Complex sentence: Once the decay passes through enamel, the dentinal tubules, which have passages to the nerve of the tooth, become exposed, resulting in pain that is transient, temporarily worsening with exposure to heat, cold, or sweet foods and drinks.
Split into simpler sentences: Once the decay passes through enamel, the dentinal tubules, which have passages to the nerve of the tooth, become exposed, resulting in a toothache. The pain may worsen with exposure to heat, cold, or sweet foods and drinks.