Figure 2.

Relative position of the 3rd primary ruga in relation to the contact points of the first premolar and the second premolar. (a) Only the 3rd primary ruga; (b) the presence of additional posterior rugae. In total, 48% of the anterior limits of the 3rd palatal rugae without additional posterior rugae were located anterior to the first premolar and second premolar contact points. However, 84% of the anterior limits of the 3rd palatal rugae with additional posterior rugae were located anterior to the contact points of the first premolar and the second premolar.