Systems and methods for monitoring a patient's teeth during orthodontic treatment, which may include the use of a series of appliances according to a corresponding series of treatment stages. The system may include a device in communication with one or more sensors of a first appliance implementing a particular treatment stage. The device may be configured to receive monitoring data corresponding to sensor data captured at the one or more sensors, where the sensor data is associated with at least one parameter related to a change in position or movement of the teeth. The device may further be configured to predict tooth positions or movements based on the sensor data, and compare the predicted tooth positions or movements to expected tooth positions or movements. The device may additionally be configured to determine that the first appliance should be replaced with a second appliance based on the comparison.