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Osseointegration of ceramic dental implants
Track 8. Computer-Assisted Surgery
tissues as viscoelastic continua. The loading conditions during clenching were given by the contraction forces of the masticatory muscles exerted during clenching. In the connective tissue surrounding the disc, the high stress/strain were observed mainly in the retrodiscal region. In particular, the retrodiscal tissue strain almost tripled with time by the continuous clenching. In addition, the anterior displacement of the disc increased with time also. The disc displacement in anterior direction was larger when the disc attachment area of the superior head of lateral pterygoid muscle (SLPM) was larger. These results confirmed that the continuous clenching is associated with the anterior disc displacement (ADD), and that the excessive activity of SLPM is a risk factor for ADD. 6965 We-Th, no. 17 (P62) Osseointegration of ceramic dental implants S. KSbel, O. Bothe, W. Weber. Metexit AG, Thayngen, Switzerland This study reviews osseointegration of ceramic dental implants. Latest results of the bone response to zirconia ceramic implants are also presented. Zirconia ceramic, i.e. Y-TZP, has a favourable combination of an excellent biocompatibility and high mechanical strength. Over the past years, several studies were conducted on osseointegration of zirconia dental implants. These studies are briefly reviewed and the performance and limitations of zirconia and titanium implants are compared. Recent results are presented showing that even after 4 to 6 weeks of healing zirconia implants reach high stability in the bone as determined by the resistance to torque forces. Histological and clinical studies support these findings. Zirconia ceramic implants show excellent performance and are therefore an excellent alternative to titantium implants for many indications. 6063 We-Th, no. 18 (P62) From quantum to biomechanics: improving the host response to implantable devices P.G. Coelho 1, J.E. Lemons 2, J. Nilo Freire3, A.L. Coelho4. 1Biomaterials and
Biomimetics, New York University, New York, NY, USA, 2 prosthodontics and Biomaterials, University of Alabama at Birmingham, Birmingham, AL, USA, 3private Practice, Florianepolis, Brazil, 4UNICENP, Curitiba, Brazil Nanotechnology has strongly affected biomaterials science, since reduced matter domains (quantum confined) may deeply alter its electronic/thermodynamic properties and thus the response of living tissues. This presentation focuses on a series of in-vitro and in-vive studies concerning controlled bioceramic surface engineering processes (ion beam assisted deposition - IBAD) which yielded Ca- and P-based coatings ranging from 300 to 5000 angstroms. The in-vitro studies comprised FESEM, EDS, ionmilling + XPS for depth profiling, ToF-SIMS, and thin-film XRD. Two animal studies comprised the in-vivo part of the series. The first in-vivo protocol was utilized for osseoactivity, osseointegration (bone to implant contact - BIC), and biomechanical fixation assessment of 300-500A bioceramic coatings versus a noncoated implant (control). The second animal model analyzed mineral apposition rates (MAR), osseointegration, and biomechanical fixation of 200500A bioceramic coated implants, 2000-5000A bioceramic coated implants, noncoated implants (control), and plasma sprayed HA (PSHA) coated implants. The in-vitro results showed that the nanothick coatings were of Ca- and P-basic composition and presented amorphous microstructures. In addition, coating stoichiometry varied as a function of coating depth. The first animal model showed that significantly higher osseoactivity levels were found for 200-500A bioceramic coated implants. The second animal investigation showed that 2000-5000A bioceramic coated implants and PSHA presented higher degrees of BIC and biomechanical fixation at 3 and 5 weeks in-vivo compared to other groups. MAR values presented complex patterns as time elapsed in-vivo, with 2000-5000A bioceramic coated implants and noncoated implants presenting higher values at 3 and 5 weeks in-vivo. According to this series of studies, it can be concluded that nanothick bioceramic coatings, if processed to a thickness of 2000-5000A, enhance the biological response of bone to implant to levels comparable to PSHA. 4409 We-Th, no. 19 (P62) Pressure simulation of orthodontic force U. Baumert 1, I. Golan 1, M. Redlich 2, H.A. Roos2, A. Palmon 3, D. Muessig 1.
