The Influence of Bracket Base Design on the Strength of the Bracket–Cement Interface

Abstract

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.

The relationship between base dimensions, force to failure, and shear bond strengths of bondable molar tubes

“…In contrast, Tube A, with the greatest base contour, gave the lowest bond strength; this may have resulted in part from increased thickness of adhesive present between the base surface and the substrate. Although such variations in adhesive thickness due to base curvature could not Although it has been suggested that brackets that allowed better penetration of light would produce higher bond strengths, 21 this suggestion was not supported in the current study by consideration of Tube B with its polymeric base specifically designed to allow greater light transmission during curing. The tube demonstrated the second lowest median force to failure (81.80 N) and the lowest median bond strength (3.85 MPa).…”

Reconditioning of self-ligating brackets

“…Previous investigations 17,18 indicated a strong relationship between the base of orthodontic brackets and the retention capability because the morphology of the base design may improve the penetration of the adhesive material. 19 Moreover, when evaluating scanning electron microphotographs of the recessions of the bracket base (Figure 3), the Quick bracket ( Figure 3C) showed a smoother surface pattern than did the Smart Clip ( Figure 3A) and Damon3MX ( Figure 3E) brackets. After the reconditioning procedure minimal changes were observed for Smart Clip ( Figure 3B) and Damon3MX ( Figure 3F) brackets, whereas with Quick brackets a rougher surface was observed ( Figures 3D). The base of the Quick bracket differ from those of the other two tested brackets because grooves are equipped with hook-style undercuts that should improve resin adhesion on a bracket base.…”

Quantitative analysis of mechanically retentive ceramic bracket base surfaces with a three-dimensional imaging system

“…Also, adhesion at the bracket cement interface is achieved by the provision of mechanical undercuts into which the orthodontic adhesive extends before polymerization. 8 In contrast, three kinds of mechanically retentive ceramic brackets used in this study have base surface textures (irregular texture, single mesh, and small beads) that are different from that of the metal bracket. As a result, the surface roughness value, whole and unit bracket base surface area, and surface increment ratio of ceramic brackets are lower than those of the metal bracket.…”

“…Bracket base morphology can influence the bond strength of brackets by determining the geometry (depth, size, and distribution) of the cement tags and stress distribution within the cement bracket interface. 8 However, few studies have examined the bracket base itself. Most studies examined metal brackets and only used two-dimensional analysis.…”