Method: Procurement of fresh human mandibles through the National Disease Research Interchange was approved through GHSU-IRB. The specimens had no osteoporosis, cancers, or were missing molar(s) unilaterally. The bone was x-rayed and scanned using skyscan 1174 microCT. Samples of bone were removed from the dentulous and edentulous sections in both the alveolar and basal regions. RNA was extracted and integrity tested. Real time PCR was used to evaluate expression of Receptor Activator of Nuclear-factor Kappa-B Ligand (RANKL) and Osteoprotegerin (OPG).
Result: The bone mineral density of alveolar and basal bone from dentulous regions was comparable to that of the inferior border, while the BMD of edentulous bone was 15-18% lower than that of the inferior border. The BMD of alveolar-buccal bone from dentulous regions was 11% higher than that of basal-buccal bone. The remaining alveolar ridge also showed an increase in BMD over basal-cancellous bone. BMD measurements from dentulous specimens generally were greater than 10% higher than the comparable edentulous regions. Comparisons of OPG expression in alveolar vs basal bone or edentulous vs dentulous regions showed higher level expression in alveolar and edentulous samples (52-fold and 5-fold, respectively). OPG expression was 333-fold higher in alveolar-edentulous bone than in alveolar-dentulous bone. RANKL was down-regulated 269-fold in basal-edentulous as compared to alveolar-edentulous samples. No differences were measured in basal bone from edentulous and dentulous samples.
Conclusion: Evaluations of human mandibles revealed measureable differences between alveolar and basal bone as well as edentulous and dentulous bone. These studies laid the foundation for more comprehensive evaluations of these difficult to obtain tissues.