The dental midline is the line between your two upper front teeth and your two lower front teeth, and it plays a significant role in orthodontic treatment.
The dental midlines of your upper and lower jaws should align with each other in the center of your upper and lower arches. Those midlines also should align with the center of your nose and the midpoint between your eyes.
Baby teeth that fall out prematurely cannot maintain the space needed for the adult replacements. Congenitally missing adult teeth also leave room for neighboring teeth to shift into the vacant space.