- Email: [email protected]
Contrast-enhanced microCT for assessment of articular cartilage and bone morphology in the jaw joint
S258
Abstracts / Bone 44 (2009) S253–S338
herein provide a robust prior-art for translating this technique to the analysis of osteointegration in human biopsies. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.439
P014 Biomechanical effect of mineral heterogeneity in human trabecular bone G.A.P. Rendersa,*, L. Mulderb, G.E.J. Langenbacha, L.J. Van Ruijvena, J.H. Koolstraa, T.M.G. Van Eijdena a Functional Anatomy, Academic Centre for Dentistry Amsterdam, Amsterdam b Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands Due to daily loading, trabecular bone is subjected to deformations (i.e., strain), which lead to stress in the bone tissue. When stress and/or strain deviates from the normal range, the bone architecture and its degree of mineralization (DMB) adapts to effectively withstand the sustained altered loading. The consequences of architecture and DMB on apparent bone stiffness have been predicted with finite element (FE) models. Recently, it has been demonstrated that in developing porcine bone the estimation of apparent mechanical behavior is considerably influenced when the effects of mineral heterogeneity are taken into account. To investigate to what extent the distribution of mineralization affects the apparent bone stiffness of the human mandibular condyle, i.e., apparent Young's and shear moduli of the trabecular structure. Nine right condyles from embalmed human dentate mandibles were scanned and evaluated with a microCT 40 system (Scanco medical AG, Switzerland, resolution: 18 μm). Cubic regional volumes of interest were selected to construct FE models. The tissue modulus of each element was scaled to the local DMB as determined using microCT. In a second model, the heterogeneity of DMB was disregarded and the tissue modulus was (artificially) set to 9.0 GPa. For each model, three compression and three shear tests were simulated. A general linear model for repeated measures was used to test for differences between both FE models of the same volume of interest. Correlations between architectural and mechanical properties were explored by taking all specimens into account. In all tests a p-value of less than 0.05 was considered statistically significant. Disregard of mineralization variation in FE models caused an increase in the apparent Young's and shear moduli up to 21%. When this property was included, the apparent moduli correlated significantly with bone volume fraction and DMB. Bone volume fraction accounted for up to 82% of the variation in apparent moduli whereas DMB accounted for up to 29% in this variation. Disregarding the mineral heterogeneity was found to lead to a considerable overestimation of apparent elastic bone moduli in FE models. Therefore, incorporation of this variable may give more realistic predictions of bone mechanical properties. This project was funded by the Netherlands Organisation for Scientific Research (NWO, 021.001.050) and sponsored by the National Computing Facilities Foundation (NCF). Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.440
P015 Contrast-enhanced microCT for assessment of articular cartilage and bone morphology in the jaw joint G.A.P. Rendersa,*, L. Mulderb, G.E.J. Langenbacha, J.H. Koolstraa a Functional Anatomy, Academic Centre for Dentistry Amsterdam, Amsterdam, Netherlands b Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands During the initiation and/or progression of osteoarthritis (OA), changes in the cartilage-bone interaction can be expected. Contrastenhanced microCT has successfully been used for cartilage assessment in rat knees. The aim of our study was to investigate whether this method can be applied for bone-cartilage interaction-research with microCT in the human temporomandibular joint (TMJ). Six embalmed human mandibular condyles were used (3 healthy, OA samples). Each sample was treated with the contrast medium Hexabrix 320 (40%) with incubation times ranging from 15–1200 min (37 °C). The samples were scanned at a resolution of 18 μm (microCT 40, Scanco medical AG, Switzerland) in air. Volumes of interest were selected containing bone, cartilage, and background. From the resulting attenuation histogram, the location of the peak corresponding to contrast-enhanced articular cartilage was analyzed to determine the minimal incubation time. A general linear model for repeated measures was used to test for differences between different incubation times, and between healthy and OA samples. A p-value of less than 0.05 was considered statistically significant. There were no significant differences between the healthy and OA group. Therefore, the data from the six samples were averaged. The cartilage attenuation increased with the Hexabrix incubation time from 15–60 min and then became stable. The increase up to 30 min was found to be statistically significant (p < 0.001). Giving this information we concluded that the minimal incubation time should be 60 min. This was applied for further research on healthy condyles. The bone or cartilage region was selected and different thresholds allowed for individual segmentation. Thus, quantitative assessment of articular cartilage (average thickness: 0.37 ± 0.16 mm) was feasible and could be combined with bone morphology and mineralization data. MicroCT quantitative measures on TMJ articular cartilage have been demonstrated to be possible after contrast enhancement with Hexabrix 320 for 60 min. The morphological information on cartilage can be combined with quantitative bone assessment allowing for research into the interaction between cartilage and bone morphology and eventually biomechanics. Ongoing work consists of interactionresearch and comparison of interactions between healthy and OA joints. This project was funded by the Dutch Organisation for Scientific Research (NWO, 021.001.050). Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.441
P016 Structure and chemical composition of apatite crystal in dermal exoskeleton and tooth of eusthenopteron from Devonian H. Mishimaa,*, M. Kakeib, Y. Miakec a Department of Medical Hygiene, Kochi Gakuen College, Kochi, Japan b Division of Oral Anatomy, School of Dentistry, Mekai University, Sakado, Japan c Department of Ultrastrucral Science, Oral Health Science Center, Tokyo Dental College, Chiba, Japan Eusthenopteron come under the rhipidistians. Little information is available regarding the ultrastructure and properties of the dermal
