Figure 1
Three categories of reasons for pain or discomfort. Category 1 indicates trays with some materials missing (arrow in (A)) or non-smooth edges (arrow in (B)). Category 2 indicates deformation of the attachments at the occlusal margin (arrows in (C)) and at the gingival margin (arrow in (D)). Category 3 indicates deformation of the tray in vertical dimension (E) and in transverse dimension (F).
