In general, you need three appointments for this orthodontic treatment. The first one is when your dentist will assess your mouth condition and take necessary records. Your second is when you will receive your first set of aligners. Depending on your treatment plan, you may receive them all at once or in batches. The last appointment is to check that the treatment is going as planned.  Your dentist may also give you the retainers during this time. Sometimes, you need more than three appointments if your case is more complicated or you experience some problems along the way, such as severe discomfort.