Effects of bracket design on critical contact angle
Related Experiment Video
Updated: May 12, 2026

Parametric Optimization Design Method for Friction Plates of Hydro-Viscous Clutches
Published on: July 22, 2025
Xiaomo Liu1, Peng Ding, Jiuxiang Lin
1Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China.
Objective:
To explore how the position of the bracket slots relative to the archwire influences the friction between them, and how bracket design affects the critical contact angle (θc).
Materials And Methods:
Two kinds of stainless steel archwires (0.016 and 0.019 × 0.025-inch) were tested against four kinds of brackets (Transmission Straight Archwire bracket, Domestic MBT bracket, Tip-Edge Plus bracket, and BioQuick self-ligation bracket) in the dry state. Resistance to sliding (RS) was measured as an increase in contact angle (θ). The value of θc was calculated by two linear regression lines.
Results:
Friction remained stable when θ < θc, then increased linearly when θ > θc. The θc values of the Tip-Edge Plus bracket and Transmission Straight Archwire bracket were significantly larger than those for the Domestic MBT bracket and BioQuick self-ligation bracket.
Conclusions:
The relationship between the archwire and bracket slot significantly affects the resistance to sliding. The "edge-off" structure of the Tip-Edge Plus bracket and Transmission Straight Archwire bracket could help to increase the θc value, and to expand the passive configuration range.
Related Concept Videos
Contact Angle
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
Stress Concentrations in Circular Shafts
Bearings: Problem Solving
Stress Concentrations
Stress Concentrations
The stress concentration...
Design of Transmission Shafts - Stress Analysis
