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The objective of this study was to evaluate the influence of bracket base mesh geometry on the stresses generated in the bracket-cement-tooth continuum by a shear/peel load case. A validated three- dimensional finite element model of the bracket-cement-tooth system was constructed consisting of 15,324 nodes and 2971 finite elements. Cement geometric and physical properties were held constant and bracket base geometry was varied, representing a variety of single-mesh configurations and 1 double-mesh design. For the single-mesh designs, increasing wire diameter (100-400 μm) resulted in a decrease in enamel and cement stresses. Increases in wire mesh spacing (200-750 μm) increased the major principal stress recorded in the enamel and adhesive at all wire diameters. Within the bracket, the major principal stress increased significantly at wire spacing above 400-500 μm. However, within the impregnated wire mesh (IWM), the major principal stress decreased as wire space increased. When the double-mesh bracket base was considered, the combined mesh layers resulted in a decrease in the stresses recorded in the most superficial (coarse) mesh layer and an increase in the stresses recorded in the deepest (fine mesh) layer when compared with the single-layer designs in isolation. Modification of single-mesh spacing and wire diameter influences the magnitude and distribution of stresses within the bracket-cement-tooth continuum. The use of a double- mesh design results in a reduction in the stresses recorded in the most superficial mesh. Mesh design influenced stress distribution in this study, primarily by determining the flexibility of the bracket base. [ABSTRACT FROM AUTHOR]

The objectives of the study were to isolate the bracket-cement interface, and to determine the influence of bracket base morphology and orthodontic bonding agent chosen on strength of adhesion. The bracket bases evaluated included 60, 80, and 100 single mesh bases, a double mesh base, and the Dynalock™, and Mini Twin™ bases. The strength of interface provided by each of these bases with Concise™, Transbond™, Right On™, and non-encapsulated Fuji Ortho LC™ cements, was measured in tension and recorded in Mega Pascals. The single-mesh bases performed well with either Concise or Right On (11∙88-22∙72 MPa) and, other than the 80-mesh bracket, relatively poorly with Transbond (2∙18-5∙15 MPa). With Fuji Ortho LC, the single mesh bases performed well (6∙05-12∙19 MPa). The double mesh base performed well with Right On (13∙75 MPa), and reasonably well with Concise, Transbond, and Fuji Ortho LC (6∙00-9∙20 MPa). The Dynalock and Mini Twin Bases performed fairly well with all cements (8∙87-17∙16 MPa). It was concluded that the orthodontic bonding agent selected would appear to largely determine the bond strength achieved with a particular bracket base design. A definite trend was difficult to identify in this study, and it appeared that certain combinations of bracket base and bonding agent performed optimally. Particular base designs may allow improved adhesive penetration or improved penetration of curing light. Alternatively, the dimension and distribution of resin/cement tags prescribed by one base could promote a stress distribution that is better resisted by a particular adhesive. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the resilience, glass transition temperature (Tg), ultimate flexural strength (UFS), and penetration coefficient of 3 composite adhesives (Concise, Transbond, and Right On) and a glass ionomer cement (Fuji Ortho LC). For 25 minutes after initial set, the composite materials were significantly more resilient than Fuji Ortho LC (P = .000). Resilience values for all materials increased for up to 90 minutes after initial set, reflecting a continuation of their setting reaction. Right On remained the most resilient material at 90 minutes after initial set (P = .01). At 120 minutes, there was no significant difference in the resilience of Concise, Right On, and Fuji Ortho LC. However, Transbond was significantly less resilient than these materials (P = .01). The composite materials recorded significantly higher glass transition values (89-123°C) than Fuji Ortho LC (54°C). The composite materials were also significantly stronger (61-68 MPa) than Fuji Ortho LC (35 MPa) in flexion. The penetration coefficients of Concise and Transbond were significantly higher (P = .001) than Right On and Fuji Ortho LC. However, the relative penetration coefficients of the materials studied did not appear to influence the degree of bracket base penetration achieved by the cements. In conclusion, Fuji Ortho LC offered a reduced energy-absorbing capacity immediately after bracket placement and reduced cohesive and mechanical adhesive strength. In addition, the glass transition temperature of Fuji Ortho LC was low; this may result in compromised attachment at temperatures above 60°C. Significant differences in the penetration coefficient of the materials studied have been recorded. However, the penetration of the 4 cements into a range of bracket base morphologies was uniformly good. Therefore, the differences in penetration coefficient recorded should not influence the quality of the bracket cement interface provided. [ABSTRACT FROM AUTHOR]

The objective of the investigation was to develop a clinically valid three-dimensional computer model of the orthodontic bracket-cement-tooth continuum, and determine the magnitude and distribution of stresses generated by three different load cases. A three-dimensional finite element model of the bracket-cement-tooth system was constructed consisting of 15324 nodes and 2971 finite elements. The stresses induced in the bracket-tooth interface by a masticatory load, a peel force and a twisting couple were recorded. The maximum principal stresses resulting from occlusal and 'twisting' forces are distributed toward the lute periphery. Peel forces, applied to the bracket tie wing, are concentrated beneath the bracket stem. Twisting forces result in the highest enamel stresses. The quality of orthodontic attachment can be explained by the magnitude and distribution of major principal stresses within the cement and impregnated bracket base. Shear and shear/peel forces are most likely to induce crack propagation within the adhesive layer. However, when a twisting action is used to remove orthodontic brackets, enamel failure is most likely. A clearer insight into the complexity of the bracket-cement-tooth system has been provided by numerical and finite element investigations. Further investigations, evaluating the influence of bracket base designs and orthodontic cement physical and geometric properties are indicated. [ABSTRACT FROM AUTHOR]

Information about several topics discusses at the First International Orthodontic Editors' Symposium sponsored by the World Federation of Orthodontists (WFO) is presented. It mentions that the symposium was made possible to explore the ways to elevate the orthodontic journalism standards. The editors discussed the article preparation and submission standardization, the potential of online journalism, and the impact factor scores of orthodontic journals and information dissemination.

The article discusses various reports published within the issue, including one on changing the name of the journal from "British Journal of Orthodontics" to "Journal of Orthodontics," one on the international profile of the journal and one on journal layout which follow an established format.