Straight and angulated abutments in platform switching: influence of loading on bone stress by three-dimensional finite element analysis

PURPOSE: In view of reports in the literature on the benefits achieved with the use of platform switching, described as the use of an implant with a larger diameter than the abutment diameter, the goal being to prevent the (previously) normal bone loss down to the first thread that occurs around most implants, thus enhancing soft tissue aesthetics and stability and the need for implant inclination due to bone anatomy in some cases, the aim of this study was to evaluate bone stress distribution on peri-implant bone, by using three-dimensional finite element analysis to simulate the influence of implants with different abutment angulations (0 and 15 degrees) in platform switching. METHODS: Four mathematical models of an implant-supported central incisor were created with varying abutment angulations: straight abutment (S1 and S2) and angulated abutment at 15 degrees (A1 and A2), submitted to 2 loading conditions (100 N): S1 and A1-oblique loading (45 degrees) and S2 and A2-axial loading, parallel to the long axis of the implant. Maximum (σmax) and minimum (σmin) principal stress values were obtained for cortical and trabecular bone. RESULTS: Models S1 and A1 showed higher σmax in cortical and trabecular bone when compared with S2 and A2. The highest σmax values (in MPa) in the cortical bone were found in S1 (28.5), followed by A1 (25.7), S2 (11.6), and A2 (5.15). For the trabecular bone, the highest σmax values were found in S1 (7.53), followed by A1 (2.87), S2 (2.85), and A2 (1.47). CONCLUSIONS: Implants with straight abutments generated the highest stress values in bone. In addition, this effect was potentiated when the load was applied obliquely.

The influence of the alveolar ridge shape on the stress distribution in a free-end saddle removable partial denture supported by implant

The alveolar ridge shape plays an important role in predicting the demand on the support tooth and alveolar bone in the removable partial denture (RPD) treatment. However, these data are unclear when the RPD is associated with implants. This study evaluated the influence of the alveolar ridge shape on the stress distribution of a free-end saddle RPD partially supported by implant using 2-dimensioanl finite element analysis (FEA). Four mathematical models (M) of a mandibular hemiarch simulating various alveolar ridge shapes (1-distal desceding, 2- concave, 3-horizontal and 4-distal ascending) were built. Tooth 33 was placed as the abutment. Two RPDs, one supported by tooth and fibromucosa (MB) and other one supported by tooth and implant (MC) were simulated. MA was the control (no RPD). The load (50N) were applied simultaneously on each cusp. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys 10.0 software was used to calculate the stress fields and the von Mises equivalent stress criteria (σvM) was applied to analyze the results. The distal ascending shape showed the highest σvM for cortical and medullar bone. The alveolar ridge shape had little effect on changing the σvM based on the same prosthesis, mainly around the abutment tooth.

La relacion entre la calidad de la ensenanza y mala prática odontológica: relato de un caso clínico

The activities developed in health area are of great importance, because they have the aim to preserve the life of the men, and therefore, must be performed by authorized persons. The increase of the number of dental schools, the decline at the education quality and a higher admission of students with low ability to exercise their profession, are facts that bring disastrous consequences for society. These facts are, also, reflected at the moral, ethical and technical-scientific performance of the professional. The purpose of this clinic case is to show that although there is a significant suplly of education institutions, there is a lack of scientific and adequate technical knowledgement from the graduated dentals surgeons. The patient MSL, 17 year old, female, went to a dental clinic presenting a tray type Vernis, attached to the lower arch. After clinical evaluation, it was showed that an incorrect material was used for the impression technique, being impossible to take out the tray by the conventional manner. The planning for the removal of the tray was through the divide of it. Thus, the consequence of the lack of knowledge in the use of impression materials had caused a great incovinience to the patient. It can be concluded that the rate of malpractice is directly related to the professional preparation, highlighting the importance of quality dental education for a responsible clinical practice.

A relevância do periodontista na prevenção da doença periodontal em pacientes ortodônticos: relato de caso clínico

The increase of the retentive areas of bacterial plaque can be observed in patients who use dental braces in the mouth. The difficulty of making hygienic is one of the problems that this particular group of patients faces day by day, and consequently, the establishment of gingival inflammation becomes more frequent. The objective of this case report is to show the importance of the periodontist in preventing and promoting health to the users of dental braces, aimed at education and motivation as one of the priorities of this treatment. The ESA patient, 29 years old, male, attended the dental office of a periodontist, sent by the orthodontist, due to the extensive area of gingival hyperplasia and gingivitis, in both arches. The possibility of taking out the dental braces was considered by the orthodontist, but after the periodontist evaluation, this step was procrastinated. Thus, the periodontist started the adequacy of the oral environment together with the work of education and promotion of health, which lasted until the complete recovery of the healthy gingival condition of the patient. In this way, it is possible to observe the relevance of the work of the periodontist in the application of preventive methods in oral health for orthodontic patients. The motivation of these patients in relation to the orientations of buccal hygienic, maintenance of oral health and diet should not be considered as secondary and should be prioritized, because only in this way it would be possible to reach a good occlusion, without esthetic and functional prejudice.

Pemphigus vulgaris in adolescence: a case report

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Métodos de coleta de deposição para ensaios de deriva em aplicações aéreas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estruturação de metacomunidades de girinos em diferentes fitofisionomias da Mata Atlântica: uma análise em diferentes escalas espaciais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The briefing in paleodesign: selection and arrangement of data for the reconstruction of Paleovertebrates

Representing visually the external appearance of an extinct animal requires, for a reasonably reliable and expressive reconstitution, a good compilation and arrangement of the scientific conclusions on the fossil findings. It is proposed in this work an initial model of a briefing to be applied in a paleodesign process of a paleovertebrate. Briefing can be understood as a gathering of all necessary data to perform a project. We point out what must be known about the relevant structures in order to access all the data and the importance of such information. It is expected that the present briefing suggested might be faced with flexibility, serving as a facilitating interface of the relation between paleoartists and paleontologists.

Formação de professores e seus saberes disciplinares em astronomia essencial nos anos iniciais do ensino fundamental

This paper presents some outcomes of a broader research on Astronomy Education in primary school teacher's education. From the analysis of the main astronomy subjects thought nationwide and the research outcomes, we identified a set of astronomy contents considered fundamental to the teachers practice. Through a research carried out among a sample of primary school teachers, however, we show that, even in these essential contents, persists alternative conceptions among those teachers. Data collected pointed out, thus, to the necessity of improving teacher's education in this area, taking into consideration astronomy edu cation research outcomes, in favor of a teaching which contemplates, at least, the fundamental contents on this subject.

Interpretando reflexões de futuros professores de Física sobre sua prática profissional durante a formação inicial: a busca pela construção da autonomia docente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Trajetórias Formativas Docentes: buscando aproximações na bibliografia sobre formação de professores

This paper is a theoretical review where we present teachers’ formative trajectories, according to concepts and significations from teachers' education literature, bibliography references to the UNESP Science Education Research Group. We summarize, in an overview table, different typologies associated to teachers' formative and professional development, trying to establish relationships among them. This study is aimed at to rethink these trajectories, in order to provide subsidies for future investigation in this research line.