Bracket slot and archwire dimensions: manufacturing precision and third order clearance

Objective: To determine the accuracy of different manufacturer’s dimensions of bracket slots and stainless steel archwires and compare these against the tolerance limits given by DIN 13971 and 13971‐2. Further to calculate torque play and effective torque and to compare the results to nominal torque. Design: A laboratory investigation. Setting: The Department of Orthodontics and Dentofacial Orthopedics at Medical University of Graz, Austria. Materials and methods: Ten upper central incisor brackets (0·022 inch) from five different bracket systems were investigated. Bracket slot height was measured with leaf gauges. The height and width of 10 stainless steel archwires with dimensions either 0·019×0·022 or 0·020×0·025 inch were measured using a micrometer. Results: All measured bracket slot heights were within the upper and lower tolerance limits given by DIN 13971‐2. Archwires showed measurements outside the upper and lower tolerance limits given by DIN 13971. The smallest effective torque loss (4·5°) resu...