Angle Pearls Compound Adjustment Editor's Note: Starting with this issue, we are introducing a new column called "Angle Pearls." We have three components of the Edward H. Angle Society of Orthodontists in the PCSO. Any Angle members from the PCSO can submit their pearls. Dr. Gerald Nelson will be the editor of this column and can be reached at gerald.nelson@ucsf.edu. Intrusion / Extrusion effects Force is displaced from the center of resistance Figure 1: When you make a vertical adjustment on a single tooth, you may not get the bodily movement you want. Figure 2: Since the center of resistance is not in line with the force vector, a moment is produced that will flare the crown to the buccal. The result is intrusion + buccal crown movement Compound adjustment helps Dr. Gerald Nelson UCSF Orthodontic Division Figure 4: The amount of slot play between the wire and the slot is what allows the moment to tip the tooth. A solution is to adjust the wire both vertically and to the lingual. Figure 3 Force vector is moved toward the center of resistence Figure 5: Bodily intrusion is facilitated. 68 Milder moment, better change in crown position Figure 6 PCSO Bulletin Winter 2017