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Objective: To evaluate, in vitro, the shear bond strength of self-curing (Concise TM -3M and Alpha Plast -DFL) and light-curing composites (Transbond TM XT -3M and Natural Ortho -DFL) used in orthodontics bonding, associated to Morelli metal brackets, with further analysis of adhesive remnant index (ARI) and enamel condition in scanning electron microscopy (SEM). Methods: Forty human premolars, just extracted and stored in physiologic solution 0.9 % were used. Randomly, these samples were divided in four groups: G1 group, the brackets were bonded with Concise TM -3M composite; in G2 group, Alpha Plast -DFL composite was used; in G3 group, Transbond TM XT -3M was used; in G4 group, Natural Ortho -DFL composite was used. These groups were submitted to shear strength tests in universal testing machine, at 0.5 mm per minute speed. Results: Statistical difference between G3 and G4 groups was recorded, as G4 showing higher strength resistance than G3. In the other hand, there were no statistical differences between G1, G2 and G3 and G1, G2 and G4 groups. ARI analysis showed that there was no statistical difference between the groups, and low scores were recorded among then. The scanning electron microscopy (SEM) analysis revealed the debonding spots and the enamel surface integrity. Conclusions: Shear bond strength was satisfactory and similar between the composites, however Natural Ortho -DFL revealed best comparing to Transbond TM XT -3M. Keywords: Composite resins. Shear strength. Scanning electron microscopy.How to cite this article: Neves MG, Brandão GAM, Almeida HA, Brandão AMM, Azevedo DR. In vitro analysis of shear bond strength and adhesive remnant index comparing light-curing and self-curing composites. Dental Press J Orthod. 2013 May-June;18(3):124-9.» The authors report no commercial, proprietary or financial interest in the products or companies described in this article. Objetivo: avaliar in vitro a resistência ao cisalhamento de compósitos autopolimerizáveis (Concise e Alpha Plast) e fotopolimerizáveis (Transbond XT e Natural Ortho) utilizados na colagem de braquetes metálicos da marca Morelli, analisando o índice de adesivo remanescente (ARI) e da integridade da superfície do esmalte por meio de microscopia eletrônica de varredura (MEV). Métodos: foram utilizados 40 pré-molares humanos extraídos. As raízes dos dentes foram incluídas em gesso-pedra especial, no interior de tubos de PVC usados para a confecção dos corpos de prova. Esses corpos de prova foram divididos em quatro grupos: grupo G1, braquetes associados ao compósito Concise; grupo G2, braquetes associados ao compósito Alpha Plast; grupo G3, braquetes associados ao compósito Transbond XT; e grupo G4, braquetes associados ao compósito Natural Ortho. Os grupos foram submetidos ao teste de cisalhamento em máqui-na universal de ensaios, a uma velocidade de 0,5mm por minuto. Resultados: houve diferença estatística entre os grupos G3 e G4, sendo os valores de G4 superiores; no entanto, não foram encontradas diferenças estatisticamente significativa...

Introduction: The aim of this in vitro study was to compare the elastic properties of the load-deflection ratio of orthodontic wires of different lot numbers and the same commercial brand. Methods: A total of 40 nickel-titanium (NiTi) wire segments (Morelli OrtodontiaTM - Sorocaba, SP, Brazil), 0.016-in in diameter were used. Groups were sorted according to lot numbers (lots 1, 2, 3 and 4). 28-mm length segments from the straight portion (ends) of archwires were used. Deflection tests were performed in an EMIC universal testing machine with 5-N load cell at 1 mm/minute speed. Force at deactivation was recorded at 0.5, 1, 2 and 3 mm deflection. Analysis of variance (ANOVA) was used to compare differences between group means. Results: When comparing the force of groups at the same deflection (3, 2 and 1 mm), during deactivation, no statistical differences were found. Conclusion: There are no changes in the elastic properties of different lots of the same commercial brand; thus, the use of different lots of the orthodontic wires used in this research does not compromise the final outcomes of the load-deflection ratio.

The friction is a factor that can result on changes in efficacy of sliding orthodontic mechanics. Different factors can impact on the friction force: the composition and properties of orthodontic wires and brackets, the cleaning of orthodontic braces, and even saliva. This study aimed to evaluate the friction in two brands before and after use in the oral environment. Ten patients from the orthopedic clinic of the Master’s of Dentistry, with two premolars bonded of each patient. The patients were divided, according with total number of brackets (n= 40): 2 control groups - without exposure to the buccal medium - (G1 and G2) and 2 experimental groups - with exposure to the buccal medium - (G3 and G4). The brackets were testes on a friction machine and evaluated in a two-way ANOVA test. It was observed that the brand used in groups G2 and G4 presented greater friction with the orthodontic wire and the G2 group brackets presented similar frictional force to G3, which had already been exposed to clinical use. Brazilian brackets brands presented an increased friction after clinical use.