ABSTRACT Frictionless (segmented-arch) mechanics represent one of the most precise biomechanical approaches in orthodontics, enabling clinicians to design statically determinate force systems with predictable moment-to-force ratios. Unlike sliding mechanics, which are limited by variable resistance to sliding, frictionless systems employ loops, springs, and cantilevers to generate controlled tooth movements such as tipping, translation, and torque. Since Burstone’s introduction of the segmented-arch technique in the 1960s, advancements in β-titanium alloys and refined loop geometries have significantly improved mechanical efficiency and biological compatibility. Classic designs such as T-loops, tear-drop, and helical loops have evolved into modern variations, including Opus, snail, and K-SIR loops, validated through finite element modeling and clinical trials. These systems achieve efficient space closure, anchorage control, and vertical correction with reduced tissue trauma and root resorption. The integration of computer-aided design/computer-aided manufacturing customization, skeletal anchorage, and digital planning has further expanded the relevance of frictionless mechanics in contemporary orthodontics.
Biswas et al. (Tue,) studied this question.