Step 1: Molar with deep decay, possibly Painful or very sensitive.

Step 2: Decay is deep enough to
reach pulp, and tooth is determined to have infected or necrotic pulp.

Step 3: A conservative access to infected pulp is made through crown of tooth.

Step 4: Pulp tissue and infected tooth structure are removed,
      and canal is disinfected.

Step 5: Canals are obterated (filled) completely with gutta percha to prevent future infection.

Step 6: A restoration is placed to close and seal off access.