1Department of Orthodontics, University of Regensburg, Germany, 2Department of Orthodontics, and 3Institute of Dental Sciences, Hebrew University-Hadassah Faculty of Dental Medicine, Jerusalem, Israel Orthodontic force brings about remodellatory processes in the attachment apparatus, being mainly bone resorption on the pressure side and new bone formation on the tensions side. Mechanical loading affects the expression of RUNX2, the master gene of bone development and bone homeostasis. The objective of this study was to examine the effect of pressure type of force, simulating orthodontic force on RUNX2 and other genes' expression
$569 in osteoblasts. Using a stringent pulse-chase protocol human osteoblasts were exposed to centrifugal pressure force of varying durations. At defined times before and after pressure application, total RNA was isolated. Using quantitative real-time RT-PCR the gene expression levels of RUNX2 and other genes were measured. Immediately after 30 min of force application the RUNX2 gene expression was induced by a factor of 1.7±0.14 as compared to the negative control. This induction decreased rapidly and reached its pre-load levels within 30 min. A longer force application (up to 90 min) did not show any influence on the RUNX2 gene expression. Our results showed a clear transient increase in RUNX2 gene expression caused by mechanical pressure followed by a fast down-regulation back to its pre-load expression level. RUNX2 gene expression behavior after mechanical stimuli could be determined with a simple laboratory setup. In this pilot study only the duration of pressure was varied, which caused an immediate gene response. With the knowledge of each additional variable the use of standard values can be reduced when calculating individual optimized force applications.
Track 8
Computer-Assisted Surgery 7633 We-Th, no. 1 (P62) Orthosim, a telematic tool for the preoperative planning A. Oltra 1, R. Lafuente2, C. Atienza 1, I. Bermejo 1, C. Avila 1, T. Mosnier3, R. Dejoz1, J. Prat 1. 1Institute of Biomechanics of Valencia, Valencia, Spain,
2Adapting S.L., Valencia, Spain, 3Laborateire de BieM6canique ENSAM, Paris, France Nowadays there is a great number of Finite Element Models (FEM) developed by Biomechanical Research Groups which can help surgeons and implant designers to understand the behaviour of the human body and its interaction with implants. Furthermore, some of them are prepared to be customized to pathology and morphology of the patient as well as to implants and surgical protocols. However, all these models cannot be used by surgeons or implant designers without advanced technical knowledge. Orthosim is a service which hosts all these models and provides them to the key players related to orthopaedics without need of having specific knowledge or software. The simulation process follows the next steps. First of all, the user enters the service platform and introduces the input data, characteristics of the patient, pathology, implant and surgical protocol, then the service converts these parameters into a macro understandable by the simulation programme resident at the research centre, owner of the model. After the simulation, the service converts the results or output parameters supplied by the model into relevant information for the user, related to the biomechanical behaviour of joints and implants. The first model offered within this service is "Mywebspine.com", a service platform based on a highly sophisticated and clinically validated Finite Element Model (FEM) of the lumbar spine and different spine implants. This service optimises the design of lumbar spine implants by manufacturers and the evaluation of biomechanical situations by surgeons in short times and with high approximation to the real clinical situation. In the near future models of other human joints (hip, cervical spine, etc) of different Biomechanical Research Groups, and new implant catalogues from different manufacturers will be enclosed within the service. 6596 We-Th, no. 2 (P62) 3-D size and shape variation in the distal femur: effect of ethnicity, gender and osteoarthritis N. Rooney1, D. FitzPatrick 1, G. Lawlor 1, H. Ishibashi 2, J. Lee3. 1Department
of Mechanical Engineering, University College Dublin, Ireland, 2 Tokyo Metropolitan Geriatric Medical Centre, Tokyo, Japan, 3 DePuy Orthopaedics Inc., Warsaw, IN, USA Introduction: Success of Total Knee Arthroplasty (TKA) relies upon correct sizing and positioning of the prosthetic implants. Previous anthropometric studies of the distal femur have examined predominantly 1-D measurements from male Caucasian subjects, forming the basis of current prosthesis design. More recent studies have focussed on 2-D measurements, ethnicity, and osteoarthritis (OA) effects [1,2]. These studies collectively suggest an underlying morphological difference between groups. This study describes the 3-D measurement variations as related quantitatively to ethnicity, gender, and OA, in which shape differences can be better understood. Materials and Methods: 202 knees were reconstructed from CT-data, whereby 3-D surface models of their constituent bones were generated. 136 Japanese knees and 66 Caucasian knees were used, including male/female
