Sex dependent mechanical properties of the human mandibular condyle.
The mandibular condyle consists of articular cartilage and subchondral bone that play an important role in bearing loads at the temporomandibular joint (TMJ) during static occlusion and dynamic mastication. The objective of the current study was to examine effects of sex and cartilage on 1) static and dynamic mechanical analysis (DMA) based dynamic energy storage and dissipation for the cartilage-subchondral bone construct of the human mandibular condyle, and 2) their correlations with the tissue mineral density and trabecular morphological parameters of subchondral bone. Cartilage-subchondral bone constructs were obtained from 16 individual human cadavers (9 males, 7 females, 79.00±13.10 years). After scanning with micro-computed tomography, the specimens were subjected to a non-destructive compressive static loading up to 7N and DMA using a cyclic loading profile (-5±2N at 2Hz). After removing the cartilage from the same specimen, the series of loading experiments were repeated. Static stiffness (K) and energy dissipation (W), and dynamic storage (K'), loss (K'') stiffness, and energy dissipation (tan δ) were assessed. Gray values, which are proportional to degree of bone mineralization, and trabecular morphological parameters of the subchondral bone were also measured. After removal of the cartilage, static energy dissipation significantly decreased (p<0.009) but dynamic energy dissipation was not influenced (p>0.064). Many subchondral bone properties were significantly correlated with the overall mechanical behavior of the cartilage-subchondral bone constructs for males (p<0.047) but not females (p>0.054). However, after removal of cartilage from the constructs, all of the significant correlations were no longer found (p>0.057). The current findings indicate that the subchondral bone is responsible for bearing static and dynamic loading in males but not in females. This result indicates that the female condyle may have a mechanically disadvantageous TMJ loading environment.
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA. Electronic address: kim.2508@osu.edu.
Do-Gyoon
DG
Kim
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA.
Arman
A
Haghighi
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA.
Hyun-Jung
HJ
Kwon
Musculoskeletal Biomechanics, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA.
Jessica S
JS
Coogan
Musculoskeletal Biomechanics, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA.
Daniel P
DP
Nicolella
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA.
Trenton B
TB
Johnson
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA.
Hwan D
HD
Kim
Division of Orthodontics, College of Dentistry, The Ohio State University, 4088 Postle Hall 305 W. 12th Ave, Columbus, OH 43210, USA.
Nari
N
Kim
Injury Biomechanics Research Center, College of Medicine, The Ohio State University, Columbus, OH 43210, USA.
Amanda M
AM
Agnew
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008335:Mandibular Condyle / Q000502:physiology*; D008409:Mastication; D012727:Sex Characteristics; D013704:Temporomandibular Joint / Q000502:physiology; D055114:X-Ray Microtomography
Biomechanics; Cartilage; Dynamic mechanical analysis; Sex differences; Subchondral bone; Temporomandibular disorders