A finite element analysis was used to compare the effect of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible. Four models of an human mandible were constructed. In the OR (O'ring) group, the mandible was restored with an overdenture retained by four unsplinted implants with O'ring attachment; in the BC (bar-clip) -C and BC groups, the mandibles were restored with overdentures retained by four splinted implants with bar-clip anchor associated or not with two distally placed cantilevers, respectively; in the FD (fixed denture) group, the mandible was restored with a fixed full-arch four-implant-supported prosthesis. Models were supported by the masticatory muscles and temporomandibular joints. A 100-N oblique load was applied on the left first molar. Von Mises (σvM), maximum (σmax) and minimum (σmin) principal stresses (in MPa) analyses were obtained. BC-C group exhibited the highest stress values (σvM=398.8, σmax=580.5 and σmin=-455.2) while FD group showed the lowest one (σvM=128.9, σmax=185.9 and σmin=-172.1). Within overdenture groups, the use of unsplinted implants reduced the stress level in the implant/prosthetic components (59.4% for σvM, 66.2% for σmax and 57.7% for σmin versus BC-C group) and supporting tissues (maximum stress reduction of 72% and 79.5% for σmax, and 15.7% and 85.7% for σmin on the cortical and trabecular bones, respectively). Cortical bone exhibited greater stress concentration than the trabecular bone for all groups. The use of fixed implant dentures and removable dentures retained by unsplinted implants to rehabilitate edentulous mandible reduced the stresses in the periimplant bone tissue, mucosa and implant/prosthetic components.

The aim of this study was to determine the optimal thickness of reliner material that provides the least amount of stress on thin mucosa and supporting bone in patients with complete removable dentures using a three-dimensional finite element analyses. The model was obtained from two CT scans of edentulous mandibles with dentures supported by the alveolar ridge. After virtual reconstruction, the three-dimensional models were exported to the solidworks cad software and divided into six groups based on the thickness of the reliner material as follows: (i) without material, (ii) 0·5 mm, (iii) 1 mm, (iv) 1·5 mm, (v) 2 mm and (vi) 2·5 mm. The applied load was 60 N and perpendicular to the long axis of the alveolar ridge of all the prosthetic teeth, and the mucosal thickness used was 1 mm. The analyses were based on the maximum principal stress in the fibromucosa and the minimum principal stress in the basal bone. Stress concentration was observed in the anterior zone of the mandible in the mucosa and in the bone. The maximum and minimum principal stress in the mucosa and bone, respectively, decreased, whereas the thickness of the reliner material increased until 2 mm, which transmitted the lowest stress, compared with the control. Reliner materials with a thickness of 2·5 mm showed higher stress values than those with a thickness of 2 mm. In conclusion, reliner material with a thickness of 2 mm transmitted the lowest amount of stress to the mucosa and bone in 1 mm of mucosa thickness.

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Objetivo: este trabalho tem como finalidade apresentar um caso clínico de reabilitação oclusal protética com protocolo imediato por meio de cirurgia convencional, porém com técnica de alta previsibilidade, preservando o perfil gengival e papilas. Relato de caso: a paciente procurou atendimento odontológico com queixa estética dos dentes superiores, sendo que estes estavam desalinhados no arco (má oclusão) e dentes posteriores com perda de suporte e com doença periodontal avançada. O plano de tratamento proposto foi a confecção de uma prótese fixa sobre implantes imediatos (Protocolo Provisório). Para isso, foi necessário confeccionar uma prótese removível total imediata (PRTI). Esta deu origem ao Guia Cirúrgico Multifuncional, o qual serviu para instalação dos implantes e a transferência das suas posições para concluir o modelo de trabalho. Transcorrido essas etapas, a paciente foi submetida às exodontias de todos os dentes superiores e a instalação imediata dos implantes. Logo após, iniciou-se a sequência de confecção do protocolo provisório que foi parafusado, torque de 10 N, sobre os mini-pilares cônicos na mesma seção. A técnica preservou o perfil gengival e papilas. Após 8 meses da cirurgia inicial e passado o tempo de remodelação óssea, verificou-se a manutenção do perfil gengival que foi mantida para a confecção da Prótese Protocolo Definitiva. Considerações finais: pode-se concluir que a utilização da técnica de implantes imediatos preservando o perfil gengival na confecção de protocolos é uma boa alternativa para reabilitação oral, visto que apresenta um resultado estético favorável, quando é executada de forma precisa e correta.