Cervical vertebrae maturation index estimates on cone beam CT: 3D reconstructions vs sagittal sections.

OBJECTIVES: The aim of this study was to evaluate the performance of CBCT three-dimensional (3D) reconstructions and sagittal sections for estimates of cervical vertebrae maturation index (CVMI). METHODS: The sample consisted of 72 CBCT examinations from patients aged 8-16 years (45 females and 27 males) selected from the archives of two private clinics. Two calibrated observers (kappa scores: ≥0.901) interpreted the CBCT settings twice. Intra- and interobserver agreement for both imaging exhibition modes was analyzed by kappa statistics, which was also used to analyze the agreement between 3D reconstructions and sagittal sections. Correlations between cervical vertebrae maturation estimates and chronological age, as well as between the assessments by 3D reconstructions and sagittal sections, were analyzed using gamma Goodman-Kruskal coefficients (α = 0.05). RESULTS: The kappa scores evidenced almost perfect agreement between the first and second assessments of the cervical vertebrae by 3D reconstructions (0.933-0.983) and sagittal sections (0.983-1.000). Similarly, the agreement between 3D reconstructions and sagittal sections was almost perfect (kappa index: 0.983). In most divergent cases, the difference between 3D reconstructions and sagittal sections was one stage of CVMI. Strongly positive correlations (>0.8, p < 0.001) were found not only between chronological age and CVMI but also between the estimates by 3D reconstructions and sagittal sections (p < 0.001). CONCLUSIONS: Although CBCT imaging must not be used exclusively for this purpose, it may be suitable for skeletal maturity assessments.

Análise da alteração de cor em sistemas adesivos ortodônticos / Analysis of the color change in orthodontic adhesive systems

A análise da alteração de cor em sistemas adesivos ortodônticos é importante para o entendimento de seu comportamento óptico frente a situações clínicas, como a ingestão de substâncias corantes. Este trabalho estudou a pigmentação de sistemas adesivos ortodônticos, de diversas marcas comerciais, em determinados intervalos de tempo, quando expostos a fatores extrínsecos. Foram confeccionados corpos de prova – com 1 mm de espessura por 12 mm de largura – dos adesivos das marcas Aqualite (Orthosource), Natural Orto (DFL), Orthobond (Morelli), Transbond Color Change e Transbond XT, fabricados pela 3M (n=4). Os corpos de prova foram polidos por meio de uma série de lixas abrasivas e imersos no café, como substância corante, e água bidestilada, como substância controle. As curvas espectrais de reflectância foram obtidas em contato óptico, sobre fundo branco, através de um espectrofotômetro com esfera de integração acoplada. Os resultados mostraram que os fatores tempo, marca comercial e meios pigmentadores exerceram influência para o manchamento dos corpos de prova. Quanto ao fator tempo, houve alteração para todas as marcas comerciais em todos os períodos analisados.

The color change analysis of orthodontic adhesive systems is important to understand its optical behavior in clinical situations such as the ingestion of staining solutions. This study tested the pigmentation of orthodontic adhesive systems, from various commercial brands, in a period of time, after exposition to extrinsic factors. The discs with 12 mm in diameter and thickness of 1 mm were prepared with five orthodontic adhesives: Aqualite (Orthosource), Natural Orto (DFL), Orthobond (Morelli), and Transbond Color Change and Transbond XT manufactured by 3M (n=4). The samples were polished with a series of polishing discs and immersed in coffee, as staining solution, and bidestilled water, as control solution. The spectral reflectance curves were acquired on optical contact, against white background, with a integration sphere attached spectrometer. The results showed that the period of time, commercial brands and staining solutions has an influence on the disks discoloration. Regarding the time factor, all the commercial brands showed perceptible color change in all periods analyzed.

A influência do atrito na mecânica ortodôntica / The influence of friction in orthodontics

São inúmeros os fatores a serem considerados pelo profissional quando do planejamento mecânico de uma terapia ortodôntica. Dentre esses, o coeficiente de atrito tem chamado grande atenção de clínicos e pesquisadores, principalmente após a popularização dos braquetes autoligados. No presente artigo são listadas as diversas características do aparelho ortodôntico que interferem na geração de forças de atrito, ou fricção, entre o fio ortodôntico e o braquete, quando da realização de uma mecânica de deslize. Objetiva-se fornecer ao ortodontista subsídios para um melhor controle biomecânico e, desta forma, agilizar a movimentação dentária, reduzir o dano tecidual decorrente da terapia, assim como encurtar o tempo total de tratamento.