Methods for designing attachment placement appliances

A method of planning a dental treatment, the method comprising:

• determining a plurality of stages for incremental repositioning of a patient's teeth, wherein the plurality of stages comprises an initial stage, an intermediate stage, and a final stage;
• determining, for at least one of the initial stage, the intermediate stage, or the final stage, a shape of a corresponding dental appliance body,
• wherein the dental appliance body comprises a support formed in a tooth-receiving cavity, one or more coupling structures formed proximate to the support, and an aligner attachment formed proximate to the one or more coupling structures,
• wherein the dental appliance body is configured to align the aligner attachment to a predetermined location on a tooth,
• wherein the aligner attachment is shaped to engage with an attachment well of a shell aligner and exert one or more forces on the tooth when the aligner attachment is coupled to the attachment well, and
• wherein the one or more coupling structures are configured to release the aligner attachment with removal of the dental appliance body from the tooth;
• and
• directly fabricating the dental appliance body.