FEA of Peri-Implant Stresses in Fixed Partial Denture Prostheses with Cantilevers.

PURPOSE: To compare stresses in the peri-implant bone produced by fixed partial prostheses with mesial and distal cantilevers, when cemented or screwed onto implants. MATERIALS AND METHODS: The experimental design consisted of four 3D models obtained by volumetric computerized tomography and analyzed using finite element analysis (FEA). Stresses were simulated in two stages. Stage 1 consisted of application of the preload. A 288 N load was applied to pillar screws of the cemented prosthesis, resulting in 389 MPa peak; 257 N was applied to the intermediate screw (multi-unit) resulting in 390 MPa peak; and 111 N was applied to the prosthesis infrastructure screw in the screwed prostheses, resulting in 390 MPa peak. In stage 2, the axial and oblique loads were applied. The axial load consisted of 50 N for molar implants and 30 N for premolar implants. The oblique load (on the buccal slope of the buccal cusp of each crown) consisted of 30 N for premolar implants and 50 N for molar implants, with a buccolingual vector at a 45° angle with the occlusal plane. The response variables were the axial and oblique stresses on the peri-implant bone, according to the following groups: group 1-models of fixed partial prostheses cemented onto implants with mesial or distal cantilevers; group 2-models of fixed partial denture screwed onto implants with mesial or distal cantilevers. Data were recorded, evaluated, and compared. RESULTS: Oblique loads produced higher peak values than axial loads, and were located at the bone crest of the implant closest to the cantilever, regardless of the prosthesis type. In the cemented prosthesis models, oblique loads produced the highest peaks in the primary implant region when compared with the screwed prosthesis models. CONCLUSION: The screwed fixed prostheses caused less stress on peri-implant bone regardless of whether the cantilever was located mesially or distally.

Ressecção de ameloblastoma utilizando prototipagem - relato de caso / Ressection of ameloblastoma using prototyping - case report

Introdução: O ameloblastoma é uma neoplasia benignacomposta de epitélio odontogênico sem a participação deectomesênquima odontogênico, representando 1% dos tumoresmaxilares e 11% de todos os tumores odontogênicos. A melhorforma de tratamento vem sendo motivo de controvérsias há váriosanos. A ressecção segmentar ou a parcial produz bons resultados,especialmente quando realizada como tratamento principal. Umavez que a lesão infiltra nos tecidos moles circundantes, a taxade recidiva aumenta. A prototipagem rápida (PR) consiste emum grupo de processos utilizados para produzir objetos em trêsdimensões pela adição de camadas de material. Os biomodelosde PR são protótipos biomédicos obtidos a partir de imagensde tomografia computadorizada (TC), ressonância magnética eultra-sonografia, podendo ser utilizados com objetivos didáticos,na fabricação de implantes protéticos personalizados, nodiagnóstico precoce e, tratamento de deformidades. Isto tende areduzir o tempo do procedimento cirúrgico e, consequentemente,o período de anestesia, bem como o risco de infecção, havendoainda melhora no resultado e a diminuição no custo global dotratamento. Objetivo: Descrever um caso de ressecção deameloblastoma utilizando a prototipagem rápida no planejamentocirúrgico. Relato de caso: Paciente do sexo masculino, 23 anos,com diagnóstico de ameloblastoma na mandíbula, submetidoa ressecção da lesão com planejamento prévio por meio deprototipagem. Conclusão: A utilização da prototipagem é umótimo recurso a ser utilizado para planejamento de cirurgias docomplexo maxilo-facial, principalmente em lesões agressivascomo o ameloblastoma, que necessitam de uma avaliaçãocriteriosa e um bom planejamento.

Evaluación de la resistencia a la tracción de tres dispositivos ortodóncicos instalados con resina autopolimerizable en premolares: un estudio in vitro / Evaluation of the tensile strength of three orthodontic devices installed with self-curing resin in premolars: an in vitro study

Las tracciones orto-quirúrgicos son técnicas ampliamente utilizadas en odontología para la reposición en oclusión de dientes que incluidos. Nuestro objetivo fue evaluar la resistencia a la tracción de tres tipos de dispositivos de tracción. En este estudio in vitro fueron utilizados 45 premolares sanos, conservados inicialmente en suero fisiológico al 0,9%; fueron divididos en tres grupos, de los cuales 15 recibieron la instalación de brackets, 15 recibieron botones ortodóncicos y 15 recibieron la instalación de mallas. La adhesión fue realizada con resina de autocurado y en todos ellos se instaló un alambre ortodóncico de 0,30mm; los dientes fueron fijados con resina acrílica y almacenados en suero fisiológico al 0,9% por 72 horas. A continuación fueron sometidos a test de tracción mecánica, con una tracción máxima de 50N, siendo analizados con del programa Logger Pro®. Los brackets demostraron mayor resistencia a la tracción (44,6N), seguidos por los botones y finalmente por las mallas (32N). La principal área de falla fue la interface dispositivo/resina, siendo las mallas las que presentaron el mayor índice de fracaso (66%). Ningún alambre presentó ruptura en los análisis ejecutados. Las mallas presentan los resultados mecánicos más pobres cuando son comparados con botones y brackets; el área de ruptura más frecuente corresponde a la interface dispositivo/resina

Ortho-surgical tractions are techniques very used in dentistry for the reposition in occlusion of embedded teeth. The aim of this research was to evaluated the resistance to traction of three kind of devices used in a traction technique. In this in vitro research was used 45 bicuspid, initially maintained in saline solution (0,9%); were formed three groups, where 15 received brackets, 15 received button and 15 received mesh. The adhesion was do it with self-curing resin and in all of them was installed an orthodontics wire of 0,30 mm; the teeth was fixed with acrylic resin and maintained in saline solution (0,9%) for 72 hours. Follow that, the samples were submitted to mechanical traction test, with maximum traction of 50N, being analyzed with Logger Pro software. The brackets show more resistance to the traction (44,6N), follow that button and finally for mesh (32N). The principal areas of fracture was to device/resin interface, presented the mesh a more failure percentage (66%). Non wire presented fracture in the analyses. The mesh present poor results when compared to buttons and brackets; the more prevalent area failure was device/resin interface