Purpose: The aim of the present study was to use finite elemental analysis (FEA) to evaluate bone stress near an implant placed at the border between the mandible and fibular graft in mandibular reconstruction. Materi...Purpose: The aim of the present study was to use finite elemental analysis (FEA) to evaluate bone stress near an implant placed at the border between the mandible and fibular graft in mandibular reconstruction. Materials and Methods: A fibular model (FM) and transplantation model (TM) were constructed for FEA. In TM, mandible was on the mesial side and the fibular graft was on the distal side. The implant was positioned at the center of both bone models. In TM, it was placed on the border between the mandible and fibular graft. A 10-mm implant was used in the monocortical model and a 15-mm implant was used in the bicortical model. The loading force was set at 100 N, the angle was set at 90°, and the loading position was set as center, mesial, or distal on the upper surface of the prosthesis. Von Mises equivalent stress values of the bone near the implant collar and apex at the middle line between buccal and lingual side were measured. Results: In all models, stress values were significantly lower with center loading than with distal loading and mesial loading. In center loading, the stress values were significantly lower in the bicortical model than in the monocortical model. There were no significant differences in stress values between FM and TM in all conditions. Conclusions: Bone stress was least with the center loading position, which was further decreased by bicortical fixation. There was no increase in mechanical stress associated with placing an implant at the border between the mandible and the fibular graft.展开更多
Soft tissues are important for aesthetic considerations in implant therapy. The purpose of this study was to investigate soft tissue augmentation by using porous poly-DL-lactic acid (PDLLA)shaped as a tablet, with a d...Soft tissues are important for aesthetic considerations in implant therapy. The purpose of this study was to investigate soft tissue augmentation by using porous poly-DL-lactic acid (PDLLA)shaped as a tablet, with a diameter of5.0 mmand a height of2.0 mm. Porous PDLLA was implanted between the periosteal and epithelial tissues in 25 rats that were sacrificed at 1, 2, 4, 12, and 24 weeks. The average height of the PDLLA scaffolds at approximately 24 weeks was 1.85 ±0.08 mm, and the molecular weight decreased with time. Sinusoidal capillaries at 1 week, connective tissues at 4 weeks, and necrotic tissues at 24 weeks were observed more than other periods. At 24 weeks, the connective tissue surviving in the pores was confirmed to contain blood vessels;therefore, blood vessels are considered to be critical for the survival of soft tissue in scaffold pores. In this study, PDLLA was found to be useful for soft tissue augmentation in the long term. Although the molecular weight of PDLLA decreased with time, the height of the PDLLA scaffolds was preserved. The connective tissue surviving in the pores of the scaffolds at 24 weeks were associated with blood vessels. Further studies are necessary to investigate the optimal scaffold shape and surface characteristics to improve the penetration of blood vessels.展开更多
文摘Purpose: The aim of the present study was to use finite elemental analysis (FEA) to evaluate bone stress near an implant placed at the border between the mandible and fibular graft in mandibular reconstruction. Materials and Methods: A fibular model (FM) and transplantation model (TM) were constructed for FEA. In TM, mandible was on the mesial side and the fibular graft was on the distal side. The implant was positioned at the center of both bone models. In TM, it was placed on the border between the mandible and fibular graft. A 10-mm implant was used in the monocortical model and a 15-mm implant was used in the bicortical model. The loading force was set at 100 N, the angle was set at 90°, and the loading position was set as center, mesial, or distal on the upper surface of the prosthesis. Von Mises equivalent stress values of the bone near the implant collar and apex at the middle line between buccal and lingual side were measured. Results: In all models, stress values were significantly lower with center loading than with distal loading and mesial loading. In center loading, the stress values were significantly lower in the bicortical model than in the monocortical model. There were no significant differences in stress values between FM and TM in all conditions. Conclusions: Bone stress was least with the center loading position, which was further decreased by bicortical fixation. There was no increase in mechanical stress associated with placing an implant at the border between the mandible and the fibular graft.
文摘Soft tissues are important for aesthetic considerations in implant therapy. The purpose of this study was to investigate soft tissue augmentation by using porous poly-DL-lactic acid (PDLLA)shaped as a tablet, with a diameter of5.0 mmand a height of2.0 mm. Porous PDLLA was implanted between the periosteal and epithelial tissues in 25 rats that were sacrificed at 1, 2, 4, 12, and 24 weeks. The average height of the PDLLA scaffolds at approximately 24 weeks was 1.85 ±0.08 mm, and the molecular weight decreased with time. Sinusoidal capillaries at 1 week, connective tissues at 4 weeks, and necrotic tissues at 24 weeks were observed more than other periods. At 24 weeks, the connective tissue surviving in the pores was confirmed to contain blood vessels;therefore, blood vessels are considered to be critical for the survival of soft tissue in scaffold pores. In this study, PDLLA was found to be useful for soft tissue augmentation in the long term. Although the molecular weight of PDLLA decreased with time, the height of the PDLLA scaffolds was preserved. The connective tissue surviving in the pores of the scaffolds at 24 weeks were associated with blood vessels. Further studies are necessary to investigate the optimal scaffold shape and surface characteristics to improve the penetration of blood vessels.
