Figure 1
From: Palatal rugae morphology is associated with variation in tooth number
Morphological classification of primary rugae. Primary rugae were classified according to SHAPE, CONTINUITY and DIRECTION. SHAPE was classified as Straight (a straight line from origin to termination), Curved (a simple gently curving crescent shape), Wavy (a serpentine shape or the presence of any curve at the origin or termination of a curved rugae) and Circular (a definite continuous ring). CONTINUITY between rugae was classified as Convergent (a split origin in the midline and converging laterally), Divergent (a single origin in the midline and diverging laterally or Distinct (with no unification and as shown in SHAPE). DIRECTION was classified as Type I–IV according to the relationship between the midline origin and lateral termination in relation to the anterior–posterior axis of the palate midline. Type I (Posterior–Anterior) have an origin situated posterior to the termination; Type II (Perpendicular) have an origin and termination in the same plane; Type III (Anterior–Posterior) have an origin situated anterior to the termination and Type IV are Multi-directional. Vertical lines represent palatal midline. (a) anterior; (p) posterior.
