A computer implemented method for creating a dental appliance having a cavity for an unerupted or erupting tooth, comprising: identifying, via a computing device, whether a patient's arch contains an unerupted or erupting tooth; obtaining virtual maximum dimensional tooth data by selecting and comparing a number of data sets of tooth anatomies from examples of virtual tooth geometries, wherein said comparison includes an overlaying step, for at least one of three dimensions of at least one unerupted or erupting tooth based on one or more tooth eruption prediction factors, wherein said overlaying step overlays the data sets and takes the data points that are furthest from a reference point to create a tooth shape that is the maximum dimensions of the combined data sets; determining a first projected dimension for the unerupted or erupting tooth based on the dimensional tooth data; determining a scaling factor for the first projected dimension of a cavity of a dental appliance positioned to accommodate the unerupted or erupting tooth as the tooth erupts; and creating the dental appliance configured to reposition at least one tooth of the patient, the dental appliance including the cavity sized according to the determined scaled first projected dimension for the unerupted or erupting tooth, wherein the dental appliance is further adapted to accommodate different gingiva shapes; wherein an outermost surface of said overlaid virtual tooth geometries creates a bubble-like form that represents the maximum extent to which a tooth should extend outward from a reference point in three dimensions, wherein said accommodation of the unerupted or erupting tooth provides for said cavity to, with said dental appliance in position in the mouth, avoid contact with any surface of the unerupted or erupting tooth. identifying, via a computing device, whether a patient's arch contains an unerupted or erupting tooth; obtaining virtual maximum dimensional tooth data by selecting and comparing a number of data sets of tooth anatomies from examples of virtual tooth geometries, wherein said comparison includes an overlaying step, for at least one of three dimensions of at least one unerupted or erupting tooth based on one or more tooth eruption prediction factors, wherein said overlaying step overlays the data sets and takes the data points that are furthest from a reference point to create a tooth shape that is the maximum dimensions of the combined data sets; determining a first projected dimension for the unerupted or erupting tooth based on the dimensional tooth data; determining a scaling factor for the first projected dimension of a cavity of a dental appliance positioned to accommodate the unerupted or erupting tooth as the tooth erupts; and creating the dental appliance configured to reposition at least one tooth of the patient, the dental appliance including the cavity sized according to the determined scaled first projected dimension for the unerupted or erupting tooth, wherein the dental appliance is further adapted to accommodate different gingiva shapes; wherein an outermost surface of said overlaid virtual tooth geometries creates a bubble-like form that represents the maximum extent to which a tooth should extend outward from a reference point in three dimensions, wherein said accommodation of the unerupted or erupting tooth provides for said cavity to, with said dental appliance in position in the mouth, avoid contact with any surface of the unerupted or erupting tooth.