Rachel Sattler, age 20, presents for her routine dental cleaning and checkup. She reports a constant dull ache in her top right second bicuspid that is exacerbated by temperature changes. X-rays reveal a large lesion on the distal of tooth #13 that extends toward the pulp. The likely diagnosis is extensive decay causing nerve involvement and pulpal exposure. The recommended treatment is a root canal, followed by a post/core buildup and porcelain crown to prevent fracture.