Econ Human Bio 2003;1:91-104.

JAW TRABECULAR PATTERN VARIES WITH LOCA-TION, GENDER, AGE, AND WEIGHT. Stuart C. Whiteand Kathryn A. Atchison, UCLA School of Dentistry andUCLA School of Medicine, Los Angeles, Calif

Background. Osteoporosis, one of the most common disordersin the elderly, results in over 1.5 million fractures of the hip, spine,and other sites each year in the US. Osteoporosis results in systemicloss of bone mass and microarchitectural deterioration. Dental radio-graphs potentially offer a means of screening for osteoporosis as theyare commonly made on adults and reveal bone structure. Knowledgeof anatomic variations in trabecular structure will allow optimalselection of regions to measure for risk analysis.

Objective. The objective of this project were to determinewhether the structure of trabecular pattern of the jaws of the elderlyvaries by anatomic region and by predictors of osteoporosis, includ-ing gender, age, and weight.

Methods and materials. Dental radiographs of 598 elderlywomen and 224 elderly men recruited from a long-standing epide-miologic cohort study were digitized and coded by jaw anatomicregion and gender. Areas of extraradicular bone were identified on allradiographs. The trabecular pattern was characterized using 8 strut, 2Fourier transform, 2 run length, and 1 tree analyses. Repeated mea-sures and ANOVA methods were used to examine whether trabecularstructure varied with anatomic region or gender and their interactions.Institutional Review Board approval was obtained.

Results. Each of the strut, Fourier, run length and tree analysesrevealed significant differences (P � .0001) in mean levels amonganatomic regions. For instance, the run length–4 measure of theindividual trabeculae was longest in the posterior mandible andanterior maxilla (P � .0001). The run length–4 values for men weresignificantly greater for women than for men (P � .0024). Thenumber of nodes per unit area was greater in men then in women inthe anterior and posterior mandible and the anterior maxilla. How-ever, in the posterior maxilla the number of nodes per unit was notdifferent between men and women. Further, 9 of the 13 featuresvaried with subject weight and 6 of 13 with subject age.

Conclusions. The structure of the trabecular pattern in the jawsvaries by anatomic region, age, weight, and gender. With somevariables there are significant interactions. This implies that a riskmodel for osteoporosis that includes radiographic structural featuresof the jaws will have to consider both the anatomic sites beingmeasured as well as gender, weight, and age.

NEW DEVELOPMENTS ON THIRD MOLAR IMPAC-TION DIAGNOSTICS USING 3D VOLUME RENDERINGAND 3D MODELLING TECHNIQUES. Reyes Enciso,Robert A. Danforth, Emanuel S. Alexandroni, Ahmed Memon,and James Mah, University of Southern California School ofDentistry, Los Angeles, Calif

Background. The risks from potential treatment complicationsand resultant patient morbidity associated with complex impacted“wisdom teeth” are well known.1 Further contributing to this problemare the limitations of traditional 2D radiographs. To improve riskassessment evaluation, there has been an increasing use of 3D imag-ing. Despite 3D images produced in multiple planes, the viewer isstill required to organize numerous flat images into a “mental model”

of the proposed surgical site. Development of an accurate virtualmodel would seem a valuable asset for improving risk assessmentevaluation.

Objective. The objective of this study was to create a virtualimage model of a proposed surgical site for a mandibular third molarusing data from a 3D imaging device.

Methods and materials. The patient is an adult Caucasianfemale with third molar impactions. The patient was imaged with theNewTom 9000 (QR srl, Verona, Italy), a cone-beam dental volumet-ric tomograph. The stack of axial images (8-bit 512�512 pixels)were exported to grayscale bitmap images and then imported inAmira software (TGS Inc, San Diego, Calif).

The mandibular canal and the third molar were manually seg-mented using a threshold of 120 for the third molar and 40-60 for thecanal. Once these are segmented, the software allows for creation ofa mesh or 3D model of each object, which can then be rendered fromany point of view and with any color of choice.

Results. See Fig 1.Conclusions. An interactive virtual model of a proposed surgical

site was developed. Anatomical accuracy, benefit for risk assessment,and cost effectiveness of developing the model require further inves-tigation.

REFERENCES1. Valmaseda-Castellon E, Berini-Aytes L, et al. Inferior alveolar

nerve damage after lower third molar surgical extraction: a pro-spective study of 1117 surgical extractions. Oral Surg Oral MedOral Pathol Oral Radiol Endod 2001;92:377-83.

MRI FINDINGS OF THE ARTICULAR DISK IN PATIENTSWITH TMJ LUXATION. Kiyoshi Okochi, Mizue Ida, EiichiHonda, and Tohru Kurabayashi, Tokyo Medical and DentalUniversity, Tokyo, Japan, and University of Tokushima, To-kushima, Japan

Support was received from R01 AR 47529 from the NIAMS, NIH,Bethesda, Md.

Fig 1. Simultaneous rendering of the canal, third molar mod-els, and the mandible.

Abstracts 267ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGYVolume 97, Number 2