The number of petals remaining indicates which types of treatment are still possible :
one petal corresponds to simple cases (S), that is, straight, slightly curved or wide canals.
two petals correspond to moderately complex cases (M), i.e., more curved or narrow canals.
four petals correspond to difficult cases (D), i.e. canals taht are, S-shaped, very narrow, calcified or with extreme curvature.