There are two main features in the vertical characteristics of the smile. The first one refers to incisor display (the patient displays the entire tooth or not) and the other one refers to gingival display (the patient displays the gingiva or not).
The incisors might be shown insufficiently because of different reasons. It might be a combination of limited movement of the lip, vertical maxillary deficit, and clinically short crown height. If the main cause of inadequate tooth display is the clinically short clinical height, the orthodontist must determine if this is brought about by gum intrusion, tooth attrition or erosion or lack of tooth eruption. If the cause is gum intrusion, the treatment will be crown lengthening. If the cause is tooth attrition or erosion, the management for this will be laminates or composite buildups. Lastly, if the cause id the lack of tooth eruption, it will just settle by itself as the child gets older.
The other feature of the vertical characteristics of the smile is the gingival display. Ideally, the gingival margin of the canines should be coincident with the upper lip and the lateral incisors should be slightly below the neighbouring teeth. However, equal gingival height in smiling is still acceptable.