ABSTRACT Objective: The aim of this study was to compare the stress distribution in internal tapered connection implants with different adaptation geometries submitted to oblique load simulation using the Finite Element Analysis (FEA) method. Methods: Three different internal tapered implant-abutment assemblies were modeled by varying only the diameter of the abutment body in the cone region. The dimensions of the implants were 4.0 mm in diameter and 13 mm in length. Oblique loads of 210 N angled 30 degrees to the long axis of the implant were applied to a hemispherical body positioned over the abutments simulating a dental crown. The stress generated by the implant-abutment assembly was analyzed by the FEA method using the von Mises criterion. Results: A higher concentration of stress in the coronal region (collar) and implant body on the opposite side of the load application was shown, as well as in the body region of the abutments and in the screw threads. The cervical region of the implants showed the highest von Mises stress values, the highest values being observed in G3 (1034 MPa), followed by G2 (841 MPa) and G1 (702 MPa). Conclusion: According to the results presented, it can be concluded that the stress distribution was more homogeneous and less concentrated in the G1 implant-abutment assembly. Therefore, the use of abutments with dimensions standardized by the implant manufacturer is recommended.

RESUMO Objetivo: O objetivo deste estudo foi comparar a distribuição de tensões em implantes de conexão cônica interna com diferentes geometrias de adaptação submetidos à simulação de carga oblíqua pelo método de Análise de Elementos Finitos (FEA). Métodos: Três diferentes conjuntos implante-pilar cônicos internos foram modelados variando apenas o diâmetro do corpo do pilar na região do cone. As dimensões dos implantes foram de 4,0 mm de diâmetro e 13 mm de comprimento. Cargas oblíquas de 210 N anguladas 30 graus em relação ao longo eixo do implante foram aplicadas sobre um corpo hemisférico posicionado sobre os pilares simulando uma coroa dentária. A tensão gerada pelo conjunto implante-pilar foi analisada pelo método FEA utilizando o critério de von Mises. Resultados: Foi evidenciada maior concentração de tensões na região coronal (colar) e corpo do implante no lado oposto da aplicação da carga, assim como na região do corpo dos pilares e nas roscas dos parafusos. A região cervical dos implantes apresentou os maiores valores de tensão de von Mises, sendo os maiores valores observados em G3 (1034 MPa), seguido de G2 (841 MPa) e G1 (702 MPa). Conclusão: De acordo com os resultados apresentados, pode-se concluir que a distribuição de tensões foi mais homogênea e menos concentrada no conjunto implante-pilar do G1. Portanto, recomenda-se o uso de pilares com dimensões padronizadas pelo fabricante do implante.

Abstract Objective This study aimed to retrospectively collect clinical data to evaluate the influence of possible risk factors on the long-term success of implant treatment with extra-narrow (2.9 mm diameter) implants in a daily dental practice setting. Methodology Data were collected from records of patients who received at least one extra-narrow implant from 2012 to 2017, regarding implant survival, prosthesis survival, patient characteristics, and implant characteristics. The association between the dependent variables “implant survival”, “prosthesis survival,” and “adverse events” related to patient and implant characteristics was statistically evaluated by chi-square tests. Moreover, implant and prosthesis survival were analyzed by Kaplan-Meier survival curves. Results The sample was constituted of 58 patients (37 women and 21 men) with a mean age of 54.8 years old (SD: 12.5), followed up for up to eight years. In total, 86 extra-narrow implants were placed within this sample. Four implants were lost, resulting in an implant survival rate of 95.3%. A total of 55 prostheses were inserted and only one (1.8%) was lost, resulting in a prosthesis survival rate of 98.2%. The mean implant and prosthesis survival time was, respectively, 7.1 years and 6.3 years, according to the Kaplan-Meier survival analysis. A correlation was found between smoking and implant loss, which makes implant loss eight times more likely to occur in smokers than non-smokers. A significant association was also found between prosthesis loss and previous need of prosthesis repair. However, it was not considered clinically relevant. No association was found between the occurrence of adverse events and later implant or prosthesis loss. Conclusion High implant and prosthesis survival rates were found in the long term for treatment with extra-narrow implants. Moreover, a significant correlation between smoking and implant loss was observed.

RESUMO O planejamento preciso para a instalação de implantes dentários requer a apreciação das limitações anatômicas e objetivos restaurativos. O diagnóstico pode ser feito por exames complementares, como radiografia panorâmica e tomografia computadorizada de feixe cônico. O objetivo deste estudo foi reabilitar, a mandíbula superior e inferior de um paciente com doença periodontal severa, utilizando uma osteotomia guiada e implantes cone Morse instalados com as mãos livres. O conceito de cirurgia guiada foi utilizado para preparar o osso alveolar para a instalação de oito implantes, quatro implantes no maxilar superior e quatro implantes no maxilar inferior, todos alcançando um torque mínimo de 60 Ncm. A técnica de sutura modificada foi utilizada para melhor estabilizar o tecido mole ao redor dos mini-pilares cônicos. Os abutments foram escaneados por CAD/CAM para confecção das estruturas metálicas das próteses dentárias. No terceiro dia, as próteses de arco superior e inferior foram instaladas e os contatos bilaterais simultâneos foram ajustados. Após 12 meses de acompanhamento do paciente, os implantes e próteses estavam em boas condições de estética e função, mantendo o sucesso da reabilitação. Dentro das limitações deste caso clínico, pode-se concluir que os implantes instalados com as mãos livres foram facilitados pelo uso prévio da osteotomia guiada.

ABSTRACT Precise planning for dental implant placement requires appreciation of anatomical limitations and restorative purpose. Diagnosis can be made by complementary exams such as panoramic radiography and cone-beam computed tomography. The purpose of this study was to rehabilitate the upper and lower jaw of a patient with severe periodontal disease using a guided osteotomy and implants placed with free hands and Morse taper implants. The concept of guided surgery was used to prepare the alveolar bone to place eight implants, four implants in the upper jaw and four implants in the lower jaw, all have achieved a minimum torque of 60 Ncm. The modified suture technique was used to better stabilize the soft tissue around the mini conical abutments. The analogues were scanned by CAD/CAM for confection of the metallic structures of the bridges. On the third day, the upper and lower full arch prostheses were installed and simultaneous bilateral contacts were adjusted. After 12 months of patient follow-up, the implants and prostheses were in good condition of aesthetics and function, maintaining the success of the rehabilitation. Within the limitations of this clinical case, it can be concluded that the implants placed with free hands was facilitated by a previous guided osteotomy.