Expose the whole upper arch as much as possible, simply by retracting the upper lip with the cheek retractor (Fig.8 vs. 8', mirror view).  The end of the mirror should be as far away from the object of interest (the upper teeth) as possible.

Photos for Ortho Last Next

Xin Wei, DDS, PhD, MS 1st edition 07/29/2018, last revision 07/30/2018