A method usable in creating a subsequent dental appliance, including the step of: digitally removing an appliance from a current digital dental model that includes a representation of a set of physical teeth for a patient, the method comprising: receiving the current digital dental model that includes the representation of the set of physical teeth for the patient with the appliance attached to the representation of the set of physical teeth; creating, based on the received current digital dental model, a new digital dental model that includes the representation of the set of physical teeth without the appliance attached to the representation of the set of physical teeth by: automatically, without human intervention, removing the appliance from the current digital dental model; estimating contours of hidden areas under the applicance; creating tooth contours in the current digital dental model in areas corresponding to the hidden areas based on the estimated contours to create the new digital dental model that includes the representation of the set of physical teeth without the appliance attached to the representation of the set of physical teeth; and preparing to manufacture a subsequent dental appliance for the patient using the created new digital dental model, wherein the new digital dental model is created automatically, without human intervention, by positioning and orienting the digital models of the teeth from the earlier time point without the appliance present according to the representation of the set of physical teeth in the current digital dental model. receiving the current digital dental model that includes the representation of the set of physical teeth for the patient with the appliance attached to the representation of the set of physical teeth; creating, based on the received current digital dental model, a new digital dental model that includes the representation of the set of physical teeth without the appliance attached to the representation of the set of physical teeth by: automatically, without human intervention, removing the appliance from the current digital dental model; estimating contours of hidden areas under the applicance; creating tooth contours in the current digital dental model in areas corresponding to the hidden areas based on the estimated contours to create the new digital dental model that includes the representation of the set of physical teeth without the appliance attached to the representation of the set of physical teeth; and preparing to manufacture a subsequent dental appliance for the patient using the created new digital dental model, wherein the new digital dental model is created automatically, without human intervention, by positioning and orienting the digital models of the teeth from the earlier time point without the appliance present according to the representation of the set of physical teeth in the current digital dental model. automatically, without human intervention, removing the appliance from the current digital dental model; estimating contours of hidden areas under the applicance; creating tooth contours in the current digital dental model in areas corresponding to the hidden areas based on the estimated contours to create the new digital dental model that includes the representation of the set of physical teeth without the appliance attached to the representation of the set of physical teeth; and preparing to manufacture a subsequent dental appliance for the patient using the created new digital dental model, wherein the new digital dental model is created automatically, without human intervention, by positioning and orienting the digital models of the teeth from the earlier time point without the appliance present according to the representation of the set of physical teeth in the current digital dental model.