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Judgement of irradiated periimplant soft and hard tissue attachment in endosseous orbital implants
P23-1 Preprosthetic surgery and impIantology P23-1 Preprosthetic surgery and implantology
1. Judgement of irradiated periimplant soft and hard tissue attachment in endosseous orbital implants
Tveten, S., Weischer T., Mohr, Chr. Department of Oral and MaxilIofacial Surgery, University of Essen, Essen, Germany After exenteratio orbitae and high dose irradiation (60 Gy on average) 17 endosseous implants were placed periorbitally in five patients. No hyperbaric oxygen therapy was performed. All implants were primary covered with regional dr free flaps. After second stage surgery pocket depth, periotest and soft tissue were examined in short recall intervals and occipitonasomental radiograph made. At implant uncovering, all fixtures were osseointegrated. After an average control period of 35 months no fixture had failed. In two patients peri-implant inflammation caused by staphylococcus aureus occurred, which were clinically only determined by soft tissue oedema and hyperaemia. The results show that a primary soft tissue covering seems to be essential for implant osseointegration in the irradiated orbita. For evalution of a beginning peri-implant inflammation the clinical assessment of the peri-implant soft tissue including a microbiological diagnosis is mandatory in order to avoid implant failure.
2. Finite Element Analysis of Stress Distribution around Dental Implants - Part II: New multi-post implants
Lai, D. R. 1'2, Kamishiro, A. l, Tsai, C. C.2, Murase, K. 3, Tsutsumi, S. 3 1International APEX Oral Clinic Research Center, 2School of Dentistry, Graduate Institute of Dentistry, Kaohsung Medical College, Taiwan, 3Research Center for Biomedical Engineering, Kyoto University, Japan The improvement of dental implantology has broadened the spectrum of clinical applications. The implant fixation at the bone interface may not always be enough in response to the loading conditions, the bone volume around the implant, and the diameter of the dental implant. Micromotion caused by incomplete fixation is a key factor in implant failures. The purpose of this study is to investigate the stress distribution and stability at the neck and apex regions of the interfaces between bone and our newly designed dental implant (Multi-Post Implant) using 3-Dimensional finite element analysis (3D-FEA). Two models of dental implants were compared. The first was a conventional s!ngle implant (150 mm in length, 3.6 mm in diameter). The second was a new multi-post implant (two posts: 150 mm in length, 1.8 mm in diameter). 3D-FEA software (COSMOS/M Ver.l.75, Yokokawa Inc.) was used for analysis of clinical simulations. An oblique loading of 50N was applied to the tip of the implant. The results of the
231
analyses were able to be visualized with any slice on AVS (Kubota Computer Inc.) for comparison of compressive stress and displacement of models. The maximum displacement of the Multi-Post model was reduced by about 50% compared with that of the single implant model. The compressive stress at the neck region of the cancellous bone was decreased more than that of the single model. These results indicated that the Multi-Post Implant has better support against compressive loading and suggested that the Multi-Post Implant has a more effective unit system for the significant improvement in micromotion under ocelusal loading.
3. Clinical and Histopathological Comparison of Two Bladevent Implants - Sumicikon and Shape Memory Implant
Chang, H.-H., Chen, H.-M., Kok, S.-H., Hong, C.-Y, Wang, J.-T., Kuo, Y.-S. Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan The purpose of the study is to investigate the clinical performance and histopathological reaction of two blade-vent implants, Sumicikon and Shape Memory Implant (SMI). Six adult Taiwanese monkeys (Macaca cyclopis) were used in the study. Their mandibular molars of both sides were extracted and the sockets were allowed to heal for 5 months. Then one Sumicikon or SMI was implanted into each of the edentulous areas. Either a free-standing crown or bridge connecting the implant to the second premolar was made. Within 2-3 weeks postoperatively, the superstructures were cemented to the abutments after adjustment to obtain proper occlusal contacts. The animals were led with solid monkey chow and no oral hygiene measures were taken. Three years after loading, it was found that all implants restored with bridges and Sumicikons restored with free-standing crowns were stable while the surrounding gingiva was clinically healthy. Radiological and histological examinations revealed no peri-implant bone resorption. However, SMIs restored with freestanding crowns showed less satisfactory results. It was concluded that Sumicikons were suitable for both free-standing crown restoration and bridge connected with nature teeth, whereas SMIs performed well only when connected with adjacent teeth.
