Are Age-Associated Changes in the Facial Skeleton Attributable to Loss of Bone Mineral Density?

Goals/Purpose: Our understanding of facial aging changes has evolved greatly to encompass measured changes in both soft tissue and bony structures.  The impact of skeletal support on facial esthetics is well established, however the exact mechanism of bony facial changes over time is not fully understood.  It is unknown if skeletal processes demonstrated in facial aging are more accurately attributed to loss of bone mineral density or other local or systemic factors.  This study evaluates dual-energy X-ray absorptiometry (DEXA) as a predictor of skeletal facial changes.

Methods/Technique: In this IRB-approved retrospective study, patients were identified by querying institutional databases for patients who recently obtained both a maxillofacial CT and a DEXA scan. Maxillofacial CT scans were obtained from 32 patients with recent DEXA scans.  The study population consisted of 16 osteoporotic and normal, age-controlled, female subjects.  Each CT scan was rendered as a three-dimensional model and multiple measurements were obtained by a blinded examiner.  Linear regression analysis was also performed between each measurement and age versus bone mineral density.

Results/Complications: With age there is a statistically significant increase in condylar width and maxillary retrusion as well as a decrease in ramus height and width that is independent of bone mineral density.  There is a significant increase in orbital area and glabellar angle that nears significance, independent of bone mineral density.  Maxillary angle and maxillary height significantly decrease with age yet increases significantly in osteoporosis. 

Conclusion: This is the first study to link bone mineral density to facial skeletal changes.  Chronologic age is a better predictor of most progressive changes in the facial skeleton.  Loss of bone mineral density does not correlate with these.  Local effects of aging soft tissues may have a greater effect on bone structure than bone mineralization itself.