tissues as viscoelastic continua. The loading conditions during clenching were given by the contraction forces of the masticatory muscles exerted during clenching. In the connective tissue surrounding the disc, the high stress/strain were observed mainly in the retrodiscal region. In particular, the retrodiscal tissue strain almost tripled with time by the continuous clenching. In addition, the anterior displacement of the disc increased with time also. The disc displacement in anterior direction was larger when the disc attachment area of the superior head of lateral pterygoid muscle (SLPM) was larger. These results confirmed that the continuous clenching is associated with the anterior disc displacement (ADD), and that the excessive activity of SLPM is a risk factor for ADD. 6965 We-Th, no. 17 (P62) Osseointegration of ceramic dental implants S. KSbel, O. Bothe, W. Weber. Metexit AG, Thayngen, Switzerland This study reviews osseointegration of ceramic dental implants. Latest results of the bone response to zirconia ceramic implants are also presented. Zirconia ceramic, i.e. Y-TZP, has a favourable combination of an excellent biocompatibility and high mechanical strength. Over the past years, several studies were conducted on osseointegration of zirconia dental implants. These studies are briefly reviewed and the performance and limitations of zirconia and titanium implants are compared. Recent results are presented showing that even after 4 to 6 weeks of healing zirconia implants reach high stability in the bone as determined by the resistance to torque forces. Histological and clinical studies support these findings. Zirconia ceramic implants show excellent performance and are therefore an excellent alternative to titantium implants for many indications. 6063 We-Th, no. 18 (P62) From quantum to biomechanics: improving the host response to implantable devices P.G. Coelho 1, J.E. Lemons 2, J. Nilo Freire3, A.L. Coelho4. 1Biomaterials and
Biomimetics, New York University, New York, NY, USA, 2 prosthodontics and Biomaterials, University of Alabama at Birmingham, Birmingham, AL, USA, 3private Practice, Florianepolis, Brazil, 4UNICENP, Curitiba, Brazil Nanotechnology has strongly affected biomaterials science, since reduced matter domains (quantum confined) may deeply alter its electronic/thermodynamic properties and thus the response of living tissues. This presentation focuses on a series of in-vitro and in-vive studies concerning controlled bioceramic surface engineering processes (ion beam assisted deposition - IBAD) which yielded Ca- and P-based coatings ranging from 300 to 5000 angstroms. The in-vitro studies comprised FESEM, EDS, ionmilling + XPS for depth profiling, ToF-SIMS, and thin-film XRD. Two animal studies comprised the in-vivo part of the series. The first in-vivo protocol was utilized for osseoactivity, osseointegration (bone to implant contact - BIC), and biomechanical fixation assessment of 300-500A bioceramic coatings versus a noncoated implant (control). The second animal model analyzed mineral apposition rates (MAR), osseointegration, and biomechanical fixation of 200500A bioceramic coated implants, 2000-5000A bioceramic coated implants, noncoated implants (control), and plasma sprayed HA (PSHA) coated implants. The in-vitro results showed that the nanothick coatings were of Ca- and P-basic composition and presented amorphous microstructures. In addition, coating stoichiometry varied as a function of coating depth. The first animal model showed that significantly higher osseoactivity levels were found for 200-500A bioceramic coated implants. The second animal investigation showed that 2000-5000A bioceramic coated implants and PSHA presented higher degrees of BIC and biomechanical fixation at 3 and 5 weeks in-vivo compared to other groups. MAR values presented complex patterns as time elapsed in-vivo, with 2000-5000A bioceramic coated implants and noncoated implants presenting higher values at 3 and 5 weeks in-vivo. According to this series of studies, it can be concluded that nanothick bioceramic coatings, if processed to a thickness of 2000-5000A, enhance the biological response of bone to implant to levels comparable to PSHA. 4409 We-Th, no. 19 (P62) Pressure simulation of orthodontic force U. Baumert 1, I. Golan 1, M. Redlich 2, H.A. Roos2, A. Palmon 3, D. Muessig 1.
