The canal configuration of this tooth can be quite complex. Vertucci Fig. 9 A lower second premolar with a severe distal curve at the apex. has shown that the single canal normally found may divide into two canals and two apical foramina in 25% of cases. It is the way in which the second canal branches that can cause difficulty with instrumentation. Occasionally, the canal terminates with an extensive delta, making obturation of the accessory canals even more challenging. As in the upper premolars, the access cavity is oval between the cusp tips.