The Sims 4 Mouthpreset N34 by PlayersWonderland
This mouthpreset adds a new morphed, smaller looking mouth.
Available for all ages and all genders. It has one style and is a non default preset.
You can find it by clicking on the mouth of your Sim in full CAS
If the Mouthpreset doesn’t show the custom thumbnail, try deleting the localthumbcache file in your Sims 4 folder.