Regional variation of bone tissue properties at the human mandibular condyle

Abstract

The temporomandibular joint (TMJ) bears different types of static and dynamic loading during occlusion and mastication. As such, characteristics of mandibular condylar bone tissue play an important role in determining the mechanical stability of the TMJ under the macro-level loading. Thus, the objective of this study was to examine regional variation of the elastic, plastic, and viscoelastic mechanical properties of human mandibular condylar bone tissue using nanoindentation. Cortical and trabecular bone were dissected from mandibular condyles of human cadavers (9 males, 54 to 96 years). These specimens were scanned using microcomputed tomography to obtain bone tissue mineral distribution. Then, nanoindentation was conducted on the surface of the same specimens in hydration. Plastic hardness (H) at a peak load, viscoelastic creep (Creep/Pmax), viscosity (η), and tangent delta (tan δ) during a 30 second hold period, and elastic modulus (E) during unloading were obtained by a cycle of indentation at the same site of bone tissue. The tissue mineral and nanoindentation parameters were analyzed for the periosteal and endosteal cortex, and trabecular bone regions of the mandibular condyle. The more mineralized periosteal cortex had higher mean values of elastic modulus, plastic hardness, and viscosity but lower viscoelastic creep and tan δ than the less mineralized trabecular bone of the mandibular condyle. These characteristics of bone tissue suggest that the periosteal cortex tissue may have more effective properties to resist elastic, plastic, and viscoelastic deformation under static loading, and the trabecular bone tissue to absorb and dissipate time-dependent viscoelastic loading energy at the TMJ during static occlusion and dynamic mastication.

Salicylic acid (SA)‐eluting bone regeneration scaffolds with interconnected porosity and local and sustained SA release

“…This range is relatively wide because the bone mechanical properties and load‐bearing requirement vary widely in vivo . As the modulus of the scaffolds presented herein is on the lower end of the range of bone, they may be more suitable for mandibular or calvarial bone regeneration, which does not require high mechanical loading …”

“…As the modulus of the scaffolds presented herein is on the lower end of the range of bone, they may be more suitable for mandibular or calvarial bone regeneration, which does not require high mechanical loading. 44,45 Comparing the 1:1 and 2:1 SAA:OCOX scaffolds, the 2:1 SAA:OCOX scaffold has higher drug loading and a longer SA release window but a lower modulus compared to the 1:1 SAA:OCOX scaffold. Therefore, if the application does not require high modulus, such as calvarial bone regeneration, the 2:1 ratio scaffold is more desirable as it offers a longer therapeutic window.…”

Comparison of the Accuracy of Implant Position Using Surgical Guides Fabricated by Additive and Subtractive Techniques

“…Diagonal indentations were measured using a microscope. Vickers hardness (HV) (70,71) were calculated by the equation 1.…”

“…Where d is the average length of diagonal which can be calculated from (d1+d2) /2. (70) . From this preliminary study, the dental model resin was chosen as it has the hardness closest to the mean hardness of average mandibular bone.…”

Conditions and calibration to obtain comparable grey values between different clinical cone beam computed tomography scanners

“…Recently, more parameters (variability and 5 percentile low and high) were introduced to describe the alteration of mineral distribution resulting from bone modelling and remodelling at the tissue level. 17,18 However, it remains to be determined whether these parameters can be assessed using the CBCT-based BMD at the macro level.…”