A gummy smile is seen when having more than 3-4MM of gingival display (amount of gum tissue visible above the top teeth) ideal is between 0-2MM.

Causes:

1. Overgrown Maxilla
2. Short upper lip length
3. Hyperactive lip muscles

4.Altered passive eruption

1.Overgrown Maxilla:

The upper jaw has excessive growth, the downward growth increases the vertical height of the mid-face, exposing more of the gums.

2.Short upper lip length:

Having a small upper lip will expose your gums more, giving that gummy smile.

Men: average = 20-22MM

Short = <18

Female: average = 22-24MM

Short = <20

3.Hyperactive lip muscles:

(Strong lip muscles)

This happens when the muscles that lift the upper lip contract more than normal when smiling, lifting the upper lip exposing the gums.

4.altered passive eruption:

This is a very good short demonstration

https://youtu.be/CIW_zZzKd94?si=780dX_PXyAutPkhs