Avaliação da influência de diferentes configurações de bases de bráquetes na força de remoção e remanescente de resina / Evaluation of the influence of different bracket bases designs on debonding force and resin remnant

Resumo A produção contemporânea de bráquetes ortodônticos inclui tecnologia de injeção, com diferentes desenhos de base de colagem que interferem, diretamente, na força de adesão ao esmalte e na facilidade de remoção posterior. O objetivo foi avaliar a resistência ao cisalhamento de bráquetes metálicos de três diferentes bases de colagem, verificando a força necessária para descolagem e o remanescente de resina na base do bráquete. Foram utilizados 30 dentes bovinos, colados com bráquetes U-Clip (Orthometric, Marília, SP, Brasil); ID-ALL (ID-Logical, São José do Rio Preto, SP, Brasil) e Mini Twin, (3M ESPE, St Paul, Minnesota, EUA). Todos os bráquetes foram colados com a resina Transbond XT®, (3M ESPE, St Paul, Minnesota, EUA). Após a colagem, os corpos de prova foram submetidos ao teste de cisalhamento, com registro das forças de descolagem e, posteriormente, foram avaliados o adesivo remanescente e o padrão de falha em um estereomicroscópio óptico. As forças de cisalhamento foram semelhantes entre os grupos U-Clip e ID-ALL, que foram estatisticamente diferentes do grupo Mini-Twin. Os bráquetes U-Clip e Mini-Twin apresentaram todo o remanescente de resina aderido à base do bráquete, enquanto o bráquete ID-ALL apresentou mais da metade do remanescente aderido à base do bráquete, resultado estatisticamente significante. Conclui-se os bráquete nacionais apresentam menor força de cisalhamento, estatisticamente significante quando comparados ao bráquete Mini-Twin. O bráquete ID-ALL apresentou o menor remanescente de resina, denotando que a fratura ocorreu na camada de resina, enquanto que nos grupos U-Clip e Mini-Twin, a fratura ocorreu na interface resina/esmalte. (AU)

Abstract The contemporary production of orthodontic brackets includes injection technology, with different designs of bonding bases that interfere directly with the bond strength to enamel and the ease of subsequent removal. The aim was to evaluate the shear bond strength of metal brackets of three different bonding bases, checking the force required for debonding and the rates of resin remaining on the bracket base. The sample consisted of 30 bovine teeth bonded with brackets U-Clip (Orthometric, Marília, SP, Brazil), ID-ALL (ID-Logical, São José do Rio Preto, SP, Brazil), and Mini Twin (3M ESPE, St Paul, Minnesota, USA). All brackets were bonded with Transbond XT resin (3M ESPE, St Paul, Minnesota, USA). After bonding, the specimens were subjected to a shear bond test. The forces required for debonding were recorded. Posteriorly, the remaining adhesive and failure patterns were evaluated in an optical stereomicroscope. The shear forces were similar for U-Clip and ID-ALL, which were significantly different from the Mini-Twin group. The U-Clip and Mini-Twin brackets showed the resin remnant totally adhered to the bracket base, while the ID-ALL bracket had more than half of the resin remnant attached to the bracket base, a statistically significant result. It was concluded that shear forces were lower for the national brackets, statistically significant. Bracket ID-ALL had the least resin remnant in the base, denoting that the fracture occurred in the resin layer. In contrast, in the U-Clip and Mini-Twin brackets groups, the fracture occurred at the resin/enamel interface (AU)

Cytokine profiles of healthy and diseased sites in individuals with periodontitis.

OBJECTIVE: The aims of this study were: 1) to compare the levels of cytokines between healthy and diseased sites, in patients with untreated periodontitis; 2) to correlate cytokine levels with each other and with key periodontal pathogens, in healthy and diseased sites. METHODS: Paired gingival crevicular fluid (GCF) samples were obtained from two healthy (probing depth (PD) and clinical attachment level (CAL) ≤3 mm without bleeding) and two diseased sites (PD and CAL ≥5 mm with bleeding on probing [BoP]) of patients with generalized stage III/IV grade B/C periodontitis. GCF levels of eighteen cytokines and subgingival levels of seven periodontal pathogens were assessed by multiplex immunoassay and qPCR, respectively. RESULTS: A total of 112 subjects and 448 GCF samples were analyzed. The GCF levels of GM-CSF, IL-17, IL-1ß, IL-2, IL-21, IL-23 and TGF-ß were significantly higher in the diseased than in the healthy sites (p < 0.05). Levels of IL-8 and MIP-1α were significantly higher in the healthy than in the diseased sites (p < 0.05). In the healthy sites, IL-8 and MIP-1α formed an independent cluster of cytokines and, MIP-1α positively correlated with Porphyromonas gingivalis (p < 0.05). In deep sites, smoking negatively associated with GM-CSF, IL-10, IL-17, IL-23, IL-5, IL-6, IL-7, IL-8 and MIP-1α levels (p < 0.05). CONCLUSIONS: Diseased sites exhibited increased levels of T helper 17-related cytokines and TGF-ß while healthy sites presented increased levels of the chemokines, IL-8 and MIP-1α. Patients with periodontitis may not only have inflammation in diseased deep sites, but also present significant hidden subclinical inflammation in their shallow clinically healthy sites.