Micromechanics/structure relationships in the human mandible.
OBJECTIVE
A clear understanding of the relationship between the micromechanical properties and orientation of the osteons within the mandible is important to understand mandibular function, fracture repair, treatment of temporo-mandibular joint disorders, the materials and organization of dental implants. The objective of this research was to obtain the micromechanical properties of human mandibular cortical bone as a function of orientation from TMJ to TMJ.


METHODS
A mandible obtained from a deceased 66 year-old female free of bone disease was used. The mandible was embedded in polymethylmethacrylate. The micromechanical properties analysis was obtained using the UH3 scanning acoustic microscope (SAM; Olympus Co., Tokyo, Japan). The coordinates system is defined such that the inferior border of mandibular is positioned on the x-y plane. x is along the anterior-posterior direction, y is in the horizontal direction and z is in superior-inferior direction.


RESULTS
The osteonal orientations were almost parallel to the x axis and eventually branched into two directions towards the coronoid process and condylar head. The SAM revealed that almost the whole area of the mandible body was found to be transversely isotropic in the plane perpendicular to the x axis. In the parallel and oblique directions, all data were transversely isotropic with respect to the x axis. Data of the perpendicular osteons were transversely isotropic with respect to the z axis.


CONCLUSIONS
Having actual micromechanical properties as a function of orientation in the mandible could provide base line data for: fracture repair; choice of bone replacement materials.
Nomura
Tsutomu
T
Department of Tissue Regeneration and Reconstruction, Reconstructive Surgery for Oral and Maxillofacial Region, Niigata University, 2-5274 Gakkocho-Dori, 951-8514, Niigata City, Japan. t-nomura@dent.niigata-u.ac.jp
Gold
Evan
E
Powers
Michael P
MP
Shingaki
Susumu
S
Katz
J Lawrence
JL
D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D004548:Elasticity; D005260:Female; D006253:Haversian System / Q000502:physiology / Q000648:ultrastructure*; D006801:Humans; D007575:Jaw, Edentulous / Q000473:pathology / Q000503:physiopathology; D008334:Mandible / Q000033:anatomy & histology* / Q000502:physiology; D008335:Mandibular Condyle / Q000033:anatomy & histology / Q000502:physiology; D033401:Microscopy, Acoustic; D013314:Stress, Mechanical