Acompanhamento de restaurações em diastemas anteriores com resina composta pela técnica de barreira palatina: relato de caso / Follow-up of anterior teeth diastema restoration with composites using palatine barrier technique: case report

A presença de diastemas ântero-superiores pode influenciar negativamente os aspectos estético e psicológico do indivíduo. O objetivo deste estudo é apresentar um relato de caso clínico em que foi realizado o fechamento de diastemas ântero- -superiores com restaurações em resina composta, utilizando a técnica da barreira palatina e seu acompanhamento por dois anos. Diante do planejamento e terapia executados no caso clínico apresentado, pode-se concluir que a técnica restauradora utilizando resinas compostas e barreira palatina, quando corretamente indicada, pode ser considerada uma alternativa de tratamento bastante satisfatória no fechamento de diastemas e na reanatomização de dentes por ser uma técnica simples, de baixo custo e por melhorar a estética do sorriso preservando a estrutura dental hígida. O repolimento anual está indicado para a preservação da cor das restaurações.

Anterior diastema may influence negatively the esthetics and psychological aspects of an individual. This study goal is to present a clinical report in which there was restorations of multiple anterior diastema with composites, using the palatine barrier technique and its two year follow-up. Considering the therapy that was planned and executed on this report, we may conclude that the restorative technique using composites and palatine barrier, when correctly indicated, can be considered a satisfactory treatment alternative for diastema restoration due to its simple execution, low cost and smile esthetics improvement preserving tooth structure. Annual repolishing is indicated for color preservation of the restorations.

Stress distribution in a premolar 3D model with anisotropic and isotropic enamel.

The aim of this study was to compare the areas of stress concentration in a three-dimensional (3D) premolar tooth model with anisotropic or isotropic enamel using the finite element method. A computed tomography was imported to an image processing program to create the tooth model which was exported to a 3D modeling program. The mechanical properties and loading conditions were prescribed in Abaqus. In order to evaluate stresses, axial and oblique loads were applied simulating realistic conditions. Compression stress was observed on the side of load application, and tensile stress was observed on the opposite side. Tensile stress was concentrated mainly in the cervical region and in the alveolar insertion bone. Although stress concentration analyses of the isotropic 3D models produced similar stress distribution results when compared to the anisotropic models, tensile stress values shown by anisotropic models were smaller than the isotropic models. Oblique loads resulted in higher values of tensile stresses, which concentrate mainly in the cervical area of the tooth and in the alveolar bone insertion. Anisotropic properties must be utilized in enamel stress evaluation in non-carious cervical lesions.

3D finite element analysis on esthetic indirect dental restorations under thermal and mechanical loading.

Thermo-mechanical finite element analyses in 3-D models are described for determination of the stress levels due to thermal and mechanical loads in a healthy and restored tooth. Transient thermo-mechanical analysis simulating the ingestion of cold and hot drinks was performed to determine the temperature distribution in the models of the teeth, followed by linear elastic stress analyses. The thermal loads were applied on the occlusal and lingual surfaces. Subsequently, coupled variation of the temperature and mastication loading was considered. The vertical loading was distributed at occlusal points, adding up to 180 N. Maximum stresses were verified in resin restoration under thermal loads. When studying coupled effect of mechanical loading with that arising from thermal effects, higher tensile stress values occurred in porcelain restorations, especially at the restoration-dentin interface. Regions of high tensile stress were detected and their possible clinical significance with respect to restoration damage and microleakage were discussed.

Abfraction and anisotropy--effects of prism orientation on stress distribution.

This work discusses the effect of enamel anisotropy in the stress concentration at the cement-enamel junction (CEJ), a probable cause of fracture in enamel leading to abfraction. Usual simplifications when developing computer models in dentistry are to consider enamel isotropic, or that the direction of the prisms is orthogonal to either the dentine-enamel interface or the tooth outer surface. In this paper, a more refined model for the material behavior is described, based on laboratory observation and on the work of Fernandes and Chevitarese. The material description is used in a two-dimensional (2D) finite element model of the first upper premolar, and the analysis is performed for two different situations: vertical loads, typical of normal mastication and horizontal loads, dominant in bruxism. The analyses were performed using a unit load, which under the hypothesis of linear response of the tooth, allows the combinations described in the text to simulate different functional and parafunctional loads. The results indicate that a realistic enamel description in terms of mechanical properties and spatial distribution of its prisms alters significantly the resulting stress distribution. For all cases included in this study, the detailed description of prism orientation and resulting anisotropy led to improved response in terms of stress distribution, even when loading was horizontal.