1Department of Orthodontics, University of Regensburg, Germany, 2Department of Orthodontics, and 3Institute of Dental Sciences, Hebrew University-Hadassah Faculty of Dental Medicine, Jerusalem, Israel Orthodontic force brings about remodellatory processes in the attachment apparatus, being mainly bone resorption on the pressure side and new bone formation on the tensions side. Mechanical loading affects the expression of RUNX2, the master gene of bone development and bone homeostasis. The objective of this study was to examine the effect of pressure type of force, simulating orthodontic force on RUNX2 and other genes' expression
$569 in osteoblasts. Using a stringent pulse-chase protocol human osteoblasts were exposed to centrifugal pressure force of varying durations. At defined times before and after pressure application, total RNA was isolated. Using quantitative real-time RT-PCR the gene expression levels of RUNX2 and other genes were measured. Immediately after 30 min of force application the RUNX2 gene expression was induced by a factor of 1.7±0.14 as compared to the negative control. This induction decreased rapidly and reached its pre-load levels within 30 min. A longer force application (up to 90 min) did not show any influence on the RUNX2 gene expression. Our results showed a clear transient increase in RUNX2 gene expression caused by mechanical pressure followed by a fast down-regulation back to its pre-load expression level. RUNX2 gene expression behavior after mechanical stimuli could be determined with a simple laboratory setup. In this pilot study only the duration of pressure was varied, which caused an immediate gene response. With the knowledge of each additional variable the use of standard values can be reduced when calculating individual optimized force applications.
Track 8
Computer-Assisted Surgery 7633 We-Th, no. 1 (P62) Orthosim, a telematic tool for the preoperative planning A. Oltra 1, R. Lafuente2, C. Atienza 1, I. Bermejo 1, C. Avila 1, T. Mosnier3, R. Dejoz1, J. Prat 1. 1Institute of Biomechanics of Valencia, Valencia, Spain,
2Adapting S.L., Valencia, Spain, 3Laborateire de BieM6canique ENSAM, Paris, France Nowadays there is a great number of Finite Element Models (FEM) developed by Biomechanical Research Groups which can help surgeons and implant designers to understand the behaviour of the human body and its interaction with implants. Furthermore, some of them are prepared to be customized to pathology and morphology of the patient as well as to implants and surgical protocols. However, all these models cannot be used by surgeons or implant designers without advanced technical knowledge. Orthosim is a service which hosts all these models and provides them to the key players related to orthopaedics without need of having specific knowledge or software. The simulation process follows the next steps. First of all, the user enters the service platform and introduces the input data, characteristics of the patient, pathology, implant and surgical protocol, then the service converts these parameters into a macro understandable by the simulation programme resident at the research centre, owner of the model. After the simulation, the service converts the results or output parameters supplied by the model into relevant information for the user, related to the biomechanical behaviour of joints and implants. The first model offered within this service is "Mywebspine.com", a service platform based on a highly sophisticated and clinically validated Finite Element Model (FEM) of the lumbar spine and different spine implants. This service optimises the design of lumbar spine implants by manufacturers and the evaluation of biomechanical situations by surgeons in short times and with high approximation to the real clinical situation. In the near future models of other human joints (hip, cervical spine, etc) of different Biomechanical Research Groups, and new implant catalogues from different manufacturers will be enclosed within the service. 6596 We-Th, no. 2 (P62) 3-D size and shape variation in the distal femur: effect of ethnicity, gender and osteoarthritis N. Rooney1, D. FitzPatrick 1, G. Lawlor 1, H. Ishibashi 2, J. Lee3. 1Department
of Mechanical Engineering, University College Dublin, Ireland, 2 Tokyo Metropolitan Geriatric Medical Centre, Tokyo, Japan, 3 DePuy Orthopaedics Inc., Warsaw, IN, USA Introduction: Success of Total Knee Arthroplasty (TKA) relies upon correct sizing and positioning of the prosthetic implants. Previous anthropometric studies of the distal femur have examined predominantly 1-D measurements from male Caucasian subjects, forming the basis of current prosthesis design. More recent studies have focussed on 2-D measurements, ethnicity, and osteoarthritis (OA) effects [1,2]. These studies collectively suggest an underlying morphological difference between groups. This study describes the 3-D measurement variations as related quantitatively to ethnicity, gender, and OA, in which shape differences can be better understood. Materials and Methods: 202 knees were reconstructed from CT-data, whereby 3-D surface models of their constituent bones were generated. 136 Japanese knees and 66 Caucasian knees were used, including male/female