Fig. 1From: A comparative study on anterior teeth retraction-related hard and soft tissue changes with physiologic anchorage control techniqueCrossed buccal tube (XBT). (top) with insertion of the archwire into the -25-degree auxiliary tube, anterior archwire will locate gingivally to the anterior teeth; (bottom) after anterior archwire engaging in the brackets, a tip-back moment will be generated on molar to reinforce molar anchorageBack to article page