IADR Abstract Archives
Human Temporomandibular Capsule-Ligament Complex Structure-Function: Tensile Viscoelasticity and Collagen Ultrastructure
Objectives: Temporomandibular joint disorders (TMJDs) are of unknown etiology, with women 3-8 times more likely to be treated than men. The temporomandibular lateral capsule-ligament (LCL) complex spans the temporal bone and mandibular condyle, and through a pathologic ‘loose ligament’ phenomena could lead to TMJD development. The objective of this study was to determine baseline, sex-specific differences in region-dependent LCL complex tensile properties and collagen ultrastructure, to evaluate human LCL complex structure-function relationships.
Methods: Intact human temporomandibular joints (TMJs) were excised, and the superficial surface of the fresh, intact, unstained LCL surface was imaged using second-harmonic generation (SHG) microscopy. SHG images were quantified, determining LCL complex collagen fiber alignment and bundle diameter. LCL complexes were then dissected into anterior and posterior segments, and bone-LCL-bone specimens underwent a stress-relaxation protocol, determining LCL complex tensile modulus and quasi-linear viscoelastic (QLV) parameters.
Results: Intact LCL complexes successfully underwent SHG microscopy and tensile stress-relaxation testing, and collagen fiber alignment, bundle diameter, Young’s Modulus and QLV parameters were quantified. Descriptive statistics were calculated. Statistical differences between males and females in SHG parameters were determined using a repeated measures one-way ANOVA. Statistical differences in tensile material properties between males and females and anterior and posterior segments were determined using a two-way ANOVA.
Conclusions: These findings establish important sex-specific and region specific properties of the human LCL complex. Sex-specific differences are critical towards identifying potential etiological mechanisms behind TMJD development, while region dependent differences are critical towards evaluating the function of this poorly understood structure. Additionally, baseline tensile properties are critical for the development of temporomandibular musculoskeletal models. In conclusion, these results provide critical baseline sex-specific and region-specific properties for the LCL complex, and further our understanding of the LCL complex role in maintaining physiologic approximation between TMJ articular components.
Methods: Intact human temporomandibular joints (TMJs) were excised, and the superficial surface of the fresh, intact, unstained LCL surface was imaged using second-harmonic generation (SHG) microscopy. SHG images were quantified, determining LCL complex collagen fiber alignment and bundle diameter. LCL complexes were then dissected into anterior and posterior segments, and bone-LCL-bone specimens underwent a stress-relaxation protocol, determining LCL complex tensile modulus and quasi-linear viscoelastic (QLV) parameters.
Results: Intact LCL complexes successfully underwent SHG microscopy and tensile stress-relaxation testing, and collagen fiber alignment, bundle diameter, Young’s Modulus and QLV parameters were quantified. Descriptive statistics were calculated. Statistical differences between males and females in SHG parameters were determined using a repeated measures one-way ANOVA. Statistical differences in tensile material properties between males and females and anterior and posterior segments were determined using a two-way ANOVA.
Conclusions: These findings establish important sex-specific and region specific properties of the human LCL complex. Sex-specific differences are critical towards identifying potential etiological mechanisms behind TMJD development, while region dependent differences are critical towards evaluating the function of this poorly understood structure. Additionally, baseline tensile properties are critical for the development of temporomandibular musculoskeletal models. In conclusion, these results provide critical baseline sex-specific and region-specific properties for the LCL complex, and further our understanding of the LCL complex role in maintaining physiologic approximation between TMJ articular components.