Comparison of Frictional Resistance in Conventional Brackets with Different Stainless Steel Wires

The aim of the study was to evaluate and compare static and kinetic friction of round (0.018") and rectangular (0.019 × 0.025") stainless steel (SS) wires of different brands with conventional preadjusted edgewise brackets.

Maxillary canine and two bicuspids of 0.022 × 0.028" slot sized MBT prescription (Gemini, 3M Unitek, Monrovia, California) brackets were chosen. The wires selected were 0.018" SS (3M Unitek); 0.018" Australian wire (AJ Wilcock, UK), and 0.019 × 0.025" SS (3M Unitek). The testing was done on Instron 3382. A total of 30 test combinations with three wires were repeated 10 times. The static and kinetic friction was recorded in Newton. The kinetic friction was also recorded in Newton at 3, 5, 7, and 9 mm of movement. One-way analysis of variance (ANOVA) and descriptive statistics were used for comparing the friction. To test the level of significance, multiple comparisons were used within wire in bracket by using post hoc test.

Static friction was found to be greater than kinetic in all wires; 0.018" SS (3M) wire exhibited minimum static and kinetic friction; while 0.019 × 0.025" SS (3M) exhibited maximum static friction. Kinetic friction was similar in both 0.018" AJ Wilcock and 0.019 × 0.025" SS but greater than 0.018" SS (3M).

Least static and kinetic friction was exhibited by 0.018" SS (3M). Kinetic friction was similar in both 0.018" AJ Wilcock and 0.019 × 0.025" SS.

The study concluded that 0.018" SS (3M) is better for individual canine retraction than the other wires used in the study because it has the least frictional resistance; 0.019 × 0.025" SS (3M) is a better wire for canine retraction than 0.018" AJ Wilcock as we can have a three-dimensional control over tooth movement. When torque control is not a prime requisite, then 0.018" SS (3M) can be used for retraction of incisors instead of 0.018" AJ Wilcock in severely proclined incisor cases.