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OBJETIVO: os rápidos e contínuos avanços nas Ciências da Computação resultaram no aumento significativo do emprego de novas tecnologias em todos os níveis da sociedade. Na Ortodontia, radiografias e fotografias digitais já são usadas de forma rotineira. A utilização de modelos de estudo digitais vem sendo anunciada como o novo componente da documentação ortodôntica computadorizada. Como acontece quando uma nova tecnologia se torna disponível, o uso de modelos ortodônticos digitais tem gerado controvérsias. Alguns ortodontistas questionam a aplicabilidade de imagens tridimensionais em substituição aos modelos tradicionais de gesso, pois não há na literatura número relevante de estudos que tenham testado adequadamente tal tecnologia. Diante disso, o objetivo desse estudo foi testar a confiabilidade do uso de modelos dentários digitais como exame complementar ao diagnóstico ortodôntico. METODOLOGIA: três examinadores mediram a largura dos dentes permanentes, quatro segmentos dos arcos superiores e inferiores, distâncias intercaninos, distâncias intermolares, trespasses horizontal e vertical em modelos de gesso e em seus correspondentes digitais de seis pacientes, utilizando um paquímetro digital e o programa eModel, respectivamente. RESULTADOS E CONCLUSÕES: diante dos resultados, observou-se que todas as medidas avaliadas foram estatisticamente semelhantes nos dois tipos de modelos testados, com exceção das médias encontradas para a largura do dente 45 (p<0,05). Entretanto essa diferença é considerada clinicamente aceitável. Comprova-se com esse estudo a confiabilidade do uso dos modelos dentários digitais como exame complementar ao diagnóstico ortodôntico. Além disso, a facilidade de armazenamento de informações, o menor risco de perda de dados durante sua manipulação e transporte, bem como a diminuição do tempo gasto para realizar as medições foram considerados vantagens do uso dessa nova tecnologia na Ortodontia.

Objective: To test the null hypothesis that enamel deproteinization with 10% papain gel does not increase the shear bond strength of orthodontic brackets bonded with resin-modified glass ionomer cement (RMGIC). Materials and Methods: One hundred and twenty bovine incisors were used and divided into eight groups: 1) Transbond XT according to the manufacturer's recommendations, 2) Transbond XT deproteinized with 10% papain gel, 3) RMGIC without enamel deproteinization and without etching, 4) RMGIC without enamel etching and with deproteinization with 10% papain gel, 5) RMGIC deproteinized with 10% papain gel and etched with polyacrylic acid, 6) RMGIC deproteinized with 10% papain gel and etched with phosphoric acid, 7) RMGIC deproteinized with 2.5% sodium hypochlorite, and 8) RMGIC etched with polyacrylic acid. After bonding, the mechanical tests were performed in a Universal mechanical test machine. The values obtained were submitted to an analysis of variance and afterward to the Tukey test (P , .05). Results: It was demonstrated that group 2 presented the highest shear bond strength value, and this differed statistically from the others; group 3 presented the lowest value and showed no differences from groups 4, 5, 7, and 8. Regarding the Adhesive Remnant Index, groups 2 and 6 presented the best results and groups 3 and 8 the worst. It could be concluded that enamel deproteinization with 10% papain gel increases the shear bond strength, irrespective of the etching agent. Conclusions: The hypothesis is rejected. Papain gel was shown to be a new ally in the orthodontic clinic. (Angle Orthod. 2012;82:541-545.)

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Objectives Three-dimensional evaluation of skeletal mandibular changes following Herbst appliance treatment. Setting and Sample Population Retrospective case–control study, based on a sample size calculation. Twenty-five pubertal patients treated with Herbst appliance (HAG), and 25 matched Class II patients who received other non-orthopaedic dental treatments (CG). Material and Methods Three-dimensional models were generated from pre-treatment (T0) and post-treatment (T1) cone beam computed tomograms. Volumetric registration on the cranial base was used to assess mandibular displacement; volumetric regional registration was performed to evaluate mandibular growth. Quantitative measurements of X, Y, Z and 3D Euclidian changes, and also qualitative visualization by colour-mapping and semi-transparent overlays were obtained. Results Downward displacement of the mandible was observed in both HAG and CG (2.4 mm and 1.5 mm, respectively). Significant forward displacement of the mandible was observed in the HAG (1.7 mm). HAG showed greater 3D superior and posterior condylar growth than the CG (3.5 mm and 2.0 mm, respectively). Greater posterior growth of the ramus was noted in the HAG than in CG. Conclusions Immediately after Herbst therapy, a significant mandibular forward displacement was achieved, due to increased bone remodelling of the condyles and rami compared to a comparison group. Three-dimensional changes in the direction and magnitude of condylar growth were observed in Herbst patients.

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The use of the Finite Element Method (FE) is an appropriate way to study occlusal forces and tooth movement. The purpose of this study was to evaluate the effects of different occlusal contact patterns on tooth displacement in an adult dentition using a three-dimensional FE model of a human maxilla and mandible. Initially, images of a computerized tomography scan were redrawn in a computer program (CATIA) followed by the FE mesh construction. The MSC/Patran software was used to develop the FE mesh comprising 520,445 elements and 106,633 nodes. The MSC/Nastran program was utilized as pre and post-processor for all mathematical calculations necessary to evaluate dental and mandibular biomechanics. Four occlusal patterns were tested: FEM 1 - standard occlusal contacts; FEM 2 - removal of mesial marginal and mesial tripoidism contacts; FEM 3 - removal of distal marginal and distal tripoidism contacts; FEM 4 - similar to FEM 3 with added contacts between upper and lower incisors. Small changes in the standard distribution of occlusal contacts resulted in an imbalance of occlusal forces and changes in dental positioning. All simulations tested showed mesial displacement of posterior teeth. The most significant changes were registered in the model presenting unstable occlusal contacts when the anterior teeth were in occlusion (FEM 4). These findings may explain mandibular incisors crowding and maxillary incisors flaring as a result of small variations in dental contacts.