4. The Relationship Between Radiation Dosage and Hyperbaric Oxygen Therapy with Respect to Bone Reaction around Hydroxyapatite Implants
Chen, X., Matsui, Y, Kudo, M., Ohno, K., Miehi, If. Department of OMS, School of Dentistry, Showa Univ., Tokyo, Japan An increasing number of irradiated patients are being treated with osseointegrated implants to restore their orofa-
1. Judgement of irradiated periimplant soft and hard tissue attachment in endosseous orbital implants
Tveten, S., Weischer T., Mohr, Chr. Department of Oral and MaxilIofacial Surgery, University of Essen, Essen, Germany After exenteratio orbitae and high dose irradiation (60 Gy on average) 17 endosseous implants were placed periorbitally in five patients. No hyperbaric oxygen therapy was performed. All implants were primary covered with regional dr free flaps. After second stage surgery pocket depth, periotest and soft tissue were examined in short recall intervals and occipitonasomental radiograph made. At implant uncovering, all fixtures were osseointegrated. After an average control period of 35 months no fixture had failed. In two patients peri-implant inflammation caused by staphylococcus aureus occurred, which were clinically only determined by soft tissue oedema and hyperaemia. The results show that a primary soft tissue covering seems to be essential for implant osseointegration in the irradiated orbita. For evalution of a beginning peri-implant inflammation the clinical assessment of the peri-implant soft tissue including a microbiological diagnosis is mandatory in order to avoid implant failure.
2. Finite Element Analysis of Stress Distribution around Dental Implants - Part II: New multi-post implants
Lai, D. R. 1'2, Kamishiro, A. l, Tsai, C. C.2, Murase, K. 3, Tsutsumi, S. 3 1International APEX Oral Clinic Research Center, 2School of Dentistry, Graduate Institute of Dentistry, Kaohsung Medical College, Taiwan, 3Research Center for Biomedical Engineering, Kyoto University, Japan The improvement of dental implantology has broadened the spectrum of clinical applications. The implant fixation at the bone interface may not always be enough in response to the loading conditions, the bone volume around the implant, and the diameter of the dental implant. Micromotion caused by incomplete fixation is a key factor in implant failures. The purpose of this study is to investigate the stress distribution and stability at the neck and apex regions of the interfaces between bone and our newly designed dental implant (Multi-Post Implant) using 3-Dimensional finite element analysis (3D-FEA). Two models of dental implants were compared. The first was a conventional s!ngle implant (150 mm in length, 3.6 mm in diameter). The second was a new multi-post implant (two posts: 150 mm in length, 1.8 mm in diameter). 3D-FEA software (COSMOS/M Ver.l.75, Yokokawa Inc.) was used for analysis of clinical simulations. An oblique loading of 50N was applied to the tip of the implant. The results of the
231
analyses were able to be visualized with any slice on AVS (Kubota Computer Inc.) for comparison of compressive stress and displacement of models. The maximum displacement of the Multi-Post model was reduced by about 50% compared with that of the single implant model. The compressive stress at the neck region of the cancellous bone was decreased more than that of the single model. These results indicated that the Multi-Post Implant has better support against compressive loading and suggested that the Multi-Post Implant has a more effective unit system for the significant improvement in micromotion under ocelusal loading.
3. Clinical and Histopathological Comparison of Two Bladevent Implants - Sumicikon and Shape Memory Implant
Chang, H.-H., Chen, H.-M., Kok, S.-H., Hong, C.-Y, Wang, J.-T., Kuo, Y.-S. Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan The purpose of the study is to investigate the clinical performance and histopathological reaction of two blade-vent implants, Sumicikon and Shape Memory Implant (SMI). Six adult Taiwanese monkeys (Macaca cyclopis) were used in the study. Their mandibular molars of both sides were extracted and the sockets were allowed to heal for 5 months. Then one Sumicikon or SMI was implanted into each of the edentulous areas. Either a free-standing crown or bridge connecting the implant to the second premolar was made. Within 2-3 weeks postoperatively, the superstructures were cemented to the abutments after adjustment to obtain proper occlusal contacts. The animals were led with solid monkey chow and no oral hygiene measures were taken. Three years after loading, it was found that all implants restored with bridges and Sumicikons restored with free-standing crowns were stable while the surrounding gingiva was clinically healthy. Radiological and histological examinations revealed no peri-implant bone resorption. However, SMIs restored with freestanding crowns showed less satisfactory results. It was concluded that Sumicikons were suitable for both free-standing crown restoration and bridge connected with nature teeth, whereas SMIs performed well only when connected with adjacent teeth.
4. The Relationship Between Radiation Dosage and Hyperbaric Oxygen Therapy with Respect to Bone Reaction around Hydroxyapatite Implants
Chen, X., Matsui, Y, Kudo, M., Ohno, K., Miehi, If. Department of OMS, School of Dentistry, Showa Univ., Tokyo, Japan An increasing number of irradiated patients are being treated with osseointegrated implants to restore their orofa-