Study on internal structure of zygomatic bone using micro-finite element analysis model--differences between dentulous and edentulous dentition in Japanese cadavers.

The purpose of this study was to analyze changes in the internal structure of zygomatic bone using a micro-finite element analysis model (muFEA) and compare angular orientation of trabeculae against compressive force in edentulous and dentulous jaws. Twenty zygomatic bones from dentulous jaws and 20 zygomatic bones from edentulous jaws harvested from Japanese male cadavers were used. From 2-dimensional slice images, we reconstructed 3-dimensional (3D) structure by the volume rendering method using micro-computed tomography (micro-CT). To analyze mechanical properties, all voxels were converted to muFEA models. The angle between the strongest direction of trabecular bone and the axial loading direction (angle alpha) was then determined using the muFEA models. In the 3-D reconstruction images, trabecular density in dentulous jaws was higher than that in edentulous jaws at all loci. Trabeculae in dentulous jaws showed a plate-like structure. The muFEA modeling revealed that the angle of the trabeculae at the Jugale in edentulous jaws was lower than that in dentulous jaws. This suggests that the internal structure of trabeculae is influenced by occlusal force in zygomatic bone from edentulous jaws.

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study / Estudo morfológico comparativo do enxerto ósseo autógeno e polímero de mamona em rebordo infra-orbitário de coelhos

PURPOSE: Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits. METHODS: Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis. RESULTS: Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group. CONCLUSION: The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.

OBJETIVO: Estudo morfológico comparativo do implante de poliuretana de mamona e enxerto ósseo autógeno em defeito ósseo padrão em osso zigomático de coelhos. MÉTODOS: Vinte e quatro coelhos Nova Zelândia, machos, adultos, foram distribuídos aleatoriamente em dois grupos de 12. Defeitos de 5mm de diâmetro, perenes, foram confeccionados em osso zigomático e preenchidos com discos pré-fabricados de poliuretana no grupo experimento ou osso autógeno extraído da tíbia no grupo controle. Os animais foram sacrificados após 30, 60 e 90 dias e as peças anatômicas foram avaliadas macro e microscopicamente. Foram utilizados os testes de Student, Fisher,qui-quadrado e McNemar para a análise estatística dos resultados. RESULTADOS: A poliuretana e o osso autógeno se adaptaram ao defeito sem necessidade de fixação. Houve formação de tecido conjuntivo fibroso envolvendo a poliuretana, sem reação inflamatória ou presença de células gigantes. Verificaram-se áreas acidófilas e basófilas nos poros do material implantado, sugestivas de núcleos celulares. No grupo controle, observou-se aos 90 dias o reparo ósseo de padrão lamelar clássico. CONCLUSÃO: A poliuretana de mamona foi biocompatível e não causou reação inflamatória deletéria. Pode ser uma alternativa para o preenchimento de defeitos ósseos.

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study.

PURPOSE: Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits. METHODS: Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis. RESULTS: Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group. CONCLUSION: The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.

[Osteoclastoma of temporal and zygomatic bone]. / Guz olbrzymiokomórkowy kosci skroniowej i jarzmowej.

A twelve year boy was admitted to the Otolaryngological Clinic of the Medical Academy in Cracow with a paralysis of the peripheral facial nerve and a tumor on the right zygomatic arc. A CT investigation revealed an expansive process in the central fossa of the skull, which continuously passed into the squama of the temporal bone and the are of the zygomatic bone on the right side, causing a paralysis of the nerve VII. A neurosurgical intervention was carried out as well as a subsequent treatment by radiotherapy. A remission of the tumor was achieved. Osteoclastoma was diagnosed histologically.