Abstracts / Bone 44 (2009) S253–S338
herein provide a robust prior-art for translating this technique to the analysis of osteointegration in human biopsies. Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.439
P014 Biomechanical effect of mineral heterogeneity in human trabecular bone G.A.P. Rendersa,*, L. Mulderb, G.E.J. Langenbacha, L.J. Van Ruijvena, J.H. Koolstraa, T.M.G. Van Eijdena a Functional Anatomy, Academic Centre for Dentistry Amsterdam, Amsterdam b Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands Due to daily loading, trabecular bone is subjected to deformations (i.e., strain), which lead to stress in the bone tissue. When stress and/or strain deviates from the normal range, the bone architecture and its degree of mineralization (DMB) adapts to effectively withstand the sustained altered loading. The consequences of architecture and DMB on apparent bone stiffness have been predicted with finite element (FE) models. Recently, it has been demonstrated that in developing porcine bone the estimation of apparent mechanical behavior is considerably influenced when the effects of mineral heterogeneity are taken into account. To investigate to what extent the distribution of mineralization affects the apparent bone stiffness of the human mandibular condyle, i.e., apparent Young's and shear moduli of the trabecular structure. Nine right condyles from embalmed human dentate mandibles were scanned and evaluated with a microCT 40 system (Scanco medical AG, Switzerland, resolution: 18 μm). Cubic regional volumes of interest were selected to construct FE models. The tissue modulus of each element was scaled to the local DMB as determined using microCT. In a second model, the heterogeneity of DMB was disregarded and the tissue modulus was (artificially) set to 9.0 GPa. For each model, three compression and three shear tests were simulated. A general linear model for repeated measures was used to test for differences between both FE models of the same volume of interest. Correlations between architectural and mechanical properties were explored by taking all specimens into account. In all tests a p-value of less than 0.05 was considered statistically significant. Disregard of mineralization variation in FE models caused an increase in the apparent Young's and shear moduli up to 21%. When this property was included, the apparent moduli correlated significantly with bone volume fraction and DMB. Bone volume fraction accounted for up to 82% of the variation in apparent moduli whereas DMB accounted for up to 29% in this variation. Disregarding the mineral heterogeneity was found to lead to a considerable overestimation of apparent elastic bone moduli in FE models. Therefore, incorporation of this variable may give more realistic predictions of bone mechanical properties. This project was funded by the Netherlands Organisation for Scientific Research (NWO, 021.001.050) and sponsored by the National Computing Facilities Foundation (NCF). Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.440
P015 Contrast-enhanced microCT for assessment of articular cartilage and bone morphology in the jaw joint G.A.P. Rendersa,*, L. Mulderb, G.E.J. Langenbacha, J.H. Koolstraa a Functional Anatomy, Academic Centre for Dentistry Amsterdam, Amsterdam, Netherlands b Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands During the initiation and/or progression of osteoarthritis (OA), changes in the cartilage-bone interaction can be expected. Contrastenhanced microCT has successfully been used for cartilage assessment in rat knees. The aim of our study was to investigate whether this method can be applied for bone-cartilage interaction-research with microCT in the human temporomandibular joint (TMJ). Six embalmed human mandibular condyles were used (3 healthy, OA samples). Each sample was treated with the contrast medium Hexabrix 320 (40%) with incubation times ranging from 15–1200 min (37 °C). The samples were scanned at a resolution of 18 μm (microCT 40, Scanco medical AG, Switzerland) in air. Volumes of interest were selected containing bone, cartilage, and background. From the resulting attenuation histogram, the location of the peak corresponding to contrast-enhanced articular cartilage was analyzed to determine the minimal incubation time. A general linear model for repeated measures was used to test for differences between different incubation times, and between healthy and OA samples. A p-value of less than 0.05 was considered statistically significant. There were no significant differences between the healthy and OA group. Therefore, the data from the six samples were averaged. The cartilage attenuation increased with the Hexabrix incubation time from 15–60 min and then became stable. The increase up to 30 min was found to be statistically significant (p < 0.001). Giving this information we concluded that the minimal incubation time should be 60 min. This was applied for further research on healthy condyles. The bone or cartilage region was selected and different thresholds allowed for individual segmentation. Thus, quantitative assessment of articular cartilage (average thickness: 0.37 ± 0.16 mm) was feasible and could be combined with bone morphology and mineralization data. MicroCT quantitative measures on TMJ articular cartilage have been demonstrated to be possible after contrast enhancement with Hexabrix 320 for 60 min. The morphological information on cartilage can be combined with quantitative bone assessment allowing for research into the interaction between cartilage and bone morphology and eventually biomechanics. Ongoing work consists of interactionresearch and comparison of interactions between healthy and OA joints. This project was funded by the Dutch Organisation for Scientific Research (NWO, 021.001.050). Conflict of interest: None declared. doi:10.1016/j.bone.2009.03.441
P016 Structure and chemical composition of apatite crystal in dermal exoskeleton and tooth of eusthenopteron from Devonian H. Mishimaa,*, M. Kakeib, Y. Miakec a Department of Medical Hygiene, Kochi Gakuen College, Kochi, Japan b Division of Oral Anatomy, School of Dentistry, Mekai University, Sakado, Japan c Department of Ultrastrucral Science, Oral Health Science Center, Tokyo Dental College, Chiba, Japan Eusthenopteron come under the rhipidistians. Little information is available regarding the ultrastructure and properties of the dermal