Final answer:
If a patient doesn't take pre-medication before a dental appointment, the assistant should inform the doctor and seek their guidance on the next steps.
Step-by-step explanation:
If a patient indicates they are required to take pre-medication prior to dental treatment and they didn't do so for the current appointment, the next step the assistant should take is to inform the doctor about the situation. The doctor will then assess the patient's medical history, the type of dental treatment needed, and any potential risks involved. Based on this assessment, the doctor may decide to reschedule the appointment and instruct the patient to take the pre-medication as prescribed before the next visit.