The phrase "upper incisors" refers to the set of teeth located in the upper part of our mouth towards the front. They are the sharp, thin teeth that we use for biting and cutting food. Full definition
For example, they have a dental pad in place of upper incisors to grab grass. (mindbodygreen.com)
Bite - Scissors bite with upper incisors fitting closely over the lower. (akc.org)
My son has the lip callus, receding chin, flat philtrum, his tongue bowls when he screams / cries, his outer upper incisors have worn away and he has had so many issues with eating solids (to the point of becoming anemic), he has been constantly congested with ear - infections since he was about 6 months. (mommypotamus.com)