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Abstract:The tissue reaction of bone tissue accessed by light microscopy and scanning electron microscopy (SEM) images after polyurethane resin implantation is presented in this study. Twenty four male rabbits were used, divided into two groups of 12 animals each (experimental group and control group) in which full-thickness cranial defect was surgically created. At 30 and 90 days post operation 6 animals of each group were euthanized and bone samples were removed for analysis. The microscopic results indicated no inflammatory foreign body reaction, a perfect union between the polymer and surgical bone bed surface, lack of bone resorption and presence of a thin layer of osteogenic material covering the polymer surface in contact with the surgical bone bed. The SEM images demonstrate the porosity of the resin, with diameters from 120 to 500 µm. This important feature of this polymer is associated with its osteoconductivity, allowing the bone growth inside it, improving the integration between the material and bone tissue. These results confirm that polyurethane resin derived from Ricinuscommunis is an excellent bone substitute for use in repair surgery for great bone losses.

ResumoIntrodução: Quando os níveis de tensão e compressão gerados no sistema osso-implante excederem a capacidade óssea ocorre uma fadiga mecânica, resultando em colapso e perda da osseointegração. Objetivo: Analisar o comportamento biomecânico em próteses unitárias implanto-suportadas com implantes de diferentes diâmetros na região posterior de mandíbula. Material e método: Foram criados três modelos de elementos finitos de implantes cone-Morse de mesmo comprimento, variando-se o diâmetro: 3,3 mm, 4,1 mm e 4,8 mm. A localização do implante foi a região de primeiro molar inferior, com componente e coroa protética sobrejacentes. A mandíbula foi composta por osso cortical e medular. Foi criada malha refinada de 0,5 mm nas interfaces criticas a serem analisadas. O carregamento dos modelos foi realizado nos pontos de contatos oclusais, com uma carga oclusal de 400 N. Resultado: Tensão e deformação máximas ocorreram nas regiões cervicais dos implantes em todos os grupos, tanto na análise dos implantes e componentes quanto na análise do osso cortical. Quanto maior foi o diâmetro, menores foram tensão e deformação encontradas no implante. O grupo 3,3 mm apresentou a maior deformação em osso cortical periimplantar, tendo o grupo 4,1 mm a menor deformação, significantemente menor em relação ao grupo 4,8 mm. Conclusão: Apesar de o implante de maior diâmetro (4,8 mm) ter apresentado os menores valores de tensão e deformação, o grupo do implante de diâmetro intermediário (4,1 mm) mostrou menor taxa de deformação em osso cortical periimplantar. Portanto conclui-se que o implante de plataforma 4,1 mm apresentou-se mais efetivo biomecanicamente para manutenção óssea periimplantar.Descritores: Biomecânica; implante dental; análise por elementos finitos. AbstractIntroduction: When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective: Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method: Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm). The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result: Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion: Alth...

The purpose of this work was to evaluate the shear bond strength of resin composite to enamel treated with Er:YAG laser. It was used 33 human third molars. After the dental crowns cutting, the mesial and distal surfaces were embedded perpendicularly to the PVC cylinders long axis. Enamel was ground and the samples were randomly divided into 6 groups: G1- phosphoric acid (control), G2- Er:YAG laser (60mJ/10Hz), G3- Er:YAG (100mJ/10Hz), G4- Er:YAG (60mJ/10Hz + acid), G5- Er:YAG (100mJ/ 10Hz + acid), G6- Er:YAG (80mJ/2Hz). In all groups, Single Bond was used and resin composite cylinders (Z100) were prepared. The samples were stored in distilled water at 37oC for 24 hours and submitted to shearing test. G1 presented bond strength values significantly higher than G2, G3 and G6. The groups irradiated only with Er:YAG laser, in different intensities and frequencies, were equivalent as for the bond strength values. The groups treated with laser + acid presented strength values statistically equal to those of the control group. The enamel treatment with phosphoric acid, or its association with laser, is important to obtain good bond. The use of Er: YAG laser alone is not recommended, considering the conditions tested in this study.