Final answer:
The maximum recommended dosage of mepivacaine plain for a single appointment is 400 mg, which should be adjusted based on the patient's health and weight.
Step-by-step explanation:
The maximum recommended local anesthetic dosage for mepivacaine plain, without vasoconstrictor, for a healthy adult patient is 400 mg per appointment. This corresponds to approximately 5.5 mg/kg in an adult weighing 70 kg. Local anesthetics should be used with caution, considering the patient's overall health and weight, and the duration of the procedure.