Testing the tensile fracture strength tie-wings of different orthodontic ceramic bracket using an Instron machine

Newly released products should address the shortcomings of the older ones. Frequent breakages have always been a major drawback when using ceramic brackets. This study assessed the difference in tensile fracture strength at maximum load of tie-wings of different orthodontic ceramic brackets recently available for clinical use.

In this in-vitro study, four ceramic brackets were examined. Two monocrystalline brackets (CLEAR™, Adanta®, Germany; Inspire ICE™, Ormco®, USA), one polycrystalline bracket (Symtri Clear™, Ormco®, USA), and one clear hybrid bracket (DISCREET™, Adanta®, Germany). A steel ligature wire was placed around the tie-wing and on the Instron machine to apply tension. The mean maximum load (MxL) and fracture strength (FS) was evaluated and recorded. The significance level was set at p ≤ 0.05.

Statistical difference in fracture strength of the tie-wing fracture was noted among all four groups. Inspire ICE™ showed the highest maximum load and fracture strength with (202.78 N and 107.3 MPa), followed by Symtri Clear™ (111.99 N and 59.25 MPa). In contrast, CLEAR™ and DISCREET™ showed lower MxL values (79.63 N and 47.01 N). The monocrystalline Inspire ICE™ brackets showed the greatest tie-wing fracture resistance and the hybrid clear ceramic bracket DISCREET™ exposed the least resistance to fracture.

Brand (manufacturing specifications) as well the bracket crystalline structure seems to have a direct effect on its tie-